Wildlife Ecologyand

Forest Habitat

EB1866

Illustrations

Lorraine Ashland

Authors

Janean H. Creighton, M.S., WildlifeExtension Coordinator

Washington State University Cooperative ExtensionDepartment of Natural Resource Sciences

Pullman, Washington

David M. Baumgartner, Ph.D.Extension Forester

Washington State University Cooperative ExtensionDepartment of Natural Resource Sciences

Pullman, Washington

Helping You Put Knowledge To Work

Habitat is “the physical and biological surroundings of an organism.” Good wildlife habitat suppliesall the elements an animal needs for survival. These elements include food, cover, water, and space.However, each animal varies in its requirement of these elements. When wildlife biologists and man-agers design programs to improve wildlife habitat, they take into account all the plants and animalsthat may be affected by their decisions.

Wildlife populations in forested habitats are dynamic because the forest is always changing. Plantsuccession, or the gradual replacement of one plant community with another, is an important aspectof wildlife habitat. Every successional plant stage, or habitat type, has a specific community of ani-mals associated with it. Close relationships among animals and environments illustrate how alter-ations to the habitat dramatically affect wildlife populations. This publication provides basic informa-tion about wildlife ecology and presents ideas on improving forested habitats for wildlife.

A Brief History

Before the 1960s, wildlife manage-ment focused primarily on maintaininggame animals, such as deer, elk, andgrouse. As knowledge evolved aboutthe interactions of animal and plantcommunities, wildlife agencies be-came concerned with nongame ani-mals. Animals such as songbirds andamphibians can be as important to ahealthy and fully functioning ecosys-tem as big game species are. Today,wildlife managers base decisions onbiological information gained fromscientific field and laboratory studies.Managers are learning more aboutthe complex relationships amonganimals and their environments.They need scientifically basedinformation to make intelli-gent management decisions.

Wildlife Ecology and Forest Habitat

Animals and Their Environment

Animals are closely linked to their environment. Bothliving and nonliving components influence their lives.Factors such as climate, soil, topography, and geographiclocation determine the composition and distribution of theplant and animal communities. Within these communities,plant species help determine the species of wildlife that arepresent. Also, the interaction among animals, that is, thecompetition for resources such as food, space, or mates, alsoinfluences wildlife populations. Because of these relation-ships, the best way to manage wildlife is to manage thehabitats in which they live.

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Landscape Ecology

Figure 1. A distinct plant community makesup each successional stage.

One important concept in habitat managementis landscape ecology. We usually look at wildlifehabitat on a relatively small scale, such as an indi-vidual forest stand. Landscape ecology views wild-life habitat on a much larger scale: such as a na-tional forest, a mountain range, or an entire region.The reason for this landscape approach is simple:many wildlife species move regularly because ofseasonal changes in food supply. Therefore,changes in habitat over a much wider range affectsome wildlife populations directly.

Viewing wildlife on a regional scale may notbe practical, or even necessary for a private forestowner. Look at your own land in relation toproperties around you and ask, “How am I influ-encing the wildlife?” For example, does a fenceon your property force deer onto your neighbor’sproperty, or vice-versa? Have you seen increasesin animal damage, or experienced more wildlife-human confrontations? Many changes in localwildlife populations are due to cumulative effectsover a larger area. Landowners can play a signifi-cant role in alleviating some of these.

Succession

It is impossible to talk about wildlife habitatwithout discussing plant communities andsuccessionthe gradual replacement of one plantcommunity with another over time. For example,vegetation changes occurring within a foreststand after a fire illustrate succession. Composi-tion and structure of the habitat change fromgrasses and forbs, to shrubs, to saplings, and thento mature forest; old growth occupies the final

stage (Fig. 1). As plant communities change fromone stage to the next, animal communities changeas well. Some animals, such as bobwhite quailand elk, require more than one successional stage.Other species, like marten and spotted owl, relyon only one stage of succession for survival.Because each stage of plant succession has ananimal community associated with it, an ex-tremely important concept in habitat managementfollows: Managing for one animal communitymay be detrimental to another. To encourage acertain animal or group of animals, you have tomanage succession.

Succession develops as a result of land man-agement practices or catastrophic disturbance,such as fire, wind, or flood. Natural disturbancestake place periodically in nature. Fires or flood-ing occur with relative frequency. Under naturalconditions, unmanaged stands of Ponderosa pinehave a parklike understory as periodic fires killoff younger, smaller trees. This cycle of distur-bance and recovery is natural for ponderosa pine.Plants and animals in these landscapes haveadapted to the conditions. Fire prevention alterssuccession in these stands, and prescribed fire orthinning becomes necessary to maintain a morenatural state.

