AMERICAN WOODCOCK FALL MIGRATION ECOLOGY IN THE … · The American woodcock, Scolopax minor, is a...

FALL MIGRATION ECOLOGY OF AMERICAN WOODCOCK IN THE CENTRAL REGION OF THE UNITED STATES

FALL MIGRATION ECOLOGY OF AMERICAN WOODCOCK IN THE CENTRAL REGION OF THE UNITED STATES

A thesis submitted in partial fulfillment of the requirements for the degree of

Master of Science

By

NICHOLAS ANTHONY MYATT, B.S. Northland College, 2002

August 2004 University of Arkansas

This thesis is approved for Recommendation to the Graduate Council Thesis Director: ______________________ David G. Krementz Thesis Committee: ______________________ W. Fredrick Limp ______________________ Kimberly G. Smith

THESIS DUPLICATION RELEASE

I hereby authorize the University of Arkansas Libraries to duplicate this thesis when needed for research and/or scholarship.

Agreed___________________________

Refused__________________________

ACKNOWLEDGMENTS

I would like to thank everyone who made my research possible. Dr. David

Krementz, my major advisor, provided advice and support throughout my project, as

well as provided me with an excellent start to a career in wildlife management and

ecology. Dr. Fred Limp and Dr. Kimberly Smith provided valuable help while

serving on my thesis committee. This project was made possible through funding

from the U.S. Fish and Wildlife Service – Region IV and the Biological Resources

Division of the U.S. Geological Survey.

I especially thank Dr. David Andersen, Dr. Scott Lutz, Dr. John Bruggink,

Kevin Doherty, Jed Meunier, Eileen Oppelt and their field crews who captured and

radio-marked woodcock, and provided information on departure dates.

Housing was provided by Swan Lake National Wildlife Refuge (NWR), Two

Rivers NWR, Marais de Cygnes NWR, Mingo NWR, Lower Hatchie NWR, and St.

Catherine Creek NWR. I would also like to thank my pilot Jimmy Goad for his

incredible abilities to withstand endless hours of aerial radio telemetry and for his

flexibility to my constantly changing schedule.

This project would not have been as enjoyable without the help and support

from my fellow graduate students at the Arkansas Cooperative Fish and Wildlife

Research Unit. I would also like to thank Alicia Korpach who conducted a pilot

season before I began at the Co-op Unit. I would not have been able to complete the

GIS portions of this project without the technical support of John Wilson. Lastly, I

would like to thank my fiancé Jill Babski who has always provided an endless supply

of support and put up with my constant absence during many field seasons.

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TABLE OF CONTENTS

Page

CHAPTER 1: Introduction--------------------------------------------------------------------- 1

Literature Cited-------------------------------------------------------------------------- 9

Figures------------------------------------------------------------------------------------ 14

CHAPTER 2: Fall migration of American woodcock using Central --------------------- 16 Region band recovery and wing receipt data

Abstract----------------------------------------------------------------------------------- 17

Introduction ------------------------------------------------------------------------------ 17

Methods ---------------------------------------------------------------------------------- 18

Migration Progression -------------------------------------------------------------- 19

Migration Direction and Destination --------------------------------------------- 19

Results ------------------------------------------------------------------------------------ 20

Migration Progression -------------------------------------------------------------- 20

Migration Direction and Destination --------------------------------------------- 21

Discussion---------------------------------------------------------------------------- 21

Management Implications---------------------------------------------------------- 24

Literature Cited-------------------------------------------------------------------------- 25

Figures------------------------------------------------------------------------------------ 27

CHAPTER 3: Fall migration rates, routes, and habitat use of American --------------- 67 woodcock in the Central Region

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vi

Abstract ------------------------------------------------------------------------------------ 68

Introduction ------------------------------------------------------------------------------- 68

Study Area--------------------------------------------------------------------------------- 72

Methods------------------------------------------------------------------------------------ 73

Capture --------------------------------------------------------------------------------- 73

Telemetry ------------------------------------------------------------------------------ 74

Habitat---------------------------------------------------------------------------------- 76

Results ------------------------------------------------------------------------------------- 78

Sample Size---------------------------------------------------------------------------- 78

Telemetry ------------------------------------------------------------------------------ 79

Migration Distance ------------------------------------------------------------------- 80

Stopover Duration -------------------------------------------------------------------- 80

Migration Habitat --------------------------------------------------------------------- 80

Winter Habitat------------------------------------------------------------------------- 82

Fall Migration Routes ---------------------------------------------------------------- 82

Potential Habitat Map ---------------------------------------------------------------- 83

Discussion --------------------------------------------------------------------------------- 83

Management Implications --------------------------------------------------------------- 90

Literature Cited --------------------------------------------------------------------------- 92

Figures ------------------------------------------------------------------------------------- 97

Tables -------------------------------------------------------------------------------------- 115

CHAPTER 1

INTRODUCTION

The American woodcock, Scolopax minor, is a popular, migratory game bird

throughout the eastern half of the United States, annually providing an estimated 3.4

million days of recreational hunting (U.S. Department of Interior 1988). Woodcock

population management is separated into two management units, the Eastern and

Central Regions (Coon et al. 1977) (Fig. 1). The U.S. Fish and Wildlife Service

monitors woodcock populations in each region using a series of singing ground

surveys that exploit the courtship display of male woodcock on breeding grounds.

Each randomly selected survey route is sampled annually during peak seasonal

courtship activities. Population indices are calculated using average number of

singing woodcock per route, weighted for land area (Tautin et al. 1983). Since annual

surveys began in 1968, population indices have annually declined 2.3% in the Eastern

Region and 1.8% in the Central Region (Kelley 2003). Breeding population indices

were the lowest in 1997 in the Central Region and 1995 in the Eastern Region (Kelley

2003).

Widespread habitat alteration and loss caused by human development and

forest succession are thought to be the primary causes of woodcock population

declines. In the northeastern United States, hardwood seedling-sapling stand area has

decreased by 26% over the last 20 years (Desseckar and Pursglove 2000).

Furthermore, the total area of aspen (Populus spp.) forest in Minnesota, Michigan and

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Wisconsin has decreased by 21% since the mid-1960s (Desseckar and Pursglove

2000).

In the U. S., the largest concentration of bottomland hardwood forest, primary

woodcock wintering habitat, occurs in the Lower Mississippi Alluvial Valley (MAV).

Until the 1930s, the MAV has remained largely untouched and undeveloped due to

seasonal flooding. Extensive reduction and degradation has taken place since that

time, largely due to water control, which was followed by land clearing (Newling

1990). From the 1950s to 1970s, bottomland hardwood forests were lost at a rate

exceeding 120,000 ha per year (MacDonald et al. 1979). Of the original 10 million

hectares of bottomland hardwood forest in the MAV, 7.2 million hectares have been

cleared for agriculture (King and Keeland 1999).

Although hunting is not considered to be a major cause of woodcock

population declines, the U.S. Fish and Wildlife Service restricted hunting in the

Eastern Region in 1985, with additional restrictions in the Eastern and Central

Regions in 1998 (Woehr 1999). These restrictions included a reduction from a 65-

day hunting season and a 5-bird limit to 45 days in the Central Region and 30 days in

the Eastern Region, each with a 3-bird limit (Kelley 2003). Woodcock population

indices continue to decline despite reductions in season length and daily bag limit.

Little research has been conducted on the fall migration ecology of this

species. Although the timing of departure from the breeding grounds and arrival on

the wintering grounds has been documented, little is known about what happens

during the migration period. To effectively manage woodcock, managers need to

consider fall migration habitat use, timing, and routes.

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The woodcock range is restricted to the eastern half of North America south

of the Taiga (Keppie and Whitting 1994). In the Central Region, woodcock primarily

breed in the states and provinces surrounding the Great Lakes, but woodcock have

been documented breeding in low densities as far south as Louisiana. Woodcock

primarily over-winter in the Gulf Coastal states, with the highest densities thought to

occur in southern Louisiana (Glasgow 1958). The northern extent of the wintering

range varies due to winter severity, with birds spreading throughout Louisiana during

mild, wet winters and concentrating in south central Louisiana during cool, dry

winters (Glasgow 1958). Straw et al. (1994) estimated wintering densities using 5

years of Christmas Bird Count (CBC) data collected within a 2-week period around

25 December. They concluded that woodcock winter farther north and west than

previously thought, with low densities of wintering birds reaching to southern

Missouri and the western extent reaching across the eastern half of Texas.

Woodcock habitat use has been studied extensively on the northern breeding

grounds and to a lesser extent on the wintering grounds. Understory structure is more

important than species composition; however, species composition can affect food

supply (e.g., earthworm density) and habitat structure (Straw et al. 1994). Woodcock

use a wide range of structural habitat types on the breeding and wintering grounds,

with very dense or very open habitats used least (Cade 1985). Dense shrub or tree

cover may inhibit flight and sparse cover may not provide protection from avian

predators. Vegetative cover may be more important than prey availability in

determining diurnal habitat use on the wintering grounds (Johnson and Causey 1982,

Boggus and Whiting 1982).

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Diurnal woodcock cover on the breeding grounds primarily consists of early

successional, second growth hardwood forest, especially those containing aspen or

alder (Godfrey 1974, Gregg 1984, Straw et al. 1994) with moist soils. Conifer stands

are seldom used, except during drought conditions (Sepik et al. 1983).

Woodcock use a greater variety of habitats on the wintering grounds than on

the breeding grounds (Keppie and Whiting 1994). Bottomland hardwood forest are

historically considered to provide the best habitat, but pinelands and associated

drainages also offer wintering habitat throughout the southeastern U.S. (Reid and

Goodrum 1953, Glasgow 1958, Pursglove 1975, Kroll and Whiting 1977, Pace and

Wood 1979, Johnson and Causey 1982). Glasgow (1958) found wintering woodcock

in Louisiana typically in bottomland hardwood forest with scattered cane

(Arundinaria gigantean) thickets and blackberry (Rubus spp.). Wintering woodcock

in eastern Texas were found in 2-year-old pine clearcuts, as well as pole and mature

sized mixed pine/hardwood stands (Kroll and Whiting 1977).

Pine forests used vary from clear-cuts of loblolly (Pinus taeda) and shortleaf

(Pinus echinata) pine (Kroll and Whiting 1977, Boggus and Whiting 1982) to mature

stands of longleaf (Pinus palustris) pine (Johnson and Causey 1982). When moisture

is limited, mixed pine-hardwood stands and hardwood drainages provide more

suitable habitat than predominantly pine areas (Boggus and Whiting 1982).

Bourgeois (1977) hypothesized that woodcock were selecting diurnal cover based on

structural characteristics rather than species composition. He found that woodcock

hens primarily used early successional forests characterized by high densities of

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seedling-saplings. Britt (1971) determined that canopy closure (structure) was more

important than overstory species composition.

Earthworms are the primary food of woodcock, comprising 79% and 75% of

their diet on the breeding and wintering grounds, respectively (Sperry 1940). The

distribution and density of earthworms in different soils is highly variable due to

factors such as soil moisture, pH, temperature, texture, type and land use history. On

the breeding grounds, Aporrectodea tuberculata and Dendrobaena octaedra prefer

soil moistures of 15-80%, high pH, and temperatures of 10-18ºC (Reynolds et al.

1977). If soil moisture becomes low, earthworms aestivate in a mucus cocoon or

move deeper into the soil (Edwards and Lofty 1977) below the probing depth of

woodcock. Earthworms are found in a wide variety of soils, ranging from gravelly

sand to clay, but the greatest densities occur in light loam soils (Guild 1948,

Nicholson and Owen 1982, Owen and Galbraith 1989).

Most woodcock leave the breeding grounds between October and December

(Godfrey 1974, Coon et al. 1976, Gregg 1984, Sepik and Derleth 1993, Keppie and

Whitting 1994). In Maine and Wisconsin, woodcock do not begin lipogenisis until

early-October so they were not physiologically ready to migrate until mid-October

(Owen and Krohn 1973, Gregg 1984). Woodcock initiate migration from

Pennsylvania between late-November and early-December (Coon et al. 1976),

October and November in Wisconsin (Gregg 1984), and early November in

Minnesota (Godfrey 1974).

Information on the timing of migration flights in mid-latitude states comes

largely from anecdotes and harvest data. In Missouri, mean woodcock harvest date,

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determined using 1972-1979 wing-receipt data, was 6 November (Murphy 1983).

Peak migration in Kentucky and Tennessee begins after the first week of November

with the largest number of birds present in the second and third week of November

(Russell 1958, Roberts 1978). Woodcock begin arriving in Oklahoma in mid-

October with peak sightings occurring between 11 November and 10 December

(Barclay and Smith 1977). Woodcock occupy the wintering grounds in Louisiana

from November to February (Martin et al. 1969) with maximum numbers arriving in

mid-December (Glasgow 1958, Martin et al. 1969, Keppie and Whitting 1994).

Abundance and distribution of woodcock in Louisiana varies with winter severity

(Williams 1969) and precipitation.

