APEX

Alaska

Predator

Ecosystem Experiment

Rob SuryanPat Jodice

David Irons Dan Roby Evelyn Brown

Site-specific Factors Affecting Productivity Of An Upper Trophic Level Marine Predator:

Bottom-up, Top-down, And Mismatch EffectsOn Reproduction In A Colonial Seabird

Breeding Success & Prey Abundance

Total prey abundance(m2/km2)

0 10 20 30 40 50 60

fledg

lings

/ ne

st

0.0

0.2

0.4

0.6

0.8SB95 SB96

SB97SB98

SB99

EI95EI96

EI97

EI98EI99

NI96

NI97

NI98

NI99

SI95

Alaska

Prince William Sound

Reasons for Study

Regime Shift in the Gulf of Alaska

Exxon ValdezOil Spill

Anderson and Piatt. 1999. Mar. Ecol. Progr. Ser. 189:117-123

Black-legged Kittiwakes

Egg Chick Fledgling24 days 37 days

Chick Provisioning = 2 to 4+ meals/day

Adult Foraging Range = 5 to 60 km(Range < 1 to > 100km)

(1-3) (1-3)

Shoup Bay

N. Icy Bay

Eleanor I.

Seal I.

Gulf of Alaska

Prince William Sound

Study Areas

.

Eleanor & Seal Isles.~500 pairs

Shoup Bay~7,000 pairs

N. Icy Bay~1,800 pairs

Reproductive Success & Diets

Energy Density of Forage Fishes

myc

t.

herr

ing

sala

cape

lin

gunn

el

prkl

bck.

scul

pin

pollo

ck

Ene

rgy

dens

ity (k

J / g

wet

mas

s)

0

1

2

3

4

5

6

7

8

9lipid AFLDM

Energy Density of YOY < 1+-yr-old

1+-yr-old

Kittiwake Diet and Growth –Experimental Feeding

Days14 16 18 20 22 24 26 28 30

Bod

y M

ass

(g)

100

150

200

250

300

350

400

Diet = Pacific Herring

Diet = Walleye Pollock

Kitt

iwak

e

Romano et al.

Monitoring Foraging Activities

TransmitterAttachment

Data LoggerAt Colony

Tracking by Boat

Foraging Trips

% m

ass

0

20

40

60

80

100

Herring Sand lance Capelin Other

79 293 268 224 121 26 67 129 22 18 70 60

nosurv

a)

nodata

nosurv

Diets

Preferential Selection of Prey Type

Herring Sand lance

Selection Similar to Availability (P > 0.05)

Significant Positive or Negative Selection (P < 0.05)

Bi

% o

f oto

liths

0

20

40

60

80

100

'95 '96 '97 '98 '99 '95* '96 '97 '98 '99 '95 '96 '97 '98 '99

YOY 1-yr-old 1+ & 2-yr-old

Shoup Bay Eleanor Island N. Icy Bay

0

35 56 42 89 43 5 7 36 7 14 34b)

nosurv

nodata

nosurv

Age Classes of Forage Fish in Kittiwake Diets

96 % of Sand lance were YOY

Herring

% AGE ONE HERRING IN DIET0 20 40 60 80 100

0

20

40

60

80

100

INDEX OF PREY ABUNDANCE (SCHOOLS/KM)0.0 0.2 0.4 0.6 0.8

30405060708090

100

% YOY HERRING AND YOY SAND LANCE IN DIET0 20 40 60 80 100

% F

EE

DIN

G O

CC

UR

ING

IN F

EE

DIN

G F

LOC

KS

0

20

40

60

80

100

a

b

c

r2 = 0.2796P = 0.1778

r2 = 0.7395P = 0.0007

r2 = 0.7881P = 0.0003

Prey Type and Feeding Flock Use

Feeding Frequency vs. Productivity

Energy provisioning rate (kJ nest-1 day-1)100 200 300 400 500 600 700

0.0

0.2

0.4

0.6

0.8BA

BA

BACH CH

ELEL

EL

EL

GUGU

GU

GU

IC

IC

ICSH SH

SHSH

SH

R2= 0.48

Pro

duct

ivity

(fled

glin

gs /

nest

)

meal delivery rate * meal size * energy density

Jodice et al. 2000

Forage Fish Sampling

Clupea pallasi Ammodytes hexapterus

Forage Fish Abundance(surface area density [m2/km2])

Surfa

ce a

rea

dens

ity (m

2 /km

2 )

0

10

20

30

40

50

60

'95 '96 '97 '98 '99Shoup Bay Eleanor Island N. Icy Bay

'95* '96 '97 '98 '99 '95 '96 '97 '98 '99

nodata

Location

North Central South

Phyt

opla

nkto

n ab

unda

nce

(ml /

m2 )

0

2

4

6

8

10

12

1994 1995 1996 1997 1998 1999

Phytoplankton Abundance

Data courtesy of Prince William Sound Aquaculture Corporation

020406080

100

YOY

1 yr old

1+ and 2 yr old

1989 1990 1995 1996 1997 1998-0.2

-0.1

0

0.1

0.2

0.3

Shoup Bay

00.20.40.60.8

1

Hydroacoustic Data - Juvenile HerringBiomass Density

Kittiwake Diets - Ages of Herring Consumed

Kittiwake Reproductive Success(relative to 6-yr mean)

A

B

C

Forage Fish Distribution

Brown and Moreland 2000

Response to Weekly Fluctuations in Prey Abundance

1 2 3 4 5

Dur

atio

n (h

rs) &

No.