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The Basics of Survival

Wildlife foods are generally described by theiravailability and palatability. Availability refers tothe season the food is present in the habitat, howmuch food there is, and how easily animals canaccess food. For example, an area that providesbrowse for deer in the spring and summer mayhave no value as a foraging area during thewinter. Yet an area that has the potential toprovide excellent winter range for elk may gounused because the browse is too difficult for elkto reach.

Palatability describes the nutritive and digest-ible qualities of food. Wildlife select and eatpalatable foods more often than other foods.

Different levels of wildlife foodpreferences arerecognized: 1)preferred foodshave high nutri-tional value andare eaten morefrequently; 2)moderate valuefoods, or staples,provide ad-equate nutritionbut are usuallythe animal’s

second choice; and 3) stuffing or emergencyfoods provide low nutritional value. Wildlife eatthese foods in large amounts only when nothingelse is available. Food preference relates directlyto nutritional quality.

Assessing food quality is an important issuewhen managing for herbivores, such as deer. Thequality of vegetation relates to the fertility of thesoil. The higher the soil fertility, the better thenutritional quality, or palatability, of the vegeta-tion. Many young plant shoots are extremelypalatable early in the growing season. Concernfor food quality does not pertain so much whenmanaging flesh eaters; meat protein is meatprotein, whether it comes from a mouse or amoose.

Producing healthy offspring is the most impor-tant factor in maintaining wildlife populations.Many species of North American wildlife onlymate during certain times of the year. Specieshaving a relatively small window of opportunityare under increased pressure to find a healthymate. Healthy mates are more successful atfinding food and defending a territory; they mayproduce more offspring, and are better able toprotect their offspring from predators. Healthyparents also will pass on those genes that makethem successful. This drive to reproduce healthyoffspring creates intense competition amonganimals for resources of food, water, and cover.

Carrying Capacity

The basic needs of wildlife are food, water,and cover. Elements too low in supply tosupport breeding and survival are considered“limiting factors.” Limiting factors deter-mine the numbers, types, and locations ofwildlife populations. Carrying capacityreflects the number of animals a habitatcan maintain in a healthy condition.Limiting factors of food, water, orcover determine this number.Identifying and controlling limit-ing factors is one way to managewildlife habitat.

Limiting Factors

Food

One way to categorize mammals is by thefoods they eat. For example, cougar, wolf, andfox are primarily meat eaters, or carnivores. Elkand deer are examples of herbivores; they eatplant material exclusively. Rabbits and rodentsare primarily herbivorous. Bears, though classi-fied as carnivores, are more omnivorous in termsof diet, eating a wide variety of both plant andanimal foods. Classifications are based, in part,on the types of teeth these animals have. Birdshave no true teeth, but they eat anything fromsmall mammals (raptors) to conifer needles(spruce grouse).

Table 1. Preferred foods of some Northwest wildlife species.

WHITE-TAILED and MULE DEERThimbleberry Snowberry New growth Douglas-fir Bitterbrush WillowMock orange Cherry Red stem ceanothus Ninebark Wild roseCurrant Serviceberry Western redcedar Snow brush SalalBuckbrush Elderberry Huckleberry Vine maple BlackberryChokecherry Raspberry Red-osier dogwood Deer brush AlfalfaClover * Balsamroot Bluebells Burnet HawkweedPrickly lettuce Dandelion Twinflower Trefoils Deer-fernDeer vetch Fireweed Pearly everlasting Vetch BulrushCat’s ear Swordfern Creeping Oregon grape Elk sedge MushroomsLichen Bluegrass Orchard grass Oats Wheat

ELKVine maple Salal Cascades mahonia Salmonberry WillowServiceberry Ceanothus Red-osier dogwood Chokecherry AspenBitterbrush Currant Cowparsnip Fireweed RoseSwordfern Trefoil Arrowleaf groundsel Clover * WildryeIdaho fescue Timothy * Yellow salsify Dandelion Elk sedgeBluegrass Needlegrass Orchard grass Rough fescue Redtop

Bluebunch wheatgrass

BLACK BEARDouglas-fir Lodgepole pine Engelmann spruce Silver fir BirchRed alder Subalpine fir Western hemlock Buffaloberry CherryCurrant Elderberry Western larch Devil’s club SnowberryServiceberry Salmonberry Western redcedar Huckleberry BearberryFescue Bluegrass Wheatgrass Brome FernsHorsetail Lichens Mosses Mushrooms AstersBiscuitroot Bluebells Cow parsnip Dandelion PhloxMustards Everlasting False Solomon’s seal Ants HoneyBeetles Bees Flies/wasps Rodents Fish

Elk calves Elk/deer (usually carrion) Deer fawns

UPLAND BIRDSAspen Alder Huckleberry Salal Clover *Blackberry Gooseberry Wild strawberry Chokecherry HazelnutCottonwood Buttercup Lupine Vetch Teasel *Wild carrot Wild rose Snowberry Hawthorn LegumesOaks Wild grape Native grass seeds Sumac AshKinnikinnik Elderberry Insects Bunchberry Cascara

Wildlife scientists who manage food resourcesfor wildlife want to provide high quality foods.They also are concerned with food quantity: isthere enough food to go around? The quantity ofavailable food often is the strongest limitingfactor in food resources. Encouraging naturalregeneration of native plant species is the best

way to improve food resources for wildlife.However, if these plants are naturally in shortsupply, then transplanting or propagating is thenext best thing. Table 1 lists native PacificNorthwest plant species which supply food formany species of wildlife.