Woodcock migration studies have used band recovery data, flush counts,

anecdotal evidence, and small samples of radio-marked woodcock to determine

migration timing (Glasgow 1958, Krohn et al. 1977, Roberts 1978, Sepik and Derleth

1993). A woodcock, radio-marked by Sepik and Derleth (1993) was shot in New

York on 9 November, two days after it was last located 680 km away in Maine. Coon

et al. (1976) initiated a study in Pennsylvania using radio telemetry to gather data on

migration timing. This is the only published study to date that radio-tracked

woodcock after fall migration began. The majority of their radio-marked woodcock

departed between 2.5 hours after sunset and midnight. All woodcock departures

during the study occurred during an 11-day period preceding a full moon (Coon et al

1976). They tracked two hatch-year females during portions of their migratory

flights. In 1973, one female traveled 56 km on her first night of migration. The

following evening she resumed migration and was followed for 56 km until weather

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conditions became unsuitable for the tracking aircraft. In 1974, a female flew 53 km

on her first night of migration. The following evening she resumed migration and

was followed for nearly 148 km until the signal was lost (Coon et al. 1977). The

direction that both woodcock flew coincided with the direction of a river valley,

which led Coon et al. (1976) to suggest that woodcock might follow land features

during migration.

Commencement and progression of fall migration is influenced by weather

with the heaviest flights coinciding with cold fronts (Sepik and Derleth 1993). Gregg

(1984) found that severe cold snaps forced nearly all woodcock out of northern

Wisconsin by 1 November in some years, but mild weather in other years enabled

birds to remain into early winter. Godfrey (1974) reported that woodcock in

Minnesota departed between the retreat of a low-pressure system and the entrance of

a high-pressure center, when winds were most favorable for southerly flight.

Heaviest flights of woodcock have been reported at Cape May, New Jersey, after cold

nights with northwesterly winds (Sheldon 1967). Woodcock initiated migration in

Pennsylvania when high-pressure cells approached from the north and west or when

low-pressure cells retreated to the north and east (Coon et al. 1976). Krementz et al.

(1994) reported an association between woodcock spring migration departure dates

and both moon phase and the passage of weather fronts.

Glasgow (1958) investigated woodcock fall migration routes by plotting 175

band recoveries. Based on these band recoveries, he determined two possible fall

migration routes in the central U.S. (Fig. 2). He described birds migrating along a

western route originating in Minnesota, Wisconsin, Upper Peninsula of Michigan,

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and western Ontario. These birds funneled into the Mississippi River Valley, which

they followed south to central Missouri. The woodcock then spread out across

southern Missouri and Arkansas before reaching Louisiana and east Texas. The

second route described is the central route, which is used by woodcock migration

from Lower Peninsula Michigan, Indiana, Ohio, and eastern Ontario. This route

passed through west Kentucky and west Tennessee, and then followed the eastern

edge of the lower Mississippi Alluvial Valley before reaching southern Mississippi

and Louisiana. Sheldon (1967) plotted 225 additional band recoveries and

hypothesized that birds from Minnesota and Wisconsin are migrating south along the

Mississippi River through the MAV (Fig. 2).

Migration stopovers may be crucial refueling sites for migrants traveling from

the breeding to the wintering grounds. Making a series of short flights is

energetically cheaper than one long flight (Piersma 1987). When there is an

abundance of suitable stopover locations, birds divide their migration into many short

flights, or "hops" (Alerstam and Lindstrom 1990). Hops are frequent, short flights

with many brief refueling periods (Piersma 1987). Habitat availability determines the

flight strategy used by birds. As the distance between suitable stopover sites

increases, migratory flights shift from "hops" to "jumps", where jumps are longer

flight with few but longer stopovers.

Stopover duration is the length of time an individual bird remains at a

stopover site during fall migration. Little information is known about the stopover

duration of woodcock. Other than the observations of two stopover durations by Coon

et al. (1976), there is only anecdotal evidence provided by woodcock hunters.

8

Hunters report that birds can be abundant in coverts one day and gone the next.

These reports have led biologist to believe that stopover duration is short and that

woodcock generally resume migration when weather conditions become favorable.

Accurate information on the distribution and amount of woodcock habitat

within the U.S. remains largely unknown (Cushwa et al. 1977, Duncan 2000).

Managers need better information on the distribution and changes in habitat at the

national level. Forest inventory data have been used to identify trends and

distribution of woodcock habitat (Woehr 1999). Using these data, direct comparisons

between years and states are not always possible due to differing data collection and

reporting methodologies. The advancement of Geographic Information System (GIS)

technologies has potential applications in mapping national woodcock habitat

availability (Duncan 2000). Woodcock select habitat based on structure and age

instead of species composition (Burgeois 1977, Straw et al. 1994), but spatial land

cover data are classified by cover type, generally disregarding structure or

successional stage. Although current data are insufficient to map present distribution

of suitable woodcock habitat in the U.S., those areas that provide no woodcock

habitat can be mapped to provide clues into regional habitat availability, as well as

identify large areas of no potential woodcock habitat.

In 2001 I initiated a project to better understand woodcock fall migration in

the Central Region. The objectives of the project were to use radio telemetry, band

return data, and wing receipt data to: 1) determine the timing and progression of fall

migration 2) document fall migration routes in the Central Region 3) determine

stopover duration of woodcock during fall migration and 4) investigate woodcock

9

habitat use during fall migration. As part of this project, I mapped the distribution of

potential woodcock habitat and identified priority areas for potential future woodcock

management in the Central Region.

LITERATURE CITED

Alerstam, T., and A. Lindstrom. 1990. Optimal bird migration: The relative importance of time, energy, and safety. Pages 331 - 351 in E. Gwinner, editor. Bird migration: physiology and ecophysiology. Springer-Verlag, Berlin, Germany.

Barclay, J. S., and R. W. Smith. 1977. The status and distribution of woodcock in

Oklahoma. Proceedings of the Woodcock Symposium 6:39-50. Boggus, T. G., and R. M. Whiting, Jr. 1982. Effects of habitat variables on foraging

of American woodcock wintering in East Texas. U.S. Fish and Wildlife Service Wildlife Research Report 14:148-153

Bourgeois, A. 1977. Quantitative analysis of American woodcock nest and brood habitat. Proceedings of the Woodcock Symposium 6:108-118. Britt, T. L. 1971. Studies of woodcock on the Louisiana wintering ground. Thesis,

Louisiana State University, Baton Rouge, Louisiana, USA. Cade, B. S. 1985. Habitat suitability index models: American woodcock (wintering).

Biological Report 82. U. S. Fish and Wildlife Service, Washington, D.C., USA.

Coon, R. A., P. D. Caldwell, and G. L. Storm. 1976. Some characteristics of fall migration of female woodcock. Journal of Wildlife Management 40:91-95. _____. 1977. Nesting, habitat, fall migration, and harvest characteristics of the

American woodcock in Pennsylvania. Thesis, Pennsylvania State University, College Junction, Pennsylvania, USA.

_____, T. J. Dwyer, and J. W. Artmann. 1977. Identification of potential harvest

units in the United States for the American woodcock. Proceedings of the Woodcock Symposium 6:147-153. Cushwa, C. T., J. E. Barnard, and R. B. Barnes. 1977. Trends in woodcock habitat in

the United States. Proceedings of the Woodcock Symposium 6:31-37.

10

Dessecker, D. R., and S. R. Pursglove, Jr. 2000. Current population status and likely future trends for American woodcock. Pages 3-8 in D. G. McAuley, J. G. Bruggink, and G. F. Sepik, editors. Proceedings of the Ninth American Woodcock Symposium. U.S. Geological Survey, Biological Resources Division Information and Technology Report USGS/BRD/ITR-2000-0009, Patuxent Wildlife Research Center, Laurel, Maryland, USA.

Duncan, P. S. 2000. American woodcock management, past, present, and future.

Pages 1-2 in D. G. McAuley, J. G. Bruggink, and G. F. Sepik, editors. Proceedings of the Ninth American Woodcock Symposium. U.S. Geological Survey, Biological Resources Division Information and Technology Report USGS/BRD/ITR-2000-0009, Patuxent Wildlife Research Center, Laurel, Maryland, USA.

Edwards, C. A., and J. R. Lofty. 1977. Biology of earthworms. John Wiley and Sons, New York, New York, USA.

Glasgow, L. L. 1958. Contributions to the knowledge of the ecology of the

American Woodcock, Philohela minor (Gmelin), on the wintering range in Louisiana. Dissertation, Texas A & M College, College Station, Texas, USA.

Godfrey, G. A. 1974. Behavior and ecology of American woodcock on the breeding

range in Minnesota. Dissertation, University of Minnesota, Minneapolis, Minnesota, USA.

Guild, W. F. M. L. 1948. The effects of soil type on the structure of earthworm populations. Annals of Applied Biology 35:181-192. Gregg, L. 1984. Population ecology of woodcock in Wisconsin. Wisconsin Department of Natural Resources. Technical Bulletin 144. Johnson, R. C., and M. K. Causey. 1982. Use of longleaf pine stands by woodcock

in southern Alabama following prescribed burning. U.S. Fish and Wildlife Service, Wildlife Research Report 14:120-125.

Kelley, J. R., Jr. 2003. American woodcock population status, 2003. U.S. Fish and

Wildlife Service, Laurel, Maryland, USA. Keppie, D. M. and R. M. Whiting, Jr. 1994. American woodcock (Scolopax minor).

The birds of North America, no. 100. The American Ornithologists’ Union, Washington, D.C., USA, and The Academy of Natural Sciences, Philadelphia, Pennsylvania, USA.

King, S. L., and B. D. Keeland. 1999. Evaluation of reforestation in the Mississippi

River Alluvial Valley. Restoration Ecology 7:348-359.

11

Krementz, D. G., J. T. Seginak, and G. W. Pendleton. 1994. Winter movements and spring migration of American woodcock along the Atlantic Coast. Wilson Bulletin 106:482-493.

Krohn, W. B., J. C. Rieffenberger, and F. Ferrigno. 1977. Fall migration of

woodcock at Cape May, New Jersey. Journal of Wildlife Management 41:104-111.

Kroll, J. C., and R. M. Whitting. 1977. Discriminate function analysis of woodcock

winter habitat in east Texas. Proceedings of the Woodcock Symposium 6:63-71.

MacDonald, P. O., W. E. Frayer, and J. K. Clauser. 1979. Documentation,

chronology, and future projections of bottomland hardwood habitat loss in the lower Mississippi Alluvial Plain. Volume 1, basic report. HRB-Singer, Inc., State College, Pennsylvania, USA.

Martin, F. W., S. O. Williams, J. D. Newsom, and L. L. Glasgow. 1969. Analysis of

records of Louisiana banded woodcock. Proceedings of the Southeastern Association of Game and Fish Commissioners 23:85-96.

Murphy, D. W. 1983. Ecology of American woodcock in central Missouri. Thesis,

University of Missouri, Columbia, Missouri, USA. Newling, C. J. 1990. Restoration of bottomland hardwood forests in the Lower

Mississippi Valley. Restoration and Management Notes 8:23-28. Nicholson, C. P., and R. B. Owen, Jr. 1982. Earthworm abundance in selected forest habitats in Maine. Megadrilogiea 41:78-80. Owen, R. B., and W. B. Krohn. 1973. Molt patterns and weight changes of the

American woodcock. Wilson Bulletin 85:31-41. _____, and W. J. Galbraith. 1989. Earthworm biomass in relation to forest types,

soil and land use: Implications for woodcock management. Wildlife Society Bulletin 17:130-136.

Pace, R. M., III, and G. W. Wood. 1979. Observations of woodcock wintering in

coastal South Carolina. Proceedings of the Southeastern Association of Game and Fish Commissions 33:72-80.

Piersma, T. 1987. Hop, skip, or jump? Constraints on migration of arctic waders by

feeding, fattening, and flight speed. Limosa 60:185-194. Pursglove, S. R. 1975. Observations on wintering woodcock in northeast Georgia.

12

Proceedings of the Southeastern Association of Game and Fish Commissions 29:630-639.

Reid, V., and P. Goodrum. 1953. Wintering woodcock populations in west central

Louisiana, 1952-53. U.S. Fish and Wildlife Service, Special Scientific Report Wildlife 24.

Reynolds, J. W., W. B. Krohn, and G. A. Jordan. 1977. Earthworm populations as

related to woodcock habitat usage in central Maine. Proceedings of the Woodcock Symposium 6:135-146.

Roberts, T. H. 1978. Migration, distribution, and breeding of American woodcock. Tennessee Wildlife Resources Agency, Technical Report 79.

Russell, D. M. 1958. Woodcock and Wilson’s snipe studies in Kentucky. Kentucky

Department of Fish and Wildlife Resources. Project Report W-31-R. Sepik, G. F., and E. L. Derleth. 1993. Premigratory dispersal and fall migration of American woodcock in Maine. Biological Report 16:36-40. ____, _____, and T. J. Dwyer. 1983. The effect of drought on a local woodcock

population. Transactions of Northeast Fish and Wildlife Conference 40:1-8. Sheldon, W. G. 1967. The book of the American woodcock. University of Massachusetts Press, Amherst, Massachusetts, USA. Sperry, C. C. 1940. Food habits of a group of shorebirds: Woodcock, snipe, knot,

and dowitcher. U.S. Biological Survey, Wildlife Resources Bulletin 1. Straw, J. A., D. G. Krementz, M. W. Olinde, and G. F. Sepik. 1994. American

woodcock. Pages 97-114 in T.C. Tacha and C.E. Braun, editors. Migratory shore and upland game bird management in North America. International Association of Fish and Wildlife Agencies, Washington, D.C., USA.

