OCS Study MMS 2005-060 

FINAL REPORT 

Breeding Biology of King Eiders on the Coastal Plain of 

Northern Alaska 

Principal Investigator: Abby N. Powell 

 Research Associate Professor, Wildlife Biology 

 Institute of Arctic Biology 

 University of Alaska Fairbanks 

 and Research Wildlife Biologist, USGS 

 Alaska Cooperative Fish and Wildlife Research Unit 

Co-principal Investigator: Robert Suydam 

 Wildlife Biologist 

 North Slope Borough, Barrow, AK 

 

Co-principal Investigator: Rebecca L. McGuire 

 Graduate Research Assistant 

 Department of Biology and Wildlife 

 University of Alaska Fairbanks 

Prepared by: Rebecca L. McGuire 

December 2005 
Contact information 

e-mail: carter@sfos.uaf.edu 

 phone: 907.474.1811 

 fax: 907.474.1188 

 postal: Coastal Marine Institute 

 School of Fisheries and Ocean Sciences 

 P.O. Box 757220 

 University of Alaska Fairbanks 

 Fairbanks, AK 99775-7220 

2
Table of Contents 

List of Tables .................................................................................................................................. 4 

List of Figures................................................................................................................................. 5 

Abstract........................................................................................................................................... 7 

Introduction..................................................................................................................................... 8 

Objectives ................................................................................................................................... 8 

Methods........................................................................................................................................... 9 

Study areas.................................................................................................................................. 9 

Field methods.............................................................................................................................. 9 

Data Analysis................................................................................................................................ 11 

Habitat Use ............................................................................................................................... 11 

Nest Site Selection.................................................................................................................... 11 

Nest survival ............................................................................................................................. 11 

Brood rearing ............................................................................................................................ 12 

Results........................................................................................................................................... 13 

Habitat Use ............................................................................................................................... 13 

Nest Site Selection.................................................................................................................... 13 

Nest success .............................................................................................................................. 14 

Brood rearing ............................................................................................................................ 15 

Discussion..................................................................................................................................... 16 

Timing....................................................................................................................................... 16 

Habitat Use ............................................................................................................................... 16 

Nest site selection and nest success .......................................................................................... 16 

Summary....................................................................................................................................... 18 

Acknowledgements....................................................................................................................... 19 

Study products .............................................................................................................................. 20 

Literature Cited ............................................................................................................................. 21 

Appendix....................................................................................................................................... 23 

Figures........................................................................................................................................... 24 

 

3
List of Tables 

Table 1. General linear models of nest site selection by King Eiders nesting at Teshekpuk, Alaska, in 

2003, with corresponding AICc, ΔAICc, number of parameters (K), model weight (wi), and 

coefficient of determination (r

2

). ................................................................................. .........30 

Table 2. Model-averaged parameter estimates (θ), standard errors, and 95% confidence intervals 

derived from the 95% confidence set of candidate models from the logistic regression 

analysis of King Eider nest sites and random unoccupied sites at Teshekpuk, Alaska, 2003. 

See Table 5 for parameter definitions ...........................................................................................31 

Table 3. Factor loadings and eigenvalues from principal components analysis (PCA) of the variables 

distance to water, and the percentage of the following vegetation groups within 1 m of the 

nest or random location: carex, eriophorum, salix, dryas, cassiope, moss, ledum and lichen, 

Teshekpuk 2003. ....................................... .............................................................. ......32 

Table 4. General linear models of nest site selection by King Eiders at the 1m scale, with 

corresponding AICc, ΔAICc, , number of parameters (K), model weight (wi), and coefficient 

of determination (r

2

), Teshekpuk, Alaska, 2003.... .......................................................................33 

Table 5. Model-averaged parameter estimates (θ), standard errors, and 95% confidence intervals 

derived from the 99% confidence set of candidate models from the logistic regression 

analysis of King Eider nest sites and random unoccupied sites at the 1 m scale at Teshekpuk, 

Alaska, 2003. See Table 7 for parameter definitions ....................................................................34 

Table 6. General linear models of nest site selection by King Eiders nesting at Kuparuk, Alaska, in 

2003, with corresponding AICc, ΔAICc, number of parameters (K), model weight (wi), and 

coefficient of determination (r

2

)....................................................................................................35 

Table 7. Model-averaged parameter estimates (θ), standard errors, and 95% confidence intervals 

derived from the 92% confidence set of candidate models from the logistic regression 

analysis of King Eider nest sites and random unoccupied sites at Kuparuk, Alaska, 2003. 