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(continued on p. 5)

BIRDS OF PREY

Carrion Fish Small mammals Snakes Birds

Rodents Frogs Rabbits Grouse Insects

Waterfowl

COUGAR, LYNX and BOBCAT

Carrion (untainted) Rodents Deer Hares Rabbits

Elk calves Deer fawns Livestock (occasionally) Birds

WOLVES, COYOTE and FOX

Deer ** Caribou ** Rabbits and Hares Rodents Birds

Eggs Insects Any small mammal Fruits Nuts

(very opportunistic feeders)

MUSTELIDS

(skunk, weasel, marten, fisher and mink)

Insects Birds Any small mammal Carrion Porcupine ***

Eggs Fruits Rabbits Hares Amphibians

Crayfish

RODENTS

Fruits and Nuts Insects Vegetation Seeds Eggs

* nonnative species** Primarily wolves*** Fisher only

Water

Water is vital for wildlife survival. All animalsneed water to maintain healthy metabolic pro-cesses. Amphibians and waterfowl rely on waterfor basic life cycle processes, such as reproduc-tion and rearing young. Water must be availableall year round. Water comes in the form of rain,snow, or even dewdrops on leaves. Some ani-mals, especially in arid regions, meet their needfor water through the moisture in the foods theyeat.

Protect any natural source of water present onyour woodland, including ponds, catchmentbasins, natural springs and seeps. Leave debrisand trees that naturally fall into creeks, ponds,and streams because they help provide important

habitat for fish and amphibians. If debris makesthe water unavailable to wildlife, some debrisclearing may be necessary. Since many speciesof wildlife use watering areas, maintain nearbyvegetation to provide cover or escape frompredators.

Reliable water sources become more importantin dry climates. On rangelands, the easiest way toprovide water is by making a wildlife “guzzler,” arainwater-filled tank. Guzzlers were originallydesigned to provide water for ground birds, suchas grouse, and are sometimes referred to as“gallinaceous” guzzlers. For information onconstructing a wildlife guzzler, contact the habitatdevelopment specialist at your state Fish andWildlife office or the Natural Resource Conserva-tion Service.

(Table 1. cont.)

5

6

In forested areas where water is limiting,building a pond may be a good option. Siteconditions, such as soil type and aspect, willdictate the design and construction of a woodlandpond. Revegetation will be an important consid-eration. Water transports materials into and out ofecosystems. Use only native plants and notexotic species in pond revegetation. For moreinformation on pond construction, contact theDepartment of Ecology or your state Fish andWildlife office.

If you’ve decided to develop a watering areaon your property consider these points. First,choose the location for your watering area care-fully. Severe trampling and overgrazing ofriparian vegetation can increase the risk of soilcompaction and erosion. Place watering struc-tures where they will not be subjected to floodwaters or silt collection during spring runoff.Second, the addition of a water source may attracta disproportionate numbers of predators to thearea. Make sure enough vegetation is growingnearby for escape cover and protection frompredators. Unnatural increases in predation couldhave dramatic effects on prey populations.

Cover

Wildlife cover is any physical feature thatprovides an animal with shelter, protection orconcealment. Cover most often consists ofvegetation, but rocky outcrops, caves, and evenabandoned cabins also are useful to wildlife.Cover comprises three general types: 1) hiding orescape cover for use by animals who seek protec-tion from predators; 2) thermal cover, for protec-tion from elements such as wind, rain, and tem-perature extremes, and 3) reproductive cover, foruse by nesting animals such as birds and squir-rels.

Though all wildlife needs cover, some animalshave very specific cover requirements. Forexample, wild turkeys require roosting cover.Quail need cover for roosting, concealment andresting. A stand of coniferous trees, greater than40 feet in height, with a canopy coverage of more

than 70% provides good thermal cover for deerand elk. This configuration protects deer and elkfrom severe cold weather.

Not all cover is of equal value to all animals.Good hiding cover in the spring does not neces-sarily mean good thermal cover in the winter. Formany animals, cover requirements change withthe seasons.