Tautin, J., P. H. Geissler, R. E. Munro, and R. S. Pospahala. 1983. Monitoring the

population status of American woodcock. Transactions of the North American Wildlife Conference 48:376-388.

U.S. Department of Interior. 1988. 1985 National survey of fishing, hunting and

wildlife associated recreation. U.S. Government Printing Office, Washington, D.C., USA.

Williams, S. O., III. 1969. Population dynamics of woodcock wintering in

Louisiana. Thesis, Louisiana State University, Baton Rouge, Louisiana, USA. Woehr, J. R. 1999. Declines in American woodcock populations: Probable cause

13

and management recommendations. The report of the Woodcock Task Force to the Migratory Shore and Upland Game Bird Subcommittee, Migratory Wildlife Committee, International Association of Fish and Wildlife Agencies.

14

Krementz

This reference will need some more information I think.

Figure 1. Woodcock management regions determined by Coon et al. (1977) using band recovery data.

15

Figure 2. Possible American woodcock fall migration route proposed by Glasgow (1958) and Sheldon (1967) using band return data.

16

Chapter 2

FALL MIGRATION OF AMERICAN WOODCOCK USING CENTRAL REGION BAND RECOVERY AND WING RECEIPT DATA¹

_________________ ¹Myatt, N. A., and D. G. Krementz. To be submitted to The Journal of Wildlife Management.

17

Abstract: Band recovery and wing receipt data have potential to provide information

on fall migration ecology of American woodcock in the Central Region, yet these

extensive data sets have not been recently analyzed. I examined all direct recoveries

of woodcock banded in Michigan, Minnesota and Wisconsin, as well as wing receipt

data, to determine the progression of fall migration and the migration direction and

final destination of woodcock migrating from these states. Migration initiation was

not observed until late October and early November, with most migration occurring

during November. Wing receipt data showed a similar trend, with most change in

mean receipt latitude occurring from 1 November – 5 December. During November,

wing receipts were spread through the entire Central Region. Band recovery data

demonstrated that during 1-15 December, birds were spread throughout the southern

U.S. During 15-31 December, 92.3% (n=26) of band recoveries were on the

wintering grounds (south of 33º N latitude). Most banded woodcock from Michigan,

Minnesota, and Wisconsin wintered in Louisiana, but some Michigan banded

woodcock were recovered as far east as Georgia and South Carolina. Hunting

seasons on the breeding grounds start in late-September before migration initiation.

Managers need to consider the effects of harvesting locally produced birds on

woodcock populations.

INTRODUCTION

Little information has been published on the fall migration ecology of

American woodcock in the Central Region (Keppie and Whiting 1994), which

includes the woodcock’s range west of the Appalachian Mountains (Coon et al.

18

1977). The only available information on woodcock fall migration timing and routes

were based on anecdotal evidence, reports of migration initiation in small numbers of

radio-marked woodcock (Coon et al. 1976, Gregg 1984), and analysis of band return

data from the 1950s to the early-1980s (Glasgow 1958, Sheldon 1967, Krohn et al.

1977, Gregg 1984). Since then, many woodcock bands have been recovered and

computer technologies have advanced to aid in mapping and analysis of band

recovery data.

The U.S. Fish and Wildlife Service (USFWS) collects data on annual

woodcock reproductive rates using a parts collection survey. Survey participants

were asked to submit one wing from each woodcock harvested (Kelley 2003).

Murphy (1983) used woodcock wing receipt data to estimate peak fall migration of

woodcock in Missouri. While wing receipt densities are influenced by hunter

densities, hunting season dates, and participation in the program, these data can

provide valuable information on woodcock migration.

I analyzed Central Region woodcock banding and wing receipt data to: 1)

determine the timing and progression of fall migration, and 2) to determine the

direction and final destination of woodcock migrating from Minnesota, Wisconsin,

and Michigan.

METHODS

I obtained woodcock banding data from the Bird Banding Lab for 1929-2001.

Band returns from Central Region banded woodcock with known day, month, year,

and 10-minute block were used in my analysis. The USFWS also provided historic

19

wing receipt data from 1963-2002 (J.R. Kelley, Jr. US FWS, personal

communication). I used ESRI Geographic Information System (GIS) software to

query, analyze, and map band return and wing receipt densities.

Migration Progression

In my analysis of migration progression, I used all direct recoveries of birds

banded in the northern half of the U.S. portion of the Central Region and recovered

between 1 September and 31 December, 1929-2001. I queried these recoveries by 2-

week periods from 1 September-31 December. Banding and recovery locations were

mapped for each period with lines connecting the two locations to facilitate

interpretation. I determined mean band recovery latitude by computing the average

latitude of all band returns during each 2-week period.

In my analysis of migration progression, I used all woodcock wing receipts

from woodcock shot in the Central Region between 1 September and 31 December

1963-2002. I queried the data by 5-day periods from 1 September-31 December.

During each period, wing receipts for each county were tallied and receipt densities

mapped. I determined the mean wing receipt latitude by computing the average

latitude of all wing receipts during a 5-day period. The center point of each county

was used to determine the latitude of each wing receipt.

Migration Direction and Destination

I investigated the final destination of migrating woodcock using all direct

recoveries of woodcock banded in Minnesota, Wisconsin, and Michigan and

recovered in a different state from 1 September-31 December. I mapped these

locations and drew a line from the banding location to the recovery location. I used

20

an ArcView script to measure the distance and angle between banding and recovery

locations. This script created an Azmuthal map projection centered on the individual

banding location and then measured the distance and angle to the recovery location.

The Azmuthal projection was chosen because it most accurately estimated distances

and angular data from its center point (J. Wilson, Center for Advanced Spatial

Technology, personal communication).

I used program ORIANA for Windows (Provalis Research) to estimate mean

migration angle and associated circular statistics of the migration angles (angle

between banding and recovery location) of all band recoveries outside of the banding

state. Using these data, I created roses were to visually display migration angles for

each state.

RESULTS

Migration Progression

Mean woodcock band recovery latitude remained relatively constant

throughout the early fall, until a slight shift south was observed during 16-31 October

(Fig. 1). I observed the largest change in mean latitude between 1-15 November.

After this period, mean latitude gradually decreased during the final two periods (Fig.

1). Looking at the migration progression maps created from banding data (Fig. 2 - 9),

no migration was evident until 1-15 November when woodcock were being

recovered throughout the northern half of the Central Region (Fig. 6). During 16-30

November, woodcock were being recovered throughout the southern half of the

Central Region (Fig. 7).

21

Mean woodcock wing receipt latitude followed a pattern similar to band

recovery data. No substantial change in latitude was observed until 21-25 October

(Fig. 10). Mean latitude steadily decreased throughout November until 1-5 December

when mean latitude leveled off (Fig. 10). Wing receipt density maps (Fig. 11 - 34)

showed that throughout November, woodcock wings were returned throughout the

Central Region. Densities of wing returns in Louisiana gradually increased during

the later half of November and reach high densities by 11-15 December (Fig. 31).

Migration Direction and Destination

The map of Minnesota (Fig. 35) out-of-state direct recoveries (n=7) indicated

that woodcock migrated straight south to the winter grounds in Louisiana. Wisconsin

birds (n=37) were recovered during migration as far east as Kentucky and as far west

as Oklahoma, with the majority of recoveries on the winter grounds in Louisiana (Fig.

36). Michigan recoveries (n=37) were more widely scattered than recoveries from

the other two states (Fig. 37). Michigan banded birds were recovered on the winter

grounds in east Texas, Louisiana, Mississippi, Alabama, and Georgia. Two Michigan

birds were recovered after traveling east of Michigan into Pennsylvania and

Massachusetts (Fig. 37).

Minnesota direct recoveries (n=7) had a mean migration angle of 168º (95%

CI: 188° - 206°) (Fig. 38). This angle was skewed east by two recoveries in

Wisconsin. Wisconsin direct recoveries (n=37) were further west with a mean

migration angle of 182º (95% CI: 179° - 185°) (Fig. 38). Michigan direct recoveries

(n=37) had a migration angle further west than the other two states, with a mean

migration angle of 197º (95% CI: 188° to 206°) (Fig. 38).

22

DISCUSSION

Woodcock were harvested in the Great Lakes States throughout November. This

wide range of harvest dates showed that migration initiation was drawn out over a

period of a few weeks. The dates of peak migration vary among years further adding

to this range. Migration occurred over a relatively short time period, with nearly all

evidence of migration between 1 November and 15 December. The variances in

mean wing receipt and band recovery latitude were greatest during 15-30 November,

at which point migrating woodcock were spread throughout the entire Central Region.

During migration, shorebird species are thought to concentrate along defined

routes and rely on a few historic stopover areas where they can replenish fat reserves

(Myers et al. 1987, Skagen 1997). Band recovery and wing receipt data did not

support the idea of exact migration routes or historic stopover areas for woodcock;

however, the direction of general migration routes was evident. Woodcock banded in

Minnesota and Wisconsin appeared to migrate straight south to the winter grounds.

The majority of Michigan banded woodcock appeared to have migrated south through

eastern Indiana and Illinois, and then south to the wintering grounds through east

Kentucky, east Tennessee, and Mississippi.

Several wing receipts were suspect. These locations were woodcock reported

harvested in the far north in late-December or in the Gulf Coastal states in mid-

September. I realize there are several possible explanations for this, but regardless of

the cause of these locations, they are so few that they did not significantly affect my

results. Another factor that could have possibly affected my results was a difference

23

in hunting pressure. Woodcock are hunted heavily in the Great Lakes states and

Louisiana, so the majority of wing receipts and band recoveries were from those

locations.

Compared to other states, few wing receipts were received from Iowa or

Arkansas. Why these two states had noticeably fewer wing receipts is not clear, but

may include: 1) fewer woodcock being harvested in either state, 2) fewer hunters

participated in the Parts Collection Survey, or 3) woodcock migration stopover

duration was shorter or absent in those states. Maps of all Central Region wing

receipts (Fig. 39) showed a possible trend of densities decreasing from the Great

Lakes states into Iowa and northern Illinois, then increasing in Missouri and southern

Illinois, decreasing again in Arkansas, northern Mississippi, and northern Alabama,

and finally increasing again in Louisiana. This trend provides evidence that

woodcock were possibly migrating over the areas of low abundance and stopping

over in areas of high abundance (i.e. the mid-latitude states). Woodcock were

harvested in all states in the Central Region during fall migration, so I know that birds

were not migrating in one long flight from the breeding to wintering grounds.

Making a series of short flights is always energetically cheaper than one large

flight due to the cost of transporting extra fat (Piersma 1987). Limited availability of

high quality foraging sites is thought to be the reason for shorebirds making long

flights (Piersma 1987). Further research into the availability and quality of woodcock

habitat in the central U.S. might provide information on woodcock migration routes

and flight duration.

24

Most woodcock band recoveries from Minnesota and Wisconsin appeared to

follow the same direction, but there was a large variance in the Michigan recoveries.

Two woodcock banded in Michigan were recovered nearly straight east of their

banding location in Pennsylvania and Massachusetts. Recognize though that such

recoveries could be reporting errors in the Bird Banding Lab files. Woodcock banded

in Minnesota and Wisconsin appeared to overwinter in Louisiana, east Texas, and

west Mississippi. Michigan banded woodcock were recovered on the wintering

grounds throughout the southeastern U.S., however all band recoveries of Michigan

banded woodcock in Alabama, Georgia, and South Carolina were recovered >25

years ago.

There have been a variety of woodcock publications describing their wintering

range. Sheldon (1967) reported that woodcock mainly winter in southeastern

Arkansas, Louisiana, and south-western Mississippi. Straw et al. (1994) analyzed

Christmas Bird Count data and reported that wintering woodcock are common to

abundant in southern Louisiana and east Texas but their wintering range in the central

region extended north to central Missouri. Woodcock winter further north in some

years than others (Williams 1969, Britt 1971, Roberts 1993). Despite these few birds

that overwinter north of traditional areas, I found that most woodcock winter south of

33º N latitude and arrive at their wintering location by 15 December. Of the bands

recovered from 16-31 December, 92.3% were south of 33º N latitude, which

supported Glasgow's (1958) findings that the majority of woodcock are on the

wintering grounds by 15 December. This is further supported by the wing receipt

data, which indicated that harvest leveled off in Louisiana by 15 December.

25

MANAGEMENT IMPLICATIONS Band recovery and wing receipt data both showed little sign of woodcock migration

until 1 November. Woodcock hunting seasons in the Great Lakes states open in late-

September, over a month before migration occurs. Managers need to consider the

effects of harvesting locally produced birds on woodcock populations in their own

states/provinces.