0

2

4

6

8

1 2 3 4 5

Trip duration No. of trips per day

Herring

Sand lance

% O

ccur

renc

e

0

20

40

60

80

100m

2 /km

2

0

5

10

406080

100

0

5

10

15

20

Week of chick-rearing

1 2 3 4 5 1 2 3 4 5

15 31 66

39 66 5163 85

56

3357

3740 12 19 28 34

26

16 16

14 11 2025

22

20 16 28 3229 23 17

2231 34

31 28

a b c

d e f g

h ji k

1997 1998 19991996

Age-1 YOY Age-1 YOYHerring:

G ro w th

Age (d ays)0 5 10 15 20 25 30 35

g

0

100

200

300

400

500

1999199819971996

0 1 2 3 4 5Dur

atio

n (h

rs) &

No.

02468

W e e k o f c h ic k -re a r in g

0 1 2 3 4 5 0 1 2 3 4 5 0 1 2 3 4 5

% O

ccur

renc

e

02 04 06 08 0

1 0 0

T r ip d u ra t io n N o . o f tr ip s p e r d a y

H e rr in g S a n d la n c e1996 1997 1998 1999

Age-1 YOY Age-1 YOY

(YOY)

Chick Survival and Growth

Bet

a su

rviv

al

0.00

0.25

0.50

0.75

1.00

Chi

ck g

row

th (g

/d)

12

13

14

15

16

17

18

Nea

r-fle

dgin

g m

ass (

g)

360

370

380

390

400

410

420

a

b

c

'95 '96 '97 '98 '99Shoup Bay Eleanor Island N. Icy Bay

'95* '96 '97 '98 '99 '95 '96 '97 '98 '99

40

25 3633

19

nosurv

14

2726

15

13 26 25

70 94

73

6787

3463

67

31

nodata

nohatch

2353

47

1634

44

2951

45

26

2812 24

nodata

nodata

nosurv

nohatch

nohatch

nodata

nosurv

nosurv

Beta ChickSurvival

Chick Growth

FledgingMass

Bet

a su

rviv

al

0.00

0.25

0.50

0.75

1.00

Chi

ck g

row

th (g

/d)

12

13

14

15

16

17

18

Nea

r-fle

dgin

g m

ass (

g)

360

370

380

390

400

410

420

a

b

c

'95 '96 '97 '98 '99Shoup Bay Eleanor Island N. Icy Bay

'95*'96 '97 '98 '99 '95 '96 '97 '98 '99

40

25 3633

19

nosurv

14

2726

15

13 26 25

70 94

73

6787

3463

67

31

nodata

nohatch

2353

47

1634

44

2951

45

26

2812 24

nodata

nodata

nosurv

nohatch

nohatch

nodata

nosurv

nosurv

Beta ChickSurvival

Chick Growth

FledgingMass

Surfa

ce a

rea

dens

ity (m

2 /km

2 )

0

1 0

2 0

3 0

4 0

5 0

6 0

'9 5 '9 6 '9 7 '9 8 '9 9S h o u p B a y E le a n o r I s la n d N . I c y B a y

'9 5 * '9 6 '9 7 '9 8 '9 9 '9 5 '9 6 '9 7 '9 8 '9 9

n od a ta

Forage Fish Abundance

Foraging Trip DurationChick-rearing

Dur

atio

0

1

2

3

4

5

6

7

'95 '96 '97 '98 '99 '95 '96 '97 '98 '99 '95 '96 '97 '98 '99

b

Shoup Bay Eleanor Island No. Icy Bay

1716

2532

34

716

16

11

9

19 12

nodata

nosurv

nosurv

Dur

atio

n (h

rs)

Kittiwake Productivity

Eleanor Island Icy BayShoup Bay

'95 '96 '97 '98 '99 '95 '96 '97 '98 '99 '96 '97 '98 '99

Pro

duct

ivity

(c

hick

s fle

dged

/ ne

st s

truct

ure)

0.00

0.25

0.50

0.75

1.00

Factors Affecting Chick Growth and Provisioning Rate

Foraging trip duration (hrs)2 3 4 5 6

Nes

tling

gro

wth

(g/d

)

13

14

15

16

17

18

Log 1-yr-old herring abundance index(m2/km2)

-1 0 1 2For

agin

g tr

ip d

urat

ion

(hrs

)

2

3

4

5

6

SBSB

SBSB

SB

EIEI

EI NI

NI NI

r2 = 0.57, F = 14.04, P = 0.003

Feeding rate is very important Effect of prey abundance varies with colony & prey type

Top Down EffectsEgg and Nest Predators:

Primary: Bald Eagle, Common Raven, Peregrine Falcon Opportunists: Glaucous-winged Gulls, Northwestern Crow,

Black-billed Magpie

Top Down Effects

Predation Rate and Predator Swamping:Example of intensity: 2 hr period = 36 eggs taken at Shoup Bayand 14 eggs taken at N. Icy Bay. Falcons observed taking up to6 chicks per day.