If you wish to increase cover, you can makesmall-scale improvements fairly easily. Addhiding and escape cover for birds and smallermammals by leaving slash or brush piles. Use theby-products from other land managementpracticesa timber harvest or a thinningforbrush-pile construction. You also can placewoody debris along fence lines and encouragevegetation growth, thus forming more permanentstructures. Use existing fences to develophedgerows by planting woody, shrubby plantsalong the fence line. Hedgerows supply impor-tant hiding and nesting cover for small mammalsand birds. They also provide good food resourcesand can offer important migration paths for manywildlife species.

Cover improvements for larger mammals (deerand elk), may require long-term planning. Ad-equate hiding cover will hide 90% of a standingdeer or elk up to a distance of 200 feet. Tallwoody shrubs and short trees should provideenough cover to meet these requirements. Thevalue of cover for larger game animals alsodepends on the surrounding landscape features.Supplying a good foraging area may not beenough. Foraging areas for elk and deer shouldbe less than 600 feet from hiding cover. Elk anddeer are influenced by the larger habitat mosaicand respond to seasonal changes in food supplyby migrating. To improve habitat conditions forlarge animals, work across individual ownershipsif possible. Your land may have great thermalcover for elk and deer while your neighbors’ landmay provide excellent winter forage. Together,you can improve the health and well-being of thewildlife in your area.

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Structural Diversity

The structural diversity of the landscape affectswildlife populations because it dictates the avail-ability and accessibility of food, water, and cover.Structural diversity refers to the vertical andhorizontal features of the landscape. The layeringof canopy and understory vegetation within anindividual stand makes up the vertical plane.Different successional stages across the land-scape, such as agricultural lands adjacent to aforest, or a river and its floodplain, create thehorizontal features. These structural differencesinfluence both the movements and types ofwildlife populations living within forest ecosys-tems. The following sections identify basicstructural features and discuss their value forwildlife.

Snags and Cavity Trees

Providing snags and cavity trees is an effectiveway to increase habitat for wildlife. Snags arestanding dead trees, and cavity trees are standinglive trees that have natural internal cavities.Ideally, both structures should be at least 6 feettall and have a diameter at breast height (dbh) ofat least 4 inches. However, smaller stumps alsocan be useful as foraging and nesting habitat forsome bird species. Snags are categorized asbeing either hard or soft. Hard snags are com-posed of harder wood, generally branched andshowing no signs of decay. Soft snags showadvanced stages of decay, resulting in softerwood. We most often associate snags and cavitytrees with woodpeckers, chickadees, and birds of

Figure 2. From death to complete decomposition, snagsprovide habitat for wildlife.

prey. Many other species depend on snags duringsome stage of their life cycle. Snag users areeither primary or secondary cavity nesters. Pri-mary cavity nesters consist entirely of birds andinclude the woodpeckers, chickadees, and flick-ers. They actively excavate cavities. Whetherthey use hard or soft snags depends on the birdspecies in question (Table 2). Secondary cavitynestersa wider variety of wildlife speciesinclude mammals and some waterfowl. Theseanimals use both natural cavities and cavitiesexcavated by a primary excavator. It is notunusual to find both primary and secondarycavity nesters using the same snag at the sametime (though not in the same cavity).

Snags are places of great diversity because,like a forest, they also experience successionalchanges over time. Figure 2 shows the transitionof a snag from death to complete decomposition.As the snag decays, a different subset of thecommunity develops within each decay stage. Inother words, snags provide communities withincommunities.

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Table 2. Types of snags used by primary and secondary cavity nesters (From Thomas et al., 1979)

Species Snag Type Snag Sizeminimum nesting minimum

height (feet) dbh (inches)

Primary Cavity Nesters

Black-capped chickadee soft 6 4Mountain chickadee soft 6 4Chestnut-backed chickadee soft 6 4Downy woodpecker hard 15 6Hairy woodpecker hard 15 10Yellow-bellied sapsucker hard 15 10Pileated woodpecker hard 31 20Common flicker hard 6 12Red-breasted nuthatch soft 15 12

Secondary Cavity Nesters *

Black-capped chickadee - 6 4Mountain chickadee - 6 4Chestnut-backed chickadee - 6 4Tree swallow - 15 10Brown creeper ** - 15 10Red-breasted nuthatch - 15 12Common flicker - 6 12Mountain bluebird - 6 10American kestrel - 15 12Pygmy owl - 30 12Barred owl - 30 20Big brown bat ** - 15 12Common merganser - 6 20Wood duck - 6 20Marten - 15 15Fisher - 30 20Short-tailed weasel - 6 10

* Uses both natural cavities and those made by other species** May also use space underneath loose bark

Consider these points when planning for snagretention. First, larger diameter snags providemore room for nesting and raising young, offermore effective protection from predators, andprovide better insulation against severe weather.Second, planning for a mix of both soft and hardwoods will attract a variety of snag users in thearea. If this is not possible or desired, manage forwoodpeckers (hardwood), and over time all othercavity users will follow. Table 3 provides infor-mation regarding the numbers of snags needed forattracting woodpeckers at different populationlevels. Finally, retain snags within as many

different successional stages as are present onyour property. Some snag dependent speciesprefer cavity trees found within specific succes-sional stages. For example, pileated woodpeckersprefer hardwood snags in mature forests, whilebluebirds prefer previously excavated snags ingrass-forb or shrub-seedling stages.