Further investigation is needed to determine the cause of the lack of wing

receipts in Iowa and Arkansas. Outreach efforts might be needed to increase the

amount of public participation in the USFWS Parts Collection Survey in these areas.

Woodcock banding efforts in the Great Lakes states need to be continued to obtain

more information on woodcock fall migration ecology through increased sample

sizes.

LITERATURE CITED Britt, T. L. 1971. Studies of woodcock on the Louisiana wintering ground. Thesis,

Louisiana State University, Baton Rouge, Louisiana, USA. Coon, R. A., P. D. Caldwell, and G. L. Storm. 1976. Some characteristics of fall

migration of female woodcock. Journal of Wildlife Management 40:91-95. _____, T. J. Dwyer, and J. W. Artmann. 1977. Identification of potential harvest

units in the United States for the American woodcock. Proceedings of the Woodcock Symposium 6:147-153. Gregg, L. 1984. Population ecology of woodcock in Wisconsin. Wisconsin Department of Natural Resources. Technical Bulletin 144. Kelley, J.R., Jr. 2003. American woodcock population status, 2003. U.S. Fish and

Wildlife Service, Laurel, Maryland, USA.

26

Keppie, D. M. and R. M. Whiting, Jr. 1994. American woodcock (Scolopax minor). The birds of North America, no. 100. The American Ornithologists’ Union, Washington, D.C., USA, and The Academy of Natural Sciences, Philadelphia, Pennsylvania, USA.

Krohn, W. B., J. C. Rieffenberger, and F. Ferrigno. 1977. Fall migration of


Murphy, D.W. 1983. Ecology of American woodcock in central Missouri. Thesis, University of Missouri, Columbia, Missouri, USA. Meyers, J.P., R. I. G. Morrison, P. Z. Antas, B. A. Harrington, T. E. Lovejoy, M.

Sallaberry, S. E. Senner, and A. Tarak. 1987. Conservation strategy for migratory species. American Science 75:18-26.

Piersma, T. 1987. Hop, skip, or jump? Constraints on migration of arctic waders by feeding, fattening, and flight speed. Limosa 60:185-194. Roberts, T. H. 1993. The ecology and management of wintering woodcocks.

Biological Report 16:87-97 Sheldon, W. G. 1967. The book of the American woodcock. University of Massachusetts Press, Amherst, Massachusetts, USA. Skagen, S. K. 1997. Stopover ecology of transitory populations: The case of

migrant shorebirds. Ecological Studies 125:244-269. Williams, S. O. III. 1969. Population dynamics of woodcock wintering in Louisiana. Thesis, Louisiana State University, Baton Rouge, Louisiana, USA.

27

Band Recoveries

28

30

32

34

36

38

40

42

44

46

48

1 - 15 16 - 30 1 - 15 16 - 31 1 - 15 16 - 30 1 - 15 16 - 31

Latit

ude

September October November December Figure 1. Mean (+/- SD) latitude of all woodcock banded in Minnesota, Wisconsin, and Michigan and directly recovered during 15-day periods between 1 September and 31 December 1929-2001.

28

Figure 2. Woodcock banding and direct recovery locations for individuals banded in Minnesota, Wisconsin, and Michigan and recovered between 1-15 September, 1929-2001. Banding and associated recovery locations are connected with a line.

29

Figure 3. Woodcock banding and direct recovery locations for individuals banded in Minnesota, Wisconsin, and Michigan and recovered between 16-30 September, 1929-2001. Banding and associated recovery locations are connected with a line.

30

Figure 4. Woodcock banding and direct recovery locations for individuals banded in Minnesota, Wisconsin, and Michigan and recovered between 1-15 October, 1929-2001. Banding and associated recovery locations are connected with a line.

31

Figure 5. Woodcock banding and direct recovery locations for individuals banded in Minnesota, Wisconsin, and Michigan and recovered between 16-31 October, 1929-2001. Banding and associated recovery locations are connected with a line.

32

Figure 6. Woodcock banding and direct recovery locations for individuals banded in Minnesota, Wisconsin, and Michigan and recovered between 1-15 November, 1929-2001. Banding and associated recovery locations are connected with a line.

33

Figure 7. Woodcock banding and direct recovery locations for individuals banded in Minnesota, Wisconsin, and Michigan and recovered between 16-30 November, 1929- 2001. Banding and associated recovery locations are connected with a line.

34

Figure 8. Woodcock banding and direct recovery locations for individuals banded in Minnesota, Wisconsin, and Michigan and recovered between 1-15 December, 1929-2001. Banding and associated recovery locations are connected with a line.

35

Figure 9. Woodcock banding and direct recovery locations for individuals banded in Minnesota, Wisconsin, and Michigan and recovered between 16-31 December, 1929-2001. Banding and associated recovery locations are connected with a line.

36

Wing Receipts

28

33

38

43

48

53

1 - 5 11 - 15 21 - 25 1 - 5 11 - 15 21 - 25 1 - 5 11 - 15 21 - 25 1 - 5 11 - 15 21 - 25

Latit

ude

September October November December Figure 10. Mean (+/- SD) latitude for all woodcock wings sent to the U.S. Fish and Wildlife Service parts collection survey from birds shot during 5-day periods between 1 September and 31 December 1963-2003. The center point of each county was used as the harvest latitude for each wing receipt.

37

Figure 11. Density of woodcock wings received by the U.S. Fish and Wildlife Service Parts Collection Survey from woodcock harvested between 1 - 5 September, 1963 - 2002.

38


39


40

Figure 14. Density of woodcock wings received by the U.S. Fish and Wildlife Service Parts Collection Survey from woodcock harvested from 16 - 20 September, 1963 - 2002.

41


42


43

Figure 17. Density of woodcock wings received by the U.S. Fish and Wildlife Service Parts Collection Survey from woodcock harvested between 1 - 5 October, 1963 - 2002.

44


45


46


47


48


49

Figure 23. Density of woodcock wings received by the U.S. Fish and Wildlife Service Parts Collection Survey from woodcock harvested between 1 - 5 November, 1963 - 2002.

50


51


52


53

Figure 27. Density of woodcock wings received by the U.S. Fish and Wildlife Service parts collection survey from woodcock harvested between 21 - 25 November, 1963 - 2002.

54


55

Figure 29. Density of woodcock wings received by the U.S. Fish and Wildlife Service parts collection survey from woodcock harvested between 1 - 5 December, 1963 - 2002.

56

Figure 30. Density of woodcock wings received by the U.S. Fish and Wildlife Service Parts Collection Survey from woodcock harvested between 6 - 10 December, 1963 - 2002.

57


58


59


60


61

Figure 35. Woodcock direct recoveries (n=7) from birds banded in Minnesota and recovered in a different state between 1 September to 31 December, 1929 - 2001. Each banding and associated recovery location is connected with a line.

62

Figure 36. Woodcock direct recoveries (n=37) from individual birds banded in Wisconsin and recovered in a different state from 1 September to 31 December, 1929 - 2001. Banding and associated recovery locations are connected with a line

63

Figure 37. Woodcock direct recoveries (n=37) from individual birds banded in Michigan and recovered in a different state from 1 September to 31 December, 1929 - 2001. Banding and associated recovery locations are connected with a line

64

Minnesota n = 7

Minnesota n = 7

Wisconsin n = 37

Michigan n = 37

Figure 38. Mean migration angle and 95% confidence intervals of woodcock banded in Minnesota, Wisconsin, and Michigan and directly recovered in a different state between 1 September to 31 December, 1929 - 2001.

65

Figure 39. Density of woodcock wings received by the U.S. Fish and Wildlife Service Parts Collection Survey from woodcock harvested from 1 September – 31 December, 1963 - 2002.

66

Figure 40. Woodcock band recovery locations from 1 September to 31 December, 1929-2001.

67

Chapter 3

FALL MIGRATION RATES, ROUTES, AND HABITAT USE OF AMERICAN

WOODCOCK IN THE CENTRAL REGION¹ __________________ ¹Myatt, N. A., and D. G. Krementz. To be submitted to The Journal of Wildlife Management.

68

Abstract: American woodcock (Scolopax minor) ecology has been extensively

studied on the breeding grounds and to a lesser extent on the wintering grounds, but

little research has been conducted on the migration ecology of this declining species.

In Fall 2001 I began a 3-year study to document woodcock fall migration routes,

rates, and habitat use in the Central Region of the U.S. From 2001-2003, 582 radio-

marked woodcock initiated migration from 3 study sites in Minnesota, Wisconsin,

and Michigan. Aerial searches were conducted from fixed-wing aircraft during each

fall migration period in the Central Region. During 224 hours of aerial telemetry, I

located 42 radio-marked woodcock in 6 states. Radio-marked birds were located in

upland habitats more frequently than bottomland habitats (80% vs. 20%,

respectively). Migrating woodcock used a higher proportion of mature forest than

expected. Stopover duration often exceeded 4 days, with some birds stopping longer

than a week. Using locations of radio-marked birds, I speculated woodcock

migration routes in the central U.S. GIS was used to map potential woodcock habitat

in the Central Region. Based on my results, I have identified priority areas for future

woodcock management in the Central Region.

INTRODUCTION

American woodcock ecology has been studied extensively on the northern

breeding grounds and to a lesser extent on the wintering grounds, but little research

has been conducted on the migration ecology of this declining species (Keppie and

Whitting 1994). Although the timing of departure from the breeding grounds and

arrival on the wintering grounds has been documented, little is known about what

69

happens during the migration period between these areas. Knowledge of woodcock

migration has been limited to anecdotal evidence, interpretations of a limited sample

of band returns (Glasgow 1958, Sheldon 1967, Krohn et al. 1977), monitoring the

onset of migration in small samples of radio-marked birds (Godfrey 1974, Coon et al.

1976, Gregg 1984, Sepik and Derleth 1993), and harvest data (Roberts 1978, Murphy

1983). Minimal data have been collected in the Central Region (Fig. 1) on migration

habitat use, stopover duration, or fall migration routes of woodcock.

Woodcock breed primarily in dense early successional habitats in the Great

Lakes states and provinces (Keppie and Whitting 1994). They initiate fall migration

in the Central Region in late-October and early-November (Keppie and Whitting

1994). Their nocturnal migratory flights often coincide with the passage of cold

fronts. Owen (1977) documented the winter distribution of woodcock, with the

northern extent ending in northern Louisiana. Glasgow (1958) reported that most

woodcock have arrived on the wintering grounds by 15 December, but their

distribution in Louisiana depended on winter severity. During mild winters,

woodcock were spread throughout Louisiana, while during cool winters they were

absent from the northern half of the state and concentrated in the Atchafalaya and

Mississippi River basins (Glasgow 1958). Straw et al. (1994) analyzed Christmas

Bird Count data and reported that woodcock winter in low densities as far north as

Missouri.

Glasgow (1958) used a sample (n=175) of woodcock band returns to predict

fall migration routes across the woodcock’s range (Fig. 2). Glasgow hypothesized

that woodcock migrating from Minnesota and Wisconsin might follow the

70

Mississippi River south to Missouri where they then travel through central Missouri

and Arkansas on their way to south central Louisiana. Sheldon (1967) used ten

additional years of band return data (n=400) and hypothesized that woodcock

migrating from Minnesota and Wisconsin might follow the Mississippi River south

through the lower Mississippi Alluvial Valley (MAV) to the winter grounds (Figure

2). During the 1950s-1970s, the MAV lost 120,000 hectares per year of bottomland

hardwood forest (MacDonald et al. 1979). Woodcock may no longer use the MAV

during migration due to a lack of suitable migration habitat.

Changes in habitat availability might have caused a change in migration flight

distance and stopover duration, but little is known about these two components of

woodcock migration. A woodcock, radio-marked by Sepik and Derleth (1993) was

shot in New York on 9 November, two days after it was last located 680 km away in

Maine. Coon et al. (1976) documented the distance and stopover duration of 2 fall

migration flights. Two radio-marked woodcock were tracked up to 201 km SSW of

the study area on their first two nights of migration. Both birds traveled 53-56 km on

their first night’s flight. On the second evening of migration, one resumed migration

at 1845 hr and the other departed at 1910 hr. Other than Coon et al. (1976), there is

no other data on the length of each leg of woodcock fall migration, the duration of

stopovers, and the time at which woodcock resume migration during migration

stopovers.

Migration stopover locations are crucial links between breeding and wintering

grounds where avian migrants rest and/or refuel for the next leg of migration (Farmer

and Parent 1997). Many species of shorebirds use traditional stopover locations

71

where a significant portion of the population might stop in a given year (Farmer and

Parent 1997). Stopover duration is the length of time that a migrating bird remains

at a stopover location during fall migration. Stopover duration may be directly

related to the availability of high quality foraging sites (Piersma 1987). Making a

series of short flights is always energetically cheaper than covering the same distance

in one long flight (Piersma 1987). Short stopover durations would provide evidence

that woodcock are migrating in a series of short "hops." Longer stopover durations

would suggest that birds are refueling after migrating in several "jumps," where

jumps are long flights followed by long stopovers. The availability and distribution

of woodcock habitat in part of the Central Region could affect stopover duration.