See Table 9 for parameter definitions.................................... ...........................................36 

Table 8. Factor loadings and eigenvalues from principal components analysis (PCA) of the variables 

distance to water, and the percentage of the following vegetation groups within 1 m of the 

nest or random location: carex, eriophorum, salix, dryas, cassiope, moss, ledum and lichen, 

Kuparuk 2003. ...................................................................................................................37 

Table 9. General linear models of nest site selection by King Eiders at the 1m scale, with 

corresponding AICc, ΔAICc, , number of parameters (K), model weight (wi), and coefficient 

of determination (r

2

), Kuparuk, Alaska, 2003....................................................................... ....38 

Table 10. Model-averaged parameter estimates (θ), standard errors, and 95% confidence intervals 

derived from the 99% confidence set of candidate models from the logistic regression 

analysis of King Eider nest sites and random unoccupied sites at the 1m scale at Kuparuk, 

Alaska, 2003. See Table 8 for parameter definitions.. ..................................................................39 

Table 11. Summary of model selection results for the nest survival of King Eiders at two sites on the 

North Slope of Alaska, Teshekpuk and Kuparuk, in 2002 and 2003......................................40 

 Table 12. Estimates of nest survival over a 27-day interval (23-day incubation + 4 day average laying 

period) from the best approximating model (Ssite+island) for King Eiders at Teshekpuk and 

Kuparuk, in 2002 and 2003....................................... ............................................... ......40 

4
List of Figures 

Figure 1. Teshekpuk and Kuparuk study areas on the coastal plain of northern Alaska. King Eider nest 

locations in 2002 are indicated....................................................................... ................24 

Figure 2. The change in sex ratios of King Eiders observed at Teshekpuk Lake in June and July 2002 

and 2003........................................................................................................................................25 

Figure 3. Initiation of egg-laying for King Eider females at Teshekpuk and Kuparuk, Alaska, 2003..........26 

Figure 4. Age of King Eider nests when found in 2003 at Kuparuk and Teshekpuk, Alaska.......................27 

Figure 5. Percent of vegetation types within the entire study area and within 30 m of King Eider nests 

at Teshekpuk, Alaska, 2002. .........................................................................................................28 

Figure 6. Daily nest survival with a linear trend throughout the season for Teshekpuk ΒT(Teshekpuk) =

0.02 (1SE= 0.02, 95% CL = -0.03, 0.06) and Kuparuk ΒT(Kuparuk)= -0.02 (1SE= 0.02, 95% 

CL = -0.06, 0.02) for nests on islands (Ssite*T+island). ......................................................................29 

5
6
Abstract 

Little is known about the breeding biology of King Eiders (Somateria spectabilis), partly because 

they typically nest in remote areas, in low densities. The western North American population of King 

Eiders declined by more than 50% between 1976 and 1996 for unknown reasons (Suydam et al. 2000). 

Additionally, the National Petroleum Reserve-Alaska (NPR-A) is being leased for oil and gas exploration 

and may potentially be developed. The highest known density of nesting King Eiders on the north slope 

of Alaska is within the northeast planning areas of NPR-A (Larned et al. 2003). During the summers of 

2002 and 2003, we studied King Eiders in an area to the southeast of Teshekpuk Lake within the NPR-A, 

and in the Kuparuk oilfields on the North Slope of Alaska to provide information on their basic breeding 

biology and habitat use. We compared timing of nesting, nest success, and habitat use between a 

relatively undisturbed site at Teshekpuk Lake and the active Kuparuk oilfield. 