Nest Boxes

Snag management takes preparation andplanning, and it may be some time before anyresults are realized. In the meantime, an effectivemethod for attracting cavity nesters might be the

Table 3. Snag Management for Woodpeckers (Primary Excavators) (From: Thomas et al. 1979)

Ponderosa Pine / Mixed Conifer Community

If Snag DBH is > 10 in2 If Snag DBH is > 20 in2

Potential population Number of snags Potential population Number of snags per 100 acres * per 100 acres *

20% 15 20% 340% 30 40% 560% 45 60% 880% 60 80% 11

100% 75 100% 14

Riparian (Cottonwood / Alder) Community

If Snag DBH is > 6 in2 If Snag DBH is > 12 in2

Potential population Number of snags Potential population Number of snagsper 100 acres * per 100 acres *

20% 30 20% 2040% 60 40% 4060% 90 60% 6080% 120 80% 80

100% 150 100% 101

* For areas less than 100 acres, number of snags/acres may be calculated proportionately.

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use of artificial nesting structures. Nest boxesand nesting platforms are a good temporaryoption, but they should never be used in place ofsnags. Natural snags and cavity trees supply foodresources as well as nesting habitat, and arepreferred by most cavity nesting species. How-ever, many species will use artificial structures.These structures are useful during reforestationperiods because they encourage cavity nestingowls and raptors. These birds serve as excellentcontrols of rodent populations during seedlingestablishment. If you use nest boxes, maintainthem in good condition. Clean out nest boxesbefore each consecutive nesting season or, overtime, they will become unusable. The size of thebox, shape of the entrance hole, and placement ofthe box in the environment varies for somespecies. Table 4 describes the nest box specifica-tions of some selected cavity nesting birds.

Large, organic debris (LOD)

Large, organic debris, also known as coarse,woody debris, is the dead woody material thataccumulates on the ground after windstorms,snowslides, timber harvest, and flooding. Al-though we realize LOD can be a fire hazard, werecognize the importance of this material to thefunctioning of forest ecosystems. As woodydebris slowly decays, it provides a suitablemedium for microorganisms and bacteria that aidin the decaying of woody material. As thismaterial is broken down, nutrients return to thesoil, where they become available to plants,which in turn provide food for animals.

LOD provides many resources to many ani-mals. Slash piles provide roosting cover for quailand wild turkey, and hiding cover for smallmammals. Downed logs offer protective passagefor amphibians, and serve as “drumming” logs for

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the courtship displays of ruffed grouse. Becausedecaying woody material houses many inverte-brates, it also provides forage for many speciesfrom porcupine to grizzly bear.

Edge

Edge is the area formed between two differentsuccessional stages, or plant communities, suchas a forest and a meadow. Edges typically areareas of highly diverse wildlife communities.

There are two kinds of edge: inherent edge andinduced edge. Inherent edge forms naturally dueto the differences in soils, climate, and topogra-phy across the landscape. Induced edge resultsfrom land-management practices such as cattlegrazing, fire, and timber harvest. Edge manage-ment involves the preservation of inherent edgeand the creation of induced edge. It is a powerfultool in the management of wildlife habitats.

Each successional stage, or plant community,has a wildlife community associated with it.Where stages meet, animal communities overlap.This area of overlap is called an ecotone, and thesubsequent mixing of wildlife communities iscalled the edge effect (Fig. 3). The ecotoneattracts species of wildlife such as elk, deer,moose, and some songbirds. These speciesrequire more than one habitat type to meet theirsurvival needs. Edges also attract many predatorsbecause they find large numbers of prey animalsin these habitats. The chance of attracting wild-life that use edges will increase with the amountof edge present on the landscape.

However, the amount of edge is not the onlyissue; how that edge is arranged across the land-scape also is important. Use edge carefully.Induced edge increases the numbers and diversityof wildlife species. However, too much edge mayhave adverse effects on animals that requirelarger, continuous blocks of forest for survival.Unfortunately, little research has been completedregarding the sizes of habitat blocks needed bybirds and other “edge-sensitive” species.