The extent and distribution of woodcock habitat in the U.S. remains largely

unknown. Advancements in Geographic Information System (GIS) technologies

have potential applications in mapping national woodcock habitat distribution

(Duncan 2000). Currently, nation-wide, spatial data are not sufficient to map

woodcock habitat availability. Suitable woodcock habitat is determined by

vegetation physiognomy rather than species composition (Bourgeois 1977, Cade

1985, Straw et al. 1994), which is the primary classification method of current spatial

data.

In fall 2001, I began a 3-year study of woodcock fall migration ecology in the

Central Region. My project took advantage of a concurrent study on the effects of

hunting mortality on woodcock populations in the Great Lakes region. That study

radio-marked up to 360 woodcock on the breeding grounds each fall and monitored

their location daily until they began migration. Once those birds migrated, I relocated

72

them throughout the Central Region. The objectives of my research were to: 1)

document woodcock fall migration routes in the Central Region, 2) determine the

stopover duration of woodcock during fall migration, and 3) document woodcock

habitat use during fall migration.

STUDY AREA

In North America, the range of woodcock has been divided into 2

management units: Eastern and Central regions (Coon et al. 1977) (Fig. 1). My study

focused on the Central Region, which includes the woodcock’s range west of the

Appalachian Mountains. Woodcock were radio-marked at 3 northern study sites (Fig.

3): 1) Mille Lacs and Four Brooks Wildlife Management Area in east-central

Minnesota (45.93º N, 93.55º W), 2) Lincoln County Forest and Tomahawk

Timberlands in north-central Wisconsin (45.34º N, 89.94º W), and 3) Copper Country

State Forest on the west-central border of Upper Peninsula Michigan (46.15º N,

87.83º W). My aerial search efforts for radio-marked birds were focused in Arkansas,

Illinois, Iowa, Kentucky, Louisiana, Mississippi, Missouri, Oklahoma, Tennessee,

and Texas.

Based on the Palmer Drought Index, fall of 2001 was abnormally dry in

central Minnesota and northeast Arkansas during late-October and early-November

(N.O.A.A. 2004). Otherwise, there were no other drought conditions that year in the

Central Region. In fall 2002, abnormally dry and moderate drought conditions were

present during late-October and early-November in western Missouri and northwest

Arkansas. Later that fall, drought conditions spread throughout Missouri, southern

73

Iowa, northern Illinois, and northern Indiana. There were no abnormally dry

conditions observed in fall 2002 on the wintering or breeding grounds. In fall 2003,

Minnesota, Wisconsin, Michigan, Iowa, and northern Illinois experienced abnormally

dry to moderate drought conditions. During late-October and early-November

northern Louisiana and southern Arkansas also experienced abnormally dry

conditions. During late-November and December, there were abnormally dry

conditions in Oklahoma, northeast Texas, and southeastern Louisiana.

METHODS

Capture

In 2001, woodcock were captured only at the Minnesota study site, while in

August 2002 and 2003, woodcock were captured at each of the 3 northern study sites.

Capture efforts ended 1 October each year to reduce the probability of marking non-

resident woodcock. Woodcock were mist-netted during crepuscular flights between

diurnal habitat and nocturnal feeding fields. Capture by spotlighting from all terrain

vehicles, trucks, and on foot was also used when conditions permitted (Reiffenberger

and Kletzly 1967, McAuley et al. 1993).

After capture, birds were aged and sexed using wing plumage characteristic

(Martin 1964). Birds were outfitted with 4.4-g radio transmitters using all-weather

livestock tag cement and a belly-loop wire harness (McAuley et al. 1993). In 2001

and 2002, active radios had a pulse rate of 55 pulses per minute (ppm) and were

powered by a 1.5-volt silver-oxide battery. Based on the pilot’s observations, the

74

ground to air range of the radios was variable with a mean distance of about 8 km and

a maximum distance of 20 km.

Each radio transmitter had a frequency unique to the capture state, but there

were some frequency overlaps among the 3 states. I considered a bird to be uniquely

identifiable if the frequency of the radio transmitter was >0.007 MHz apart from all

other birds. In 2003, the problem of overlapping frequencies was corrected by setting

half of the radios at 55 ppm and the other half at 70 ppm. Using pulse rate and

frequency, all radio-marked woodcock should have been uniquely identifiable in

2003.

Telemetry

Each day northern field crews confirmed the presence of all radio-marked

birds until they were censored. Once several birds were missing from the study area,

aerial searches from fixed-wing aircraft were performed at 3- to 7-day intervals to

relocate missing birds. After two telemetry flights, if birds were not found within

approximately 24 km of the study area, they were classified as having possibly

migrated. The assumption that a bird had migrated when it could not be located was

problematic due to the possibility of radio failure, temporary emigration, or

unreported harvest, so migration dates and numbers of marked birds may be over

estimated. I communicated weekly with northern field crews to determine which

birds were missing from the study areas and the probable dates when migration

began.

After 50% of the radio-marked woodcock from the northern study areas were

censored, I began diurnal searches for the birds from fixed-wing aircraft. The

75

primary plane that I used was outfitted with two 2-element, directional antennas

(Gilmer et al. 1981). To a lesser extent, I used a different plane outfitted with 2 omni-

directional aircraft antennas (McAuley et al. 1993). I searched at an average airspeed

of 200 km/hr and an altitude of 1000-3000 m. Transmitter frequencies were

programmed into a receiver and scanned on 2-sec intervals for the duration of the

flight.

Before each field season, I contacted wildlife researchers in my study area to

determine the existence of other radio telemetry projects within my frequency range.

When flying over known telemetry projects, the pilot had a list of the frequencies and

locations of radio-marked animals unrelated to my project.

Each season, I flew the first flights in the northern portion of my study area

and then moved flights south as migration progressed. Areas searched and times of

search were based on current literature, historic band return data, wing receipt data,

and relief maps of the Central Region. In the first half of 2002 and in 2001, I flew

along major rivers, bluff edges of the Mississippi River, and randomly over areas of

possible habitat. In 2003 and the last half of 2002, I located more birds by flying 160

km x 144 km blocks with transects spaced 24 km apart. The size of these blocks was

occasionally altered due to time constraints, but the distance between transects was

consistent throughout the remainder of the study. After locating a signal, my pilot

recorded the location and immediately relayed the information to me on the ground.

The pilot was experienced in wildlife telemetry, so he screened each signal heard as a

good possibility or a questionable signal (e.g., due to signal strength, range, or pulse

rate.)

76

Once a radio signal was located from the air, I attempted to locate and flush

the bird to confirm that the signal was a radio-marked woodcock. Woodcock often

move up to 60 m in front of a researcher or bird dog before flushing (Dyer and

Hamilton 1977). To eliminate any difference between the initial location of the bird

and the flushing location, I triangulated the bird’s location from 10 m away while my

bird dog was kept at my side, then I sent the dog in to flush the radio-marked bird.

Habitat data, site description (see below), and the number of unmarked woodcock

flushed were recorded at the point of flush. Search effort for unmarked woodcock

was not equal between locations due to time constraints, property access, and cover

type. When time permitted, I monitored marked birds daily to determine stopover

duration. I considered radio-marked woodcock located south of 33° N latitude

(northern border of Louisiana) to be on the winter grounds, while birds located north

of this line were considered to be in migration.

If I was unable to relocate the signal when I arrived at the pilot's recorded

coordinates, then I searched a 5-km radius area with a truck-mounted, 5-element,

yagi-style antenna. If the signal was not found in the area, then the bird was

presumed to have resumed migration and the location was recorded as unconfirmed.

I used all radio-marked woodcock locations to create a fall migration route

map. I then used the migration routes, coupled with stopover duration, to identify

priority areas for future woodcock management in the Central Region.

Habitat

I recorded habitat data and site characteristics in a 30-m radius area centered at the

point of flush for each radio-marked bird. Cover type was classified using the

77

National Vegetation Classification System (Anderson et al. 1998). Size classes of

over-story trees were grouped into sapling (<7.5 cm diameter at breast height

(diameter at breast height (DBH)), pole (7.5 cm - 15 cm DBH), and mature (>15 cm

DBH). I recorded the 4 most prevalent species of ground vegetation (0 - 0.5 m) and

midstory vegetation (0.5 - 2 m). I recorded the horizontal density of the ground and

midstory vegetation in 4 cardinal directions by ranking the density on a scale of 1-5.

This equal interval scale was classified as: 1 -little or no standing vegetation, 2 - 20 –

40% cover, 3 - 40 – 60% cover, 4 - 60 – 80% cover, and 5 - nearly impenetrable

thicket with dense standing vegetation. I estimated canopy coverage, in 4 cardinal

directions, with a convex spherical densiometer (Lemmon 1957). Distance to the

nearest edge, edge type, and visual estimates of habitat patch size were recorded. I

defined edge as an abrupt change in habitat structure, such as a road, river, or clearcut

edge.

I determined soil texture by feel (Tinner 1999). In 2002, I ranked soil

moisture as dry, moist, or wet. In 2003, I collected soil samples with a cylinder 12.7

cm diameter by 8 cm deep; the maximum woodcock bill length (Keppie and Whitting

1994). After oven drying, the percentage moisture of the soil sample was calculated

by dividing the dry weight (g) by the wet weight (g).

Earthworm densities were estimated using a hot mustard extraction technique

(Gunn 1992, Lawrence and Bowers 2002). I removed all vegetation and leaf litter

from a 35 x 35 cm plot and evenly applied a solution of 78 ml oriental hot mustard

powder and 1 L of water. All earthworms that surfaced within 5 min of application

were collected and preserved in 4% formalin for 48 hr and then transferred to a 70%

78

alcohol solution. Earthworms are not evenly distributed in the soil (Poier and Richter

1992), so I collected three samples spaced 5 m apart at each woodcock location.

These samples were averaged to determine the earthworm density per m².

I was unable to find any documentation on the use of a soil penetrometer in

woodcock research. When studying woodcock, many biologists collect soil data such

as texture, moisture, and porosity. These are indirect measures of how easily a

woodcock can penetrate the soil. I used a Lang soil penetrometer to determine the

amount of pressure that is needed to penetrate the soil with a probe roughly the size

and shape of a woodcock beak. I collected 3 penetrometer readings adjacent to each

earthworm sampling plots. The values were converted from pounds per in² to kg/cm²

and then averaged to determine the average kg/cm² of earthworms for each sampling

plot.

I used the 1992 National Land Cover Data (NLCD) (U.S. Geological Survey

2003) in a Geographic Information System (GIS) to map potential woodcock habitat

in the Central Region. The NLCD was created from early to mid-1990s Landsat

Thematic Mapper satellite data. The NLCD is classified into 21 classes (Table 1) and

has a spatial resolution of 30 m. Using available spatial data, I was not able to map

habitat availability, but I was able to identify areas of no diurnal habitat (Table 1)

resulting in a map of potential woodcock habitat.

After mapping potential habitat, I overlaid 4 hypothesized migration routes

and 2 migration routes that I observed radio-marked birds using. The first 3

hypothesized migration routes were the shortest lines from each of the 3 northern

study areas to the winter grounds of central Louisiana. The other hypothesized route

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followed the Mississippi River from the breeding grounds to central Louisiana. An

ArcView script was used to create a point every 5 km along these routes. I then

calculated the percent potential habitat within a 50 km buffer of each point. Values

were then graphically displayed to show the change in potential habitat availability

along each migration route.

RESULTS

Sample Size

In Fall 2001, 64 radio-marked woodcock were censored from the Minnesota

field site. In Fall 2002, 274 radio-marked woodcock were censored from Michigan

(n=92), Minnesota (n=94), and Wisconsin (n=91). In Fall 2003, 244 radio-marked

woodcock were censored from Michigan (n=63), Minnesota (n=102), and Wisconsin

(n=79).

Telemetry

During Fall 2001 pilot season, I located 4 radio-marked woodcock while

scanning 64 frequencies on 3 flights (Fig. 4) totaling 24 hours. Three of the locations

were confirmed by flushing the radio-marked woodcock. During Fall 2002, I located

29 radio-marked woodcock while scanning for 235 frequencies on 16 flights totaling

125 hours (Fig. 5). Twenty-two of the locations were confirmed. During Fall 2003, I

located 9 radio-marked woodcock while scanning for 162 frequencies on 10 flights

totaling 75 hours (Fig. 6). Seven of the locations were confirmed. I flew a greater

number of flights in 2002 than in 2003 due to budgetary constraints.

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During 2001, woodcock were radio-marked only in Minnesota, so I know the

origin of birds located that year (Fig. 7). The origin of 18 of the relocated radio-

marked birds from 2002 was unknown because multiple birds were marked with

radios ≤ 0.007 MHz apart. Of the remaining relocated birds, 4 were from Wisconsin,

1 was from Michigan, and 5 were from Minnesota (Fig. 7). In 2003, the origin of 2 of

the relocated radio-marked birds was unknown due to drift in the pulse rate of our

radio transmitters. Of the remaining relocated birds, 3 were from Wisconsin, 1 from

Michigan, and 3 from Minnesota (Fig. 7). I often, flushed unmarked woodcock, up to

8, from the same forest stand as the radio-marked bird. Radio-marked woodcock

were never located again during migration or later on the winter grounds.