We found and monitored 39 to 44 active nests each year at each site. King Eiders at both sites 

selected nests in moist habitats, relatively close to water. Often these nests occurred on islands in tundra 

thaw lakes. Eiders also experienced higher nest success on these islands, probably due to decreased 

mammalian predation pressure. We determined that nest success was very low at both sites; this is not 

surprising for a long-lived, large-bodied species, and is not a cause for concern in itself. Brood survival 

was also low and females with broods left the breeding areas fairly soon after hatch. However, our sample 

size for brood survival was low. This study provided critical baseline data on nest success and habitat 

associations of King Eiders nesting on Alaska’s North Slope. 

7
Introduction

King Eiders (Somateria spectabilis) are one 

of the most northerly nesting ducks; seldom 

nesting below 65° N latitude (Lamothe 1973). 

Little is known about the breeding biology of 

King Eiders in either disturbed or undisturbed 

areas, partly because they typically nest in 

remote areas, at low densities. To date, there 

have been few studies dedicated to the breeding 

biology of King Eiders (Lamothe 1973, Cotter et 

al. 1997, Kellett and Alisauskas 2000, Kellett 

1999, and Kellett and Alisauskas 1997), and 

most of the knowledge has been anecdotal data 

collected incidentally to other studies (Suydam 

2000). Migration counts at Point Barrow, Alaska 

have indicated that the western North American 

population of King Eiders has declined by more 

than 50% between 1976 and 1996 (Suydam et al. 

2000). Similarly, surveys of the western 

Canadian breeding population have shown a 

reduction in breeding pairs (Dickson et al. 1997) 

and Gratto-Trevor et al. (1998) reported an 86% 

decrease between 1975 and 1995 in the number 

of King Eiders nesting in the Rasmussen 

lowlands, NWT. Reasons for the decline are 

unknown, but it corresponds with continentwide declines in other sea duck species (Sea 

Duck Joint Venture 2001). These trends have 

created an increasing interest in the ecology of 

King Eiders. Additionally, the highest known

density of nesting King Eiders on the north slope 

of Alaska occurs within the northeast planning 

area of the National Petroleum Reserve-Alaska 

(NPR-A). The NPR-A is being leased for oil and 

gas exploration and is just beginning to be 

developed. 

We examined the factors that influence nest 

site choice in King Eiders and how nest success 

is affected by these choices. We investigated 

nest site selection by comparing nest site 

characteristics of nests and random points within 

the same study areas. We modeled nest success 

to determine the importance of habitat and social 

factors around the nest site. We examined and 

compared variation in nest success and nest site 

choice between a relatively undisturbed site at 

Teshekpuk Lake and the active oilfield at 

Kuparuk. 

Objectives 

• Document the timing of arrival and 

departure from breeding areas of males, 

females and young. 

• Document habitat use during pre-nesting, 

nesting and brood-rearing and postnesting; 

• Document chronology of nesting, nesting 

success, causes of nest failure, and if 

possible, brood survival. 

• Compare data collected from above 

objectives between Teshekpuk Lake and 

the Kuparuk Oilfields. 

• Evaluate habitat selection through the use 

of vegetation or land cover databases. 

8
Methods 

Study areas 

We included two main study sites on the 

North Slope of Alaska; Teshekpuk Lake and the 

Kuparuk Oil Fields (Fig.1). The Teshekpuk 

Lake study site (70°25' N, 153°07' W) was 10 

km inland from the southeast shore of the lake 

and had experienced very little human impact; 

there was no sign of anthropogenic disturbance 

and no people other than those connected with 

this project were observed during the course of 

the study. The Kuparuk study site (70°20' N, 

149°45' W) was an area on the Arctic Coastal 

Plain between the Colville and Kuparuk rivers 

leased by ConocoPhillips Alaska Inc. and 

actively being developed for oil production. 