The creation of edges increases horizontaldiversity, which is the mix of successional stagesacross the landscape. The arrangement of differ-ent habitat types dictates the distribution of manywildlife species, especially those using more thanone successional stage, such as elk and deer, andprobably predators. Cougars may use earlysuccessional areas (i.e., edges and clearings) forhunting, yet they tend to bed down in matureforest stands where more resting cover is avail-able. The need for more than one kind of habitatmay be a necessity for many predators because itis also a necessity for prey.

Forest Fragmentation

The close relationship between wildlife and theenvironment calls for a wide variety of habitats.This goal can be achieved across ownerships.Properties of many sizes make up the nonindus-trial private forest lands in the Northwest. Land-owner management decisions directly affectneighboring lands and associated wildlife popula-tions. Some areas of conservation science havevoiced concern that forest fragmentation may beincreasing as forest lands are divided into smallerparcels.

The theory of forest fragmentation is based onobservations of wildlife populations living onislands. When the island is bigger, more speciesinhabit the island. Conversely, when the islanddecreases in size, so does the number of species.Some conservation biologists are concerned thatas forests become increasingly “islandlike”through natural disaster or extreme land-usepractices, the number of species may be shrink-ing. As forests become smaller and are separatedby greater distances, wildlife populations maysuffer. (Fig. 4a.)

Figure 3. Community C (area of increased diversity)results because of the overlap formed betweencommunities A and B. (From Thomas et al., 1979)

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Forest fragmentation restricts wildlife mobilityand impacts the health of local wildlife popula-tions. To maintain healthy populations, manyanimals must migrate away from the birthplace.This dispersal prevents breeding among relatedindividuals. Forest fragmentation may restrict themovements of animals and increase the risk ofinbreeding. Over time, this may result in theextinction of that local population. Fragmentedforests also may impact migrating animals bylimiting their access to food and water.

Several studies have focused on the harmfuleffects of forest fragmentation on songbirds.Some show a reduction in the number of nestingbirds in highly fragmented forests. The decline inbreeding songbirds is most noticeable in forestsof the eastern United States; however, the westernstates are beginning to show similar trends.Many impacted species seem to be sensitive toincreased amounts of induced edge and to result-ing environmental changes. Edges may attract a

disproportionate number of predators; or exoticplants and noxious weeds may become estab-lished and out compete native species. Changesin temperature and relative humidity within theforest stand may alter the vegetative composition.All of these changes can impact wildlife commu-nities. Maintaining larger “blocks” of habitatmay lessen the impact of ecological changes.Appropriate block size is still under debate andwill most likely be site and species specific.

Corridors

Until more information is available regardingthe effects of forest fragmentation, corridors canserve as forested “links” between two similarhabitat patches. Corridors may provide safetravel routes between habitat “islands,” reducingthe negative impacts of forest fragmentation onwildlife populations (Fig. 4b). Corridors providemore continuity to a landscape, and may helplandowners achieve their management goals,while providing for wildlife.

Figure 4a. Fragmentation in forestscreates small “islands” of habitat,which may limit resourceavailability to wildlife.

Figure 4b.Corridors may reducethe effects of fragmentation byproviding wildlife with vitallinks to resources.

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Riparian Habitat

Riparian zones are areas that surround watersources. They support high soil moisture andassociated moisture-loving vegetation. Theseareas of high biodiversity often provide thenecessary elements for survivalfood, water andcoverin the same location. Changes in soilmoisture characteristic of riparian zones promotemany different plant communities within a rela-tively small area. Diverse plant communitiessupport more species of wildlife (Fig. 5). Ripar-ian zones are also areas of edge, associated withincreased wildlife diversity.

The most important consideration in riparianzone management is avoiding stream bank ero-sion. Soil erosion occurs primarily because of

vegetation removal through livestock grazing,road building, or tree harvest. If vegetation isremoved, the resulting changes in water chemis-try and temperature may harm fish, aquaticinvertebrates, amphibians, and many songbirds.Riparian zones are integral parts of entire water-sheds. Removal of riparian vegetation impactswater quality downstream and throughout thewatershed. Riparian areas may be extremelysensitive to disturbance. Changing riparianhabitat impacts a higher proportion of wildlifethan is indicated by the amount of area disturbed.Thus, maintaining riparian vegetation communi-ties becomes extremely important in riparianmanagement.

Figure 5. Due to changes in soil moisture, riparianzones support many different plant communities in arelatively small area.

References

Wildlife Habitats in Managed Forests: the Blue Moun-tains of Oregon and Washington. 1979. Ag.Handbook No. 553 J.W. Thomas, Ed. USDA,Forest Service, Pacific NW Region, Portland, OR.

Patton, D.R. 1992. Wildlife Habitat Relationships inForested Ecosystems. Timber Press, Portland,OR.

Robinson, W.L., and E.G. Bolen. 1989. Wildlife Ecol-ogy and Management. 2nd edition. MacmillanPublishing Company, New York, NY.