Of the possible radio-marked woodcock found in 2001, two were males and

two were females. Three of these were hatch year birds and one was an after

hatching year bird (Fig. 2). Of the locations in 2002, 10 were males, 14 were

females, and the sex of five was unknown. Eleven of the locations were hatch year

birds, five were after hatching year, and the age of 13 was unknown. In 2003, seven

of the marked-woodcock locations were females and two were unknown sex. Of the

nine locations, seven were after hatch year birds and 2 were unknown.

Migration Distance

I was able to record distance and estimated flight duration for 13 radio-marked

woodcock (Table 4). Two birds were found in Missouri and Illinois, 16 and 21 days

after they were last located on the breeding ground. Birds were found in southern

Arkansas 20 - 48 days after they were last located on the breeding ground. One bird

traveled from Wisconsin to northeastern Texas in <16 days, a total distance of 1406

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km. Five birds on the winter ground were found 22-41 days after they were last

located on the breeding ground.

Stopover Duration

I documented stopover durations of 24 radio-marked woodcock (Table 5). I

know the exact stopover duration of seven birds, possible stopover range of six, and

minimum stopover duration for 11. Four birds resumed migration on the day of

initial location, but 13 birds stopped over for > four days. The longest stopover

observed was a bird in northern Arkansas that stayed for 10-16 days before resuming

migration. The exact stopover duration of this bird was unknown because I was

unable to visit the site for 6 days. I observed the timing of migration initiation after

stopover in four cases. Two birds migrated before 1945, one before 2100, and one

after 2000.

Migration Habitat

I collected habitat data at 22 confirmed locations. Marked woodcock located

in or north of the Ozark Mountains (35º N) were found more often in upland

hardwood cover types (n=6) than in bottomland cover types (n=2) (Table 6). Marked

woodcock locations south of the Ozark Mountains were found more often in upland

pine or pine/hardwood cover types (n=9) than in bottomland cover types (n=4) (Table

6). Locations were found more often in mature (n=8) and sapling (n=10) size classes

than in pole (n=3) size class. Median habitat block size was 0.108 (SD 3.754, n=18)

km² with a range of 0.0007-15.37 km². Median distance of marked woodcock from

habitat edge was 14 m (SD 52.236, n=18) with a range of 0-230 m.

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Woodcock used habitat with ground densities ranging from 1-3.25 with a

mean of 1.98 (SD 0.778, n=18) and mode of 1 (Fig. 8). Ground vegetation was most

often herbaceous plant species, blackberry (Rubus spp.), greenbrier (Smilax spp.), and

Japanese honeysuckle (Lonicera japonica) (Table 7). Midstory densities ranged from

1-5 with a mean of 2.86 (SD 1.272, n=18) and median of 2.82 (Fig. 8). Blackberry,

loblolly pine (Pinus taeda), greenbrier, and herbaceous plant species were most often

found in the midstory vegetation (Table 7 ). Percentage canopy cover ranged from 0-

99.22% with a mean of 58.45% (SD 37.798) and median of 77.64% (Fig. 9).

I located marked woodcock in 7 different soil types including sandy loam

(n=5), clay loam (n=4), loam (n=3), silty clay loam (n=2), silt loam (n=2), silty clay

(n=1), and sandy clay loam (n=1). In 2003, percent soil moisture ranged from 13.2-

30.69% with a mean of 22.58% (SD 7.107, n=5). Earthworm densities ranged from

0-3.07 g/m² with a median density of 0.84 g/m² and mean of 1.37 g/m² (SD 1.509,

n=5). Soil hardness ranged from 2.41-4.37 kg/cm² with a mean hardness of 3.20

kg/cm² (SD 1.333, n=5) and median of 3.09 kg/cm².

Winter Habitat

Habitat data were collected at 10 confirmed winter locations. Wintering birds

were found more often in upland cover types (n=8) than in bottomland cover types

(n=2) (Table 6). Locations were more common in mature (n=5) and sapling (n=4)

size classes than in pole (n=1). I found blackberry, greenbrier, and oak species most

often in the midstory vegetation (Table 8) and blackberry and Japanese honeysuckle

most often in the ground vegetation (Table 8). Horizontal midstory densities ranged

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from 2.5-5 with a mean and median of 3.5 (SD 0.792). Ground densities ranged from

1-3, with a mean of 1.37 (SD 0.891) and a median of 1.25.

Wintering marked woodcock were present in 4 soil types: loamy sand (n=3),

sand (n=2), sandy loam (n=2), and silty clay loam (n=1). In 2003, percent soil

moisture at the two winter locations were 23.06% and 28.35%. Earthworm densities

were 1.58 g/m² and 0 g/m². Soil hardness was 1.25 kg/cm² and 2.40 kg/cm².

Fall Migration Routes

Using my sample of radio-marked woodcock locations, I mapped 2 possible

fall migration routes: 1) Ozark Route and 2) Mississippi Route (Fig. 10). The 2

possible routes from Minnesota, Wisconsin, and Upper Peninsula Michigan

converged on the Mississippi River as they headed south into Iowa and Illinois. In

east-central Missouri, the Ozark Route birds headed south through the Ozark

Mountains until they reached the pinelands of the Gulf Coastal Plain. Once they

reached the pinelands, they eventually spread out and worked their way south

throughout the pinelands of western and central Louisiana and eastern Texas. A

smaller percentage of the birds used the Mississippi Route through the Bootheel of

Missouri, over the northern portion of the lower Mississippi Alluvial Valley (MAV),

and then followed the bluff edge of the MAV south into Mississippi.

Potential Habitat Map

Several areas in the Central Region had a limited amount of potential diurnal

woodcock habitat (Fig. 11). The first area was the agriculture/grassland-dominated

areas of southern Minnesota, Iowa, northern Illinois, northern Indiana, and western

Ohio. On the western edge of the woodcock’s range there was limited potential

84

habitat in the Dakotas, Nebraska, and Kansas, but potential habitat increased in

Oklahoma and Texas. There was also limited potential habitat throughout the MAV.

Within the MAV, the amount of potential habitat increased from north to south.

Extensive potential habitat existed in the northern half of the Great Lakes states, in

the Ozark Highlands of Missouri and Arkansas, the West Gulf Coastal Plain of

southern Arkansas, western Louisiana, and eastern Texas, and throughout Kentucky,

Tennessee, Mississippi, and Alabama. On the winter grounds in Louisiana, potential

habitat was highest in the upland areas in the west central, north central, and areas

north of Baton Rouge and Lake Pontchatrain.

DISCUSSION

Woodcock use early successional habitat almost exclusively on the breeding

grounds and a wider range of early successional and mature forests on the wintering

grounds (Cade 1985, Keppie and Whitting 1994, Straw et al. 1994), but the point in

migration at which they start using mature forest is unknown. The first woodcock

that I found using mature forests were in Illinois and Missouri where mature oak

forest was used. I also found woodcock in mature forest further south in Arkansas,

Mississippi, Louisiana, and Texas.

Historically, mature forests used on the wintering ground are thought to have

a distinct understory (Keppie and Whitting 1994). Understories least prefer by

woodcock are extremely dense or open habitats (Cade 1985). The southern locations

I found were usually in pinelands or hardwoods with a developed understory, whereas

the mature forest locations in Missouri and Illinois were void of an understory.

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Although the majority of radio-marked woodcock locations were in moderately dense

habitats, some locations were found in extremely dense or open habitats.

On the winter grounds, woodcock are thought to primarily use bottomland

areas and secondarily use pineland areas (Roberts 1993, Straw et al. 1994). During

migration and on the winter grounds, I found most locations in upland oak, pine, or

pine/hardwood forests. Managers could have underestimated the importance of these

habitats.

When moisture is limited, pineland areas, mixed pine-hardwood stands,

hardwood drainages, and bottomlands provide more suitable habitat than

predominantly pine areas (Boggus and Whiting 1982). Researchers studying

woodcock habitat selection on the winter grounds have found that woodcock using

pinelands are often associated with riparian hardwood drainages located within a pine

stand (Roberts 1993). Eight of my locations were associated with these riparian strips,

while 9 locations were not associated with any type of drainage. During my study,

the Palmer Drought Index (N.O.A.A. 2004) never fell into significant drought

conditions in the southern Central Region. Thus, the habitat types used by marked

birds were probably reflective of normal weather conditions. Use of bottomland

hardwood stands may be restricted to periods of drought (Krementz and Pendleton

1994, Krementz 2000) or during later winter (M. Olinde, Louisiana Department of

Wildlife and Fisheries, personal communication).

During spring and summer, woodcock mostly feed during diurnal hours

(Keppie and Whitting 1994), however during winter they feed extensively at night

(Krementz et al. 1995). Some birds were located during the day in dry soil habitats

86

with no available earthworms, so migratory woodcock might be feeding primarily in

their nocturnal habitats.

On the winter grounds, woodcock prefer nocturnal block sizes from 0.05 – 0.4

km² (Krementz 2000). I found median stand size at diurnal migrating woodcock

locations of 0.108 km². Within these stands, woodcock were most often found

associated with a habitat edge. Of 28 confirmed locations, 36% were ≤ 10 m from an

edge and 86% were ≤ 50 m from an edge. Possible explanations of the association

with edge might have been caused by highly fragmented landscapes, differences in

vegetation structure near edges, or due to my consideration of a stream as an edge.

Habitat availability might have been limited in certain parts of the migration

route. Making a series of short flights is energetically cheaper than covering the same

distance in one long flight (Piersma 1987). Migrating shorebirds are thought to make

longer flights when the availability of quality habitat is limited (Piersma 1987).

Expansive areas of limited habitat could have been “ecological barriers” requiring

non-stop flights. Further research is needed to determine if woodcock are migrating

over areas of low habitat availability.

During fall migration, woodcock initially encountered an expansive area of

minimal potential habitat in Iowa, northern Illinois, and northern Indiana. Birds that

migrated from the 3 northern study sites, potentially had to travel 600-800 km before

reaching areas of expansive potential habitat in central Missouri and southern Illinois.

The MAV is another expansive area of limited potential habitat, especially compared

with the amount of habitat that was historically available.

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Coon et al. (1976) documented 2 woodcock stopping over after an initial

nocturnal migration flight and then resuming fall migration the following evening.

The stopover durations I observed were much longer than Coon et al.’s observations.

There are two possible explanations for the difference in stopover durations. Coon et

al’s (1976) observations were both on the initial leg of fall migration that might not

be representative of true migration. An alternative explanation would be that these

birds were experiencing migratory restlessness. Krementz et al. (1994) documented

migratory restlessness when woodcock moved out of their study area before

commencing spring migration.

I was unable to monitor all birds until they resumed migration and my

stopover durations did not include the time that the radio-marked bird spent at the

location before my locating it. So, stopover durations are most likely longer than I

observed (Kaiser 1999, Lehnen 2004). Average stopover is probably greater than a

few days and often over a week.

There are two competing hypothesis proposed to explain the time that a

migrant bird spends at a stopover location: 1) time-selection (Alerstam and

Lindstrom 1990) and 2) energy-selection (Gudmundsson et al. 1991). Under the

time-selection hypothesis, the migrant minimizes its total migration time by passing

lower quality stopover sites. Under the energy-selection hypothesis, the migrant will

travel to the next stopover site as soon as it has the energy to do so, regardless of the

quality of the site. Migrants operating under the time-selection hypothesis would

spend less time at high quality sites, where as migrants would spend more time at

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high quality sites under the energy-selection hypotheses. Further research is needed

to determine which mechanisms determine the stopover duration of woodcock.

Woodcock have the shortest migration distance of 37 shorebird species found

in the central U.S. (Skagen 1997). Furthermore, they are the only North American

shorebird with rounded rather than pointed wings (Sheldon 1967), making

continuous, cross-continent flights unlikely. I found radio-marked woodcock in the

mid-latitude states of the Central Region, so they were not migrating from the

breeding grounds to the wintering grounds in one large jump. I observed long

stopover durations, so woodcock were probably not migrating in many short flights

followed by short stopovers. Long stopover durations suggests that woodcock are

migrating in several long flights followed by extended periods of refueling.

Unlike migrating songbirds, shorebirds are thought to follow fixed routes

during migration, although these routes are more defined in coastal areas (Skagen

1997). Woodcock are found throughout the Central Region during migration, but

certain migration routes have much higher densities of migrants (Glasgow 1958). I

proposed 2 possible migration routes (Ozark and Mississippi Route) used by radio-

marked woodcock due to the spatial pattern of marked woodcock locations. After

flying 224 hours of telemetry flights in the Central Region, certain areas were

continuously void of radio-marked woodcock while other areas contained radio-

marked birds. My possible woodcock fall migration routes differed from those of

Glasgow (1958) and Sheldon (1967), mainly due to the lack of radio-marked bird

locations in the MAV. Loss of bottomland habitats within this area apparently has

89

caused a shift in woodcock migration routes. Migration routes that historically

passed through the MAV might have shifted to the valley edges to avoid this area.