At 3 chicks per day 1 falcon pair could remove > 50% of chicks at Eleanor Island, but only 10% of chicks at N. Icy Bay and 3% at Shoup Bay.

Multiple Linear Regression Analysis

Independent VariablesLaying & Incubation Nestling

Lower Trophic Level Processes

Phytoplankton abundance X

Phytoplankton abundance in year t-1* X

Timing of peak phytoplankton abund. X

Spring SST (March to May) X

SST May X

SST June X

Total prey abundance X

Herring abundance X

Sand lance abundance X X

Capelin abundance X

1-yr-old herring abundance index* X X

1-yr-old herring and sand lance abundance index*

X X

Independent VariablesLaying & Incubation Nestling

Prey Abundance

Independent VariablesLaying & Incubation Nestling

Colony Effect, Prey Consumptionand Foraging Effort

Colony size X X

% mass of herring X

% mass of sand lance X

% mass of capelin X

% mass of 1-yr-old herring X

Age class of herring X

Foraging trip duration X X

Dependent Variables

Fledging success

(% of chicks fledged)

Mean clutch size

Laying success(% of nests with > 1

egg)

Egg laying

Near-fledging mass

Beta chick survival

Hatching success

(% of eggs hatched)

Nestling growthMedian hatch date

NestlingIncubation

Ind. Variable Coeff Std. Error t value Pr(>|t|) (Intercept) -60.1906 27.9667 -2.1522 0.0977

Year 0.0422 0.0140 3.0054 0.0397Size 0.0004 0.0000 8.5458 0.0010Dur -1.9430 0.0691 -28.1085 0.0000

lPr1yrHerr -5.7378 0.1994 -28.7791 0.0000Size:lPr1yrHerr 0.0001 0.0000 6.5023 0.0029

Size:Dur -0.0001 0.0000 -14.7983 0.0001lPr1yrHerr:Dur 1.4904 0.0542 27.5194 0.0000

MLR ResultsNestling Growth = Dependent Variable

Functional Response Curves(Cairns 1987)

Breeding Success vs. Prey Abundance

1-yr-old herring abundance(m2/km2)

0 2 4 6 8 100.0

0.2

0.4

0.6

0.8

a)

b)

Total prey abundance(m2/km2)

0 10 20 30 40 50 60

Bre

edin

g su

cces

s(fl

eglin

gs/n

est)

0.0

0.2

0.4

0.6

0.8

Seal Island

Shoup Bay

Eleanor Island

N. Icy Bay

y = 0.01 + 0.70(1 - e-0.81x)r2 = 0.39

1-yr-old herring abundance(m2/km2)

0 5 10 15 20 25

Nes

tling

gro

wth

(g/d

ay)

13

14

15

16

17

18

Seal Island

Shoup Bay

Eleanor Island

N. Icy Bayy = 14.50 + 2.36(1 - e-0.39x)r2 = 0.24

Growth vs. Age-1 Herring Abundance

Relationship is independent of direct top-down effects

ConclusionsBottom-up & Colony Specific Effects

Geographic distribution and abundanceAge classEnergy density (kJ/g)*

Important characteristics of Kittiwake Prey

Feeding frequency (trip duration)Energy density of prey

Important factors affecting Chick Survival and Growth

Shoup Bay: 1-yr-old herring critical for maximum productivityN. Icy Bay and Eleanor Island: can maintain high feeding

frequency with YOY fish

Colony-specific Kittiwake-Prey Relationships

Prey AbundanceAge-class of prey (capture time, feeding flock use)

Important factors affecting Foraging Trip Duration

ConclusionsTiming Mismatch and Top-Down Effects

Age 1 fish available early in breeding seasonYOY sand lance available early but availability limited

Forage Fishes – timing of arrival and peak abundanceEarly Season

YOY HerringYOY sand lance more available

Late Season

Predators that specialize on kittiwake coloniesReduced availability of alternative preyPredator swamping at large colonies

Top-Down Control

Kittiwakes

FundingExxon Valdez Oil Spill Trustee Council U.S. Fish and Wildlife Service

Special thanks toJeb Benson, Max Kaufman, Teresa Sauer

Aerial SurveysTim Veenstra (pilot) & Stephanie Moreland (observer)

Prey I.D.Kathy Turco & Greg Golet

Field CrewsJill Anthony, Matt Becker, Brenda Bilotta, Jared

Gerstein, James Hall, Bill Henry, Stephanie Holzwarth, Amy Kaplan, Laura Kennedy, Jonel Kiesau, Christopher Kuntzch, Kurt Lenington, Casey Lott, Chris May, Kristen Mosher, Laura Minich, Tim Meehan, Eva-Marie Muecke, Kyle Payton, Kim Raum-Suryan, Cynthia Restrepo, Janet Rothermel, John Ryder, Ruth Smith, Greg Spencer, Caroline Van Hemert, Tansy Wagner, James Weldy, Sean Wolfe

Acknowledgments