Research and Management Techniques for WildlifeHabitats. 1994. T.A. Bookhout, Ed. The Wild-life Society, Allen Press, Inc. Lawrence, KS.

Watson, K., and M. Schirato. Managing Deer on SmallWoodlands. Woodland Fish and Wildlife Publi-cation. World Forestry Center, Portland OR.MISC 0189.

Edge, W.D. Managing Small Woodlands for Elk.Woodland Fish and Wildlife Publication. WorldForestry Center, Portland OR. MISC 0164

Hanley, D.P., and D.M. Baumgartner. Terminology forForest Landowners. EB1353. WSU Coopera-tive Extension. Pullman, WA.

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Conclusion

Resource Publications

• A Private Landowner’s Guide to Managing BlackBear Habitat. BULL 777. University of IdahoExtension. Moscow, ID.

• Is There a Place For Fish and Wildlife in YourWoodland? Woodland Fish and Wildlife Publi-cation. World Forestry Center, Portland OR.MISC 0132.

• Riparian Areas: Fish and Wildlife Havens.Woodland Fish and Wildlife Publication. WorldForestry Center, Portland OR. MISC 0133.

• Managing Small Woodlands for Ruffed Grouse.Woodland Fish and Wildlife Publication. WorldForestry Center, Portland OR. MISC 0141.

• Managing Small Woodlands for Cavity NestingBirds. Woodland Fish and Wildlife Publication.World Forestry Center, Portland OR. MISC 0160.

Wildlife managers can support wildlife bymanaging the habitat. This publication hasfocused on managing wildlife communities, not asingle species. The community managementapproach may not be possible given environmen-tal limitations, or landowner choice. The ques-tions that you as a landowner must ask yourselfare, “What does my land provide for wildliferight now?” and “What do I want my land toprovide in the future?” Identify how the wildlifeuse the land before implementing any manage-ment activity. Take an inventory, determine sitelimitations, then define specific objectives.Always keep a landscape perspective. Wildlifemanagement across ownerships may be difficult,but not impossible. You and your neighbor mayhave similar goals regarding wildlife. Working

together can offer good opportunities for formingeffective and ecologically sound managementstrategies.

Wildlife means different things to differentpeople. Whatever values you place on wildlife,the importance of sustaining good quality habitatnever varies. Owners of forestlands take on thespecial responsibility as stewards of that land.Wildlife does not recognize differences in owner-ships or property lines. Rather, wild animalsrecognize areas where they can get food andwater, or hide from predators, or safely raise theiryoung. It is up to us to understand the needs ofwildlife, and the ways in which we impact wild-life populations, if we are to share the world withthem.

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Glossary

ASPECT: The compass direction which a slope faces.

BIOLOGICAL DIVERSITY: Richness and abundance of species, and variety of natural communities inany environment. Both the number of species and the number of individuals of each species areimportant in considering the extent of biological diversity in an area. Also referred to as biodiversity.

BRUSH: Commonly refers to shrubs and small trees; sometimes undesirable.

CARNIVORE: A meat-eating animal and, rarely, a plant, (examples are cougars and pitcher plants).

CARRYING CAPACITY: The number of animals a habitat can maintain in a healthy condition.

CAVITY TREES: Standing live trees which have natural internal cavities.

COMMUNITY: A natural assemblage of different organisms living and functioning together in a particulararea, with some degree of influence on each other. Usually named for the dominant plants, animals,or major physical components of the area.

CONSERVATION SCIENCE: The science of diversity, scarcity, and survival of species. Deals with activemanagement to protect and maintain genetic variety within species. Deals also with the concept ofsustainability and relationships between living and nonliving resources.

CORRIDORS: Generally linear strips of habitat linking isolated patches of natural habitat in the landscape.

COVER: Vegetation or other natural shelter serving to conceal wildlife from predators. Also refers to theprotective shade vegetation provides to wildlife, fish, and the forest floor.

DISTURBANCE: A natural or human-caused event, such as a forest fire, disruptive wind storm, or insectinfestation, that alters the structure and composition of an ecosystem.

ECOLOGY: The science that studies the interaction of plants and animals with their environment.

ECOSYSTEM: Ecological system. An interacting system of living organisms and their environment. Thedynamic relationships of living and nonliving components of a region, as well as the forces, such asweather and wildfire, that affect them.

ECOTONE: A transitional area between two vegetation communities containing the characteristic speciesof each as well as characteristics of its own. A point of abrupt change, such as a prairie-forestjunction or a land-water interface.

EDGE: The contact zone between two different types of habitat. There are two kinds of edge: inherentwhich is natural edge due to differences in soils, climate, topography; and inducedwhich is theresult of human practices such as grazing, road building, and timber harvest.