The majority of radio-marked woodcock locations were along the Ozark

Route through central Missouri and central Arkansas. After crossing Iowa and

Illinois, potential habitat availability increased continuously to near 90% on the

winter grounds (Fig. 12). The Mississippi Route peaked near 90% in southeastern

Missouri but then dropped temporarily while crossing the MAV (Fig. 13). The two

observed migration routes (Ozark and Mississippi Routes) had greater densities of

potential habitat than straight lines between the 3 study sites and south central

Louisiana (Fig. 14 -16) and the route following the Mississippi River (Fig. 17).

I used the straight-line distance from each northern study area as hypothesized

routes because many migrant shorebirds take the shortest route between breeding and

winter grounds (Farmer and Parent 1997). I used the Mississippi River as the fourth

hypothesized migration route because Coon et al. (1976) observed radio-marked

woodcock migrating in a direction that coincided with a river valley. The 4

hypothesized migration routes ended in south central Louisiana because that is where

the highest densities of overwintering woodcock were historically thought to occur

(Glasgow 1958). My 2 observed routes (Ozark and Mississippi Routes) ended in the

pinelands of Louisiana and Mississippi because I did not locate any radio-marked

woodcock south of those locations. Due to the battery life of my radios, I could not

monitor the location of my birds through the winter, so I cannot be certain that the

birds in Texas, Louisiana, and Mississippi had arrived at their final winter locations.

90

Regardless of whether or not they were wintering, I have shown that these pineland

locations are important to woodcock.

Sheldon (1967) reported that woodcock mainly winter in southeastern

Arkansas, Louisiana, and south-western Mississippi. Owen et al. (1977) reported

that woodcock breeding west of the Appalachian Mountains winter in Arkansas,

Louisiana, Mississippi, and Alabama. Root (1988) analyzed Christmas Bird Count

data and found the greatest densities of wintering woodcock in east Texas near Sam

Rayburn and Toledo Bend Reservoirs. Straw et al. (1994) analyzed Christmas Bird

Count Data and reported that wintering woodcock are common to abundant in south

Louisiana and east Texas, scattered to common in southeast Mississippi, north

Louisiana, south and east Arkansas, east Texas, southeast Missouri, and west

Kentucky and Tennessee. Straw et al. (1994) concluded that woodcock wintering

range in the central region extends to central Missouri. I used 33º N latitude as the

northern extent of the primary wintering range due to banding records and

observations of radio-marked woodcock in Arkansas (see below). There is no

definitive boundary to the winter range. Woodcock probably winter in low densities

in southern Arkansas and northern Mississippi in some years and are absent in others.

Despite these few birds that overwinter north of traditional areas, most woodcock

winter farther south and arrive at their wintering location by 15 December. Of the

woodcock banded in Minnesota, Michigan, and Wisconsin and directly recovered

from 16-31 December 1929-2001 (n=26), 92.3% were south of 33º N latitude. This

same pattern is seen when looking at all Central Region direct recoveries during this

period (93.1%, n=98)) and all woodcock direct recoveries west of the Atlantic Coastal

91

States (89.7%). Of the 8 birds in southern Arkansas that I was able to monitor for

about a week after location, 6 resumed migration. The other 2 were present after 1

week.

In Louisiana, woodcock densities were historically thought to be highest in the

bottomland areas of south-central Louisiana (Glasgow 1958, Britt 1971, Straw et al.

1994, M. Olinde, Louisiana Department of Wildlife and Fisheries, personal

communications). In 2002 and 2003, I searched for radio-marked birds throughout

Louisiana and east Texas (6 - 20 December), but my only locations were in the

pinelands and associated bottomlands of the Gulf Coastal Plain (Fig. 7). Managers

could have underestimated the importance of this region to migrating and over-

wintering woodcock.

MANAGEMENT IMPLICATIONS

Many species of shorebirds in the central U.S. use traditional stopover

locations where a large percent of the population may stop in a given year (Farmer

and Parent 1997). From my telemetry data it appears that woodcock are not

concentrating at major stopover locations. They are most likely opportunistically

selecting stopover locations at the end of each night’s flight. Therefore, in the Central

Region, I identified large geographic areas of importance to migrating woodcock.

Based on densities of radio-marked woodcock locations, I identified four

locations as priority areas for consideration of future woodcock management in the

Central Region (Fig. 18). To determine high priority areas, I located areas that had the

highest densities of radio-marked woodcock locations and areas with moderate

92

densities to determine medium level priority areas. The first area was the southern

pinelands of Arkansas. This high priority area was centered on the Saline River and

dominated by industrial pinelands with lowlands of bottomland hardwoods.

Surrounding this area was a medium level priority area in which I located a few

radio-marked woodcock and the habitat was similar to that of the high priority area.

A medium level priority area was located in northeastern Missouri and west

central Illinois where the Mississippi, Illinois, and Missouri Rivers converge. This

funnel area concentrated birds from Minnesota, Wisconsin, and Upper Peninsula

Michigan. This area was a potential stopover site after a migration flight over

predominantly grassland/agriculture areas of Iowa and Illinois.

Another medium level priority area was the pinelands of northern Mississippi

along the bluff edge of the MAV. I selected this area because it was a possible funnel

area between the agricultural dominated lands of the MAV to the west and the

Tombigbee River Valley to the east. This area was a potential stopover after birds

crossed the primarily agricultural area of the MAV. Woodcock migrating from the

eastern half of the Central Region may have passed through this area also.

Two high priority areas were on the wintering grounds. One was the

pinelands of north-central Louisiana between the MAV and the Red River and the

second was the pinelands of western Louisiana and eastern Texas between the Red

River and Sam Rayburn Reservoir. A medium level priority area that covers the

pinelands of western Louisiana and eastern Texas surrounded these two areas.

Although I did not find many marked woodcock within this area, habitat conditions

are similar to those of the wintering high priority areas.

93

Expansive areas of no potential habitat should also be considered as

management priority areas, especially those that lie along possible migration routes.

Two of these areas were lands adjacent to the Mississippi River in Iowa and Illinois

and parts of the MAV in southeastern Missouri and northeastern Arkansas.

My observations of long stopover durations suggest that woodcock

populations would greatly benefit from habitat acquisition and proper management

within priority areas and along migration routes. Further research is needed to

develop best management practices for woodcock during fall migration in the Central

Region. Managers should also consider further investigations of woodcock wintering

distribution and the importance of southern pineland habitats to migrating and

wintering woodcock.

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chronology, and future projections of bottomland hardwood habitat loss in the lower Mississippi Alluvial Plain. Volume 1, Basic Report. HRB-Singer, Incorporated, State College, Pennsylvania, USA.

Martin, F. W. 1964. Woodcock age and sex determination from wings. Journal of

Wildlife Management 28:287-293. McAuley, D. G., J. R. Longcore, and G. F. Sepik. 1993. Techniques for research into

woodcock: experiences and recommendations. Pages 5 –11 in J. R. Longcore and G. F. Sepik, editors. Eighth Woodcock Symposium. U.S. Fish and Wildlife Service, Wildlife Resource Report.

______, J. R. Goldsberry, J. R. Longcore. 1993. Omnidirectional aircraft antennas

for aerial telemetry. Wildlife Society Bulletin 21:487-491. Murphy, D. W. 1983. Ecology of American woodcock in central Missouri. Thesis, University of Missouri, Columbia, Missouri, USA. National Oceanic and Atmospheric Administration. 2004. Drought Information

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Mississippi Valley. Restoration and Management 8:23-28. Owen, R. B., Jr. 1977. American woodcock. Pages 149-186 in G. C. Sanderson,

editor. Management of migratory shore and upland game birds in North America. International Association of Fish and Wildlife Agencies, Washington, D.C., USA.

Piersma, T. 1987. Hop, skip, or jump? Constraints on migration of arctic waders by feeding, fattening, and flight speed. Limosa 60:185-194. Poier, K. R., and J. Richter. 1992. Spatial distribution of earthworms and soil

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Roberts, T. H. 1978. Migration, distribution, and breeding of American woodcock. Tennessee Wildlife Resources Agency, Technical report 79. _____. 1993. The ecology and management of wintering woodcocks. Biological Report 16:87-97.

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Root, T. 1988. Atlas of wintering North American birds. An analysis of Christmas Bird Count data. University of Chicago Press, Chicago, Illinois, USA.

Sepik, G. F., and E. L. Derleth. 1993. Premigratory dispersal and fall migration of American woodcock in Maine. Biological Report 16:36-40. Sheldon, W. G. 1967. The book of the American woodcock. University of Massachusetts Press, Amherst, Massachusetts, USA. Skagen, S. K. 1997. Stopover ecology of transitory populations: The case of

migrant shorebirds. Ecological Studies 125:244-269. Straw, J. A., Jr., D. G. Krementz, M. W. Olinde, and G. F. Sepik. 1994. American

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http://landcover.usgs.gov/natllandcover.asp

Figure 1. Woodcock management regions determined by Coon et al. (1977) using band recovery data.

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Figure 2. Possible American woodcock fall migration route proposed by Glasgow (1958) and Sheldon (1967) using band return data.

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Figure 3. Location of study areas where woodcock were radio-marked by the University of Minnesota, University of Wisconsin, and Northern Michigan State University from 2001-2003.

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Figure 4. Flight paths of 3 radio-telemetry searches flown in Fall of 2001 for woodcock radio-marked in Minnesota. See Table 3 for corresponding flight dates and durations. All flights originated in Bald Knob, AR.

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Figure 5. Flight paths of 16 radio-telemetry searches flown in Fall of 2002 for woodcock radio-marked in Michigan, Minnesota, and Wisconsin. See Table 2 for corresponding flight dates and durations. All flights originated in Bald Knob, AR.

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Figure 6. Flight paths of 10 radio-telemetry searches flown in Fall of 2003 for woodcock radio-marked in Michigan, Minnesota, and Wisconsin. See Table 2 for corresponding flight dates and durations. Flights 1 and 2 originated in Ames, IA, all other flights originated in Bald Knob, AR.

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Figure 7. Location and origin of all radio-marked woodcock locations from 2001-2003. The origin of some radio-marked birds was unknown due to multiple birds being marked with radio transmitters ≤0.007 MHz apart. Confirmed locations are those where I was able to locate and flush the bird on the ground. Locations north of 33º N latitude were classified as migratory while those south of this line were considered to be on the winter grounds

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0

1

2

3

4

5

6

7

1 2 3 4 5

Mid-story Density

Freq

uenc

y

0

1

2

3

4

5

6

7

8

9

10

1 2 3 4 5

Ground Density

Freq

uenc

y

Figure 8. Frequency of ground and mid-story vegetation horizontal density at confirmed migrating marked woodcock locations (n=18) in 2002 and 2003. Density was visually estimated on a scale of 1 (sparse) - 5 (dense).

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0

1

2

3

4

5

6

7

8

9

10

0 - 20 20 - 40 40 - 60 60 - 80 80 - 100

Canopy (%)

Freq

uenc

y

Figure 9. Frequency of percent canopy cover at all confirmed migrating marked woodcock locations (n=18) in 2002 and 2003.

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Figure 10. Possible woodcock fall migration routes used by woodcock radio-marked from 2001-2003 in Minnesota, Wisconsin, and Upper Peninsula Michigan. The route through northeast Arkansas and the route through southern Illinois are two routes that I suspected but only found minimal evidence.

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Figure 11. Central Region potential woodcock habitat determined from 1992 National Land Cover Data (NLCD). Potential woodcock habitat includes NLCD classifications: woody wetlands, shrubland, deciduous forest, evergreen forest, mixed forest, orchard/vineyard/other, and transitional.

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0

0.1

0.2

0.3

0.4

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0.9

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42.5

41.6

40.8

39.9

39.0

38.1

37.3

36.4

35.5

34.6

33.7

32.9

32.0

Latitude

Perc

enta

ge

Figure 12. Percent potential woodcock habitat availability along a 50-km buffered fall migration route (inset) that I observed radio-marked woodcock using from 2001 - 2003. Potential woodcock habitat included 1992 National Land Cover Data classifications: woody wetlands, shrubland, deciduous forest, evergreen forest, mixed forest, orchard/vineyard/other, and transitional.

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0

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0.4

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0.7

0.8

0.9

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42.5

41.6

40.8

39.9

39.0

38.1

37.3

36.4

35.5

34.6

33.8

32.9

32.0

Latitude

Perc

enta

ge

Figure 13. Percent potential woodcock habitat availability along a 50-km buffered fall migration route (inset) that I observed radio-marked birds using from 2001 to 2003. Potential woodcock habitat included 1992 National Land Cover Data classifications: woody wetlands, shrubland, deciduous forest, evergreen forest, mixed forest, orchard/vineyard/other, and transitional.

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0

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45.7

44.8

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42.2

41.3

40.5

39.6

38.7

37.9

37.0

36.1

35.2

34.4

33.5

32.6

31.7

30.9

Latitude

Perc

enta

ge

Figure 14. Percent potential woodcock habitat availability along a 50-km buffered fall migration route (inset) directly from the Michigan field site to central Louisiana. Potential woodcock habitat included 1992 National Land Cover Data classifications: woody wetlands, shrubland, deciduous forest, evergreen forest, mixed forest, orchard/vineyard/other, and transitional.

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0

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44.8

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41.3

40.4

39.5

38.6

37.7

36.8

35.9

35.1

34.2

33.3

32.4

31.5

Latitude

Perc

enta

ge

Figure 15. Percent potential woodcock habitat availability along a 50-km buffered fall migration route (inset) directly from the Minnesota field site to central Louisiana. Potential woodcock habitat included 1992 National Land Cover Data classifications: woody wetlands, shrubland, deciduous forest, evergreen forest, mixed forest, orchard/vineyard/other, and transitional.

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0

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45.4

44.5

43.6

42.7

41.9

41.0

40.1

39.2

38.3

37.4

36.5

35.6

34.7

33.9

33.0

32.1

31.2

Latitude

Perc

enta

ge

Figure 16. Percent potential woodcock habitat availability along a 50-km buffered fall migration route (inset) directly from the Wisconsin field site to central Louisiana. Potential woodcock habitat included 1992 National Land Cover Data classifications: woody wetlands, shrubland, deciduous forest, evergreen forest, mixed forest, orchard/vineyard/other, and transitional.

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0

0.1

0.2

0.3

0.4

0.5

0.6

42.5

41.7

41.0

40.2

39.4

38.7

37.9

37.1

36.3

35.6

34.8

34.0

33.2

32.5

31.7

30.9

Latitude

Perc

enta

ge

Figure 17. Percent potential woodcock habitat availability along a 50-km buffered fall migration route (inset) following the Mississippi River to central Louisiana. Potential woodcock habitat included 1992 National Land Cover Data classifications: woody wetlands, shrubland, deciduous forest, evergreen forest, mixed forest, orchard/vineyard/other, and transitional.

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Figure 18. Woodcock management priority areas in the Central Region that I designated based on locations of radio-marked woodcock. High priority areas were identified because of the high density of radio-marked woodcock locations from 2001-2003. Medium priority areas had fewer radio-marked woodcock locations but they contained similar habitat conditions as high priority areas, were funnel areas along migration routes, or were areas of suitable habitat after large expanses of limited potential habitat.

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Table 1. 1992 National Land Cover Data land cover classifications used in mapping potential woodcock habitat in the Central Region. Potential habitats are those that possibly provide diurnal woodcock habitat.

Potential Habitat Cover-types

Shrubland

Woody Wetland

Deciduous Forest

Evergreen Forest

Mixed Forest

Orchards/Vineyards/Other

Transitional

No Potential Habitat Cover-types

Open Water

Perennial Ice/Snow

Bare Rock/Sand/Clay

Quarries/Strip Mines/Gravel Pits

Grassland/Herbaceous

Emergent Herbaceous Wetland

Low Intensity Residential

High Intensity Residential

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Commercial/Industrial/Transportation

Pasture/Hay

Row Crops

Small Grain

Fallow

Urban/Recreational Grasses

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Table 2. Sex and age of confirmed and unconfirmed radio-marked woodcock locations from 2001-2003. The sex and age of some birds was unknown due to multiple radio transmitters with frequencies ≤ .007 MHz apart. Age was recorded as hatch year (HY) or after hatching year (AHY).

Year Recovery Location Sex Age Confirmed

2001 Crossett, AR F HY Yes

Felsenthal, AR F HY No

Hope, AR M AHY Yes

Prescott, AR M HY Yes

2002 Adona, AR M AHY Yes

Atlanta, TX F HY Yes

Batchtown, IL M AHY Yes

Belfast, AR F Unknown Yes

Brookeland, TX M Unknown Yes

Burkeville, TX M HY No

Clayton, TX M HY Yes

Curtis, TX F HY No

De Ridder, LA F HY Yes

Fordyce, AR Unknown Unknown Yes

Fort Polk, LA F Unknown No

Fredricktown, MO M Unknown Yes

Grapevine, AR Unknown Unknown Yes

Grenada, MS F AHY Yes

Gunn, MS F Unknown Yes

Hannibal, MO Unknown Unknown No

Iberia, MO F AHY Yes

Jasper, TX F Unknown No

Lebanon, MO M HY Yes

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Montrose, AR F HY No

Natchitoches, LA M HY Yes

Paragould, AR Unknown HY Yes

Ruston, LA F HY Yes

Sikes, LA Unknown Unknown Yes

Tarry, AR F HY Yes

Warren, AR F Unknown Yes

West, MS M Unknown Yes

Winchester, IL F Unknown No

Winnfield, LA M AHY Yes

2003 Alexandria, LA F AHY Yes

Columbia, MO F AHY No

Dennard, AR F AHY Yes

Jefferson City, MO Unknown AHY Yes

Pickneyville, IL Unknown Unknown Yes

Pollock, LA F AHY Yes

Rison, AR F AHY Yes

Star City, AR F Unknown Yes

Farber, MO F AHY No

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Table 3. Date and duration of radio-telemetry flights flown from 2001-2003 searching for radio-marked woodcock. Flight numbers correspond to flight routes maps (Fig. 2-4).

Year Flight

Number Date Duration (hours)

2001 1 9 Nov 4.2

2 20 Nov 5.8

3 4 Dec 10

2002 1 1 Nov 7

2 2 Nov 6

3 7 Nov 6.7

4 8Nov 6.3

5 17 Nov 6.8

6 18 Nov 5

7 20 Nov 5.9

8 22 Nov 5.3

9 25 Nov 9.8

10 27 Nov 8.8

11 29 Nov 9.8

12 6 Dec 8.8

13 7 Dec 9

14 16 Dec 9.5

15 17 Dec 9.8

16 20 Dec 10.5

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2003 1 1 Nov 6.5

2 7 Nov 7.2

3 10 Nov 8.6

4 19 Nov 6.4

5 20 Nov 7.1

6 21 Nov 8

7 26 Nov 6.9

8 6 Dec 8.7

9 7 Dec 6.7

10 9 Dec 8.9

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Table 4. Straight-line migration distances (km) and flight duration of all confirmed, known origin radio-marked woodcock from 2001-2003. Estimated flight duration was the time between the date that the bird was last located on the breeding ground and the date that the bird was located during migration.

Nearest Town Origin Trip

Length (km)

Max. Flight Duration (days)

km/days

Batchtown, IL MN 784 21 37.33

Iberia, MO MI 978 16 61.13

Dennard, AR WI 1096 15 73.07

Prescott, AR MN 1346 48 28.04

Hope, AR MN 1368 34 40.24

Rison, AR MI 1410 20 70.50

Crossett, AR MN 1429 30 47.63

Atlanta, TX WI 1406 16 87.88

Clayton, TX WI 1528 30 50.93

Natchitoches, LA WI 1536 41 37.46

Alexandria, LA WI 1554 32 48.56

Pollock, LA MN 1607 22 73.05

De Ridder, LA MN 1693 39 43.41

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Table 5. Stopover durations of radio-marked woodcock located during migration from 2001-2003. Stopover data were recorded only for birds that we were able to monitor for ≥1 day after locating them.

Recovery Site Date LocatedStopover Duration

Montrose, AR* 6 Dec, 2002 1

Prescott, AR 20 Nov, 2001 1

Star City, AR 20 Nov, 2003 1

Winchester, IL* 1 Nov, 2002 1

Grenada, MS 29 Nov, 2002 >1

Paragould, AR 17 Nov, 2002 >1

Adona, AR 20 Nov, 2002 1 - 2

Grapevine, AR 22 Nov, 2002 1 - 3

Hannibal, MO 17 Nov, 2002 2

Crossett, AR 1 Dec, 2001 >2

Hope, AR 4 Dec, 2001 >2

Fredericktown, MO 8 Nov, 2002 >3

West, MS 29 Nov, 2002 >3

Iberia, MO 7 Nov, 2002 4

Batchtown, IL 1 Nov, 2002 >4

Jefferson City, MO 7 Nov, 2003 >4

Pinckneyville, IL 10 Nov, 2003 >4

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Pollock, AR 7 Dec, 2003 >4

Tarry, AR 28 Nov, 2002 4 - 6

Lebanon, MO 7 Nov, 2002 5

Fordyce, AR 27 Nov, 2002 5 - 7

Belfast, AR 26 Nov, 2002 >8

Rison, AR 20 Nov, 2003 6 - 16

Dennard, AR 19 Nov, 2003 10 - 14

* Radio-marked woodcock locations where the radio signal was not confirmed by flushing the woodcock due to the bird migrating between the time the pilot located the signal and when I arrived at the location.

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Table 6. National Vegetation Classification System (NVCS) forest alliances at all confirmed marked woodcock locations from 2001-2003. Migration locations were divided between the oak-hickory dominated areas in and north of the Ozark Mountains (35º N) and predominately pine areas south of the Ozark Mountains, while wintering locations were south of 33º N latitude.

Migration locations in or north of the Ozark Mountains Frequency Eastern Red Cedar (Juniperus virginiana)- Quercus Forest Alliance 2

Post Oak (Quercus stellata)- Blackjack Oak (Quercus marilandica) Forest Alliance 2

Regenerating Old Field- Sumac¹ (Rhus spp.) 1

White Oak (Quercus alba) Forest Alliance 1

Overcup Oak (Quercus lyrata) Seasonally Flooded Forest Alliance 1

Pin Oak (Quercus palustris) Seasonally Flooded Forest Alliance 1

Migration Locations south of the Ozark Mountains Loblolly Pine (Pinus taeda)- Shortleaf Pine (Pinus echinata) Forest Alliance 8

Quercus Temporary Flooded Forest Alliance 2

Loblolly Pine (Pinus taeda)- Quercus Forest Alliance 2

Sweetgum (Liquidambar spp.) Temporary Flooded Forest Alliance 1

Loblolly Pine (Pinus taeda)- Temporary Flooded Forest Alliance 1

Winter Locations Loblolly Pine (Pinus taeda)- Shortleaf Pine (Pinus echinata) Forest Alliance 5

Loblolly Pine (Pinus taeda)- Quercus Forest Alliance 1

Old Field- Chinese Privet² (Lingustrum sinense) 1

Southern Red Oak (Quercus falcata) Forest Alliance 1

Quercus Temporary Flooded Forest Alliance 1

Sweetgum (Liquidambar spp.) Temporary Flooded Forest Alliance 1

Two locations did not fit into a NVCS vegetation class: ¹One radio-marked bird located in west-central Illinois was located in an old field that had regenerated into sumac (Rhus spp.). ²One radio-marked bird located in north-east Texas was located in an old field that had regenerated in a dense stand of Chinese Privet (Lingustrum sinense). Table 7. Dominant ground and mid-story vegetation species at migrating confirmed marked woodcock locations north of 33º N latitude from 2001-2003.

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Table 7. Dominant ground and mid-story vegetation species at confirmed marked woodcock locations north of 33º N latitude from 2001-2003.

Ground Species Frequency Herbaceous spp. (non-woody vegetation) 10

Blackberry (Rubus spp.) 5

Greenbrier (Smilax spp.) 4

Japanese Honeysuckle (Lonicera japonica) 3

Coral berry (Symphoricarpos orbiculatus) 2

Oak (Quercus spp.) 2

Rose (Rosa spp.) 2

American Holly (Ilex opaca) 1

Chinese Privet (Ligustrum sinense) 1

Loblolly Pine (Pinus taeda) 1

Mid-story Species Frequency Blackberry (Rubus spp.) 7



Herbaceous spp. (non-woody vegetation) 4


Elm (Ulmus spp.) 3

Sumac (Rhus spp.) 3


Deciduous Holly (Ilex decidua) 2


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Rose (Rosa spp.) 2

Sweetgum (Liquidambar styraciflua) 2

American Holly (Ilex opaca) 1

Autumn Olive (Elaegnus umbellata) 1

Eastern Redcedar (Juniperus virginiana) 1

Persimmon (Diospyros virginianas) 1

Red Maple (Acer rubrum) 1

Sweetbay (Ilex spp.) 1

Switchcane (Arundinaria gigantea) 1

Blueberry (Viburnum spp.) 1

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Table 8. Dominant ground and mid-story vegetation species at confirmed marked woodcock locations south of 33º N latitude from 2001-2003.

Mid-story Species Frequency Oak (Quercus spp.) 6

Blackberry (Rubus spp.) 4



Elderberry (Sambucus spp.) 3



Trumpet Creeper (Campsis radicans) 2

Herbaceous spp. 1

Sweetgum (Liquidambar styraciflua) 1

Longleaf Pine (Pinus palustris) 1

Grapevine (Vitis spp.) 1

Eastern Baccharis (Baccharis halimifolia) 1

Red Maple (Acer rubrum) 1

Ground Species Frequency Blackberry (Rubus spp.) 6




Herbaceous spp. 2

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Elderberry (Sambucus spp.) 1

AMERICAN WOODCOCK FALL MIGRATION ECOLOGY IN THE … · The American woodcock, Scolopax minor, is a...

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