EDGE EFFECT: The tendency toward greater species variety and greater density of animal and plant life inthe margin where two different vegetative communities meet. (See also Ecotone)

EDGE SENSITIVE: Any animal or plant species which is negatively impacted by induced edge. Speciestend to be extremely sensitive to alterations in the local environment, such as changes in climate andvegetative composition, and increases in predator populations.

ENVIRONMENT: The external conditions, both physical and biological, in which an organism lives.Includes climate, soil, topography, food supply, and all other influences affecting development.

FRAGMENTATION: The breaking up of a large forest area into patches either by natural processes orthrough management or conversion to other land uses. Natural habitats may become separated intoisolated segments or “islands.”

GAME ANIMALS: Animals traditionally hunted for sport and used as a resource, (examples are elk,grouse, and ducks).

HABITAT: The local environment in which a plant or animal naturally lives and develops.

HABITAT MOSAIC: The physical layout of habitat types over a large area. (See also Landscape)

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HABITAT TYPE: Classification of a land area according to dominant plant forms (usually trees and shrubs)and physical characteristics. Can help to indicate the biological potential of a site.

HERBIVORE: A plant-eating animal, (examples are deer and rabbits).

LANDSCAPE: A large land area composed of interacting groups of ecosystems, including all the physicaland biological aspects of such an area regardless of ownership.

LANDSCAPE ECOLOGY: The study of biological interactions across a large land area, or watershed.

LIMITING FACTORS: Environmental factors that far outweigh other factors in restricting normal increaseof a species.

NONGAME: Animals not typically hunted for sport or used as a resource, (examples are songbirds, am-phibians).

NUTRIENT CYCLING: The biological, geological, and chemical circulation of inorganic elements such asnitrogen, phosphorus, and potassium through the soil, living organisms, water, and air, thus providingnutrients to animals and vegetation in the process.

OMNIVORE : An animal that regularly eats both plant and animal foods.

ORGANIC DEBRIS: Material produced by plants and animals, such as leaves, branches, logs, bones, hair,etc.

PALATABILITY: The degree to which something tastes good; the better something tastes, the greater thepalatability.

POPULATION: Organisms (trees, shrubs, herbs, animals, insects, etc.) of common ancestry that occupy aparticular area.

RIPARIAN : Pertaining to the area along the banks of a river, stream, or lake.

SHRUB: A low-growing perennial plant with a woody stem and low branching habit.

SILVICULTURE: The art, science, and practice of establishing, tending, and reproducing forest stands withdesired characteristics, based on knowledge of species characteristics and environmental require-ments.

SLASH: Nonmerchantable residue left on the ground after logging, thinning, or other forest operations.Includes tree tops, broken branches, uprooted stumps, defective logs, and bark. Slash has certainecological benefits, such as adding nutrients to the soil or providing wildlife habitat.

SLOPE: The incline of the terrain usually expressed as the amount of incline in feet over a hundred feet ofhorizontal distance.

SNAG: The upright trunk of a dead or dying tree.

SOIL COMPACTION: The process by which soil particles are squeezed or compressed, reducing air andwater spaces.

SPECIES: A group of organisms (plants or animals) that are very similar genetically and can interbreedfreely with each other but not with other groups.

SPECIES COMPOSITION: The mixture of plant and animal species found in a defined area.

STAND: A recognizable area of the forest that is relatively homogeneous and can be managed as a singleunit.

STRUCTURAL DIVERSITY: Refers to the horizontal and vertical features of an area.

SUCCESSION: The predictable changes in the kinds and numbers of plants and animals that will inhabit agiven place over a long period of time.

UNDERSTORY: That portion of the trees or other vegetation below the canopy in a forest stand.

WETLANDS: Marshes, swamps, and other water-saturated soils. These areas offer important habitat forwildlife, significant support of nutrient cycling in ecosystems, and protection against the severity ofstorms and floods. Wetlands are among the lands most vulnerable to destruction and conversion toother uses.

Janean H. Creighton, M.S., Wildlife, Extension Coordinator, and David M. Baumgartner, Ph.D., Extension Forester, Departmentof Natural Resource Sciences, Washington State University, Pullman.

College of Agriculture and Home Economics

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Alternate formats of our educational materials are available upon request for persons with disabilities. Please contact theInformation Department, College of Agriculture and Home Economics, Washington State University for more information.

Issued by Washington State University Cooperative Extension and the U.S. Department of Agriculture in furtherance of the Actsof May 8 and June 30, 1914. Cooperative Extension programs and policies are consistent with federal and state laws andregulations on nondiscrimination regarding race, color, gender, national origin, religion, age, disability, and sexual orientation.Evidence of noncompliance may be reported through your local Cooperative Extension office. Trade names have been used tosimplify information; no endorsement is intended. Published November 1997. Subject code 400. B. EB1866.