Both areas were characterized by numerous 

thaw lakes, ponds and basins. Wetland 

community types included wet sedge (Carex

spp.) meadows, moist sedge-dwarf shrub (Salix

spp.) meadows, and emergent Carex spp. and 

Arctophila fulva on the margins of the lakes and 

ponds (Anderson et al. 1999). Some wetlands at 

Kuparuk were intersected by roads and/or 

created with the closure and rehabilitation of 

gravel pits. 

Field methods 

At Teshekpuk, in both years, all King Eiders 

observed throughout the season were recorded. 

Arrival and departure dates of King Eiders were 

not recorded at Kuparuk due to logistical 

constraints. 

Accessible areas around Teshekpuk Lake 

and Kuparuk were searched for pre-nesting and 

nesting King Eiders during the summers of 2002 

and 2003. Kuparuk had road access between 

wetlands while the Teshekpuk site did not, 

allowing us to search a larger area at Kuparuk 

(Teshekpuk ~1000 ha; Kuparuk ~1500 ha). We 

marked nests with a tongue depressor placed one 

meter from the nest in vegetation so as to be 

concealed from potential nest predators. We 

measured length, width and weight of each egg. 

All eggs were candled in 2003 to estimate stage 

of development (Weller 1956). Latitude and 

longitude were recorded for each King Eider 

nest using a hand-held GPS unit. Habitat type 

within 50 m of each nest was classified posthatch as to type using Bergman’s classification 

system (1977). Vegetation types and frequency 

were recorded within one meter of nests (2002 

and 2003) and at random locations (only 2003) 

within the two study areas. Additionally, we 

recorded island size, distance to the mainland 

and depth of the water if the nest occurred on an 

island. 

King Eiders typically incubate for 22–24 

days and all nests were monitored weekly during 

this period. Hatch success was determined by 

the presence of eggshells with detached 

membranes (Girard 1939) or the presence of 

ducklings. If there were eggshells with no 

membranes or if the entire egg was absent, the 

nest was considered depredated. We attempted 

to determine cause of failure for nests that did 

not succeed. Incubation stage (days) was 

determined from information on egg laying and 

from candling. We calculated nest initiation 

dates by subtracting the estimated age of 

embryos, as determined by candling, plus the 

number of eggs laid into the nest from the date 

of discovery (Grand and Flint 1997). 

To determine brood survival, we captured 

females on nests about one week prior to hatch 

using hand-carried mist nets or bow-net traps. 

Originally we planned to trap twenty females 

randomly selected each year for trapping; 

however, very low nest success of hens required 

that we attempted to trap any female still on a 

nest one week prior to predicted hatch date. In 

2002, we captured twelve females at Kuparuk 

and one female at Teshekpuk. Feathers on the 

upper back between the wings were clipped and 

8-g VHF transmitters were attached to the area 

using epoxy. Due to transmitter loss in 2002, 10-

g VHF transmitters were attached to females 

using an anchor and suture technique in 2003 

(Pietz et al. 1995). We captured and fitted 

twelve hens with transmitters in 2003 at 

Kuparuk and eight at Teshekpuk. We took 

morphometric measurements on all hens and 

each bird was fitted with a USFWS leg band. 

All transmitters were designed to fall off before 

fall migration. All methods and handling of 

9
birds were approved by the University of Alaska 

Institutional Animal Care and Use Committee 

(IACUC # 02-10). 

Radio-transmittered hens were tracked by 

vehicle, foot and air at Kuparuk and on foot at 

Teshekpuk. After hatch, hens were located every 

two to five days until chicks were 30 days old or 

the female was observed twice without a brood. 

Aerial telemetry flights were flown weekly at 

Kuparuk, when weather permitted to locate hens 

not found from the ground. Location information 

was recorded using GPS and aerial photos. We 

also recorded number of ducklings in the brood, 

number of hens and ducklings if broods had 

amalgamated, general behavior, general habitat 

description (Bergman et al. 1977) and any 

predators observed in vicinity. 

10
Data Analysis 

Habitat Use 

The Teshekpuk study area was contained 

within the National Petroleum Reserve-Alaska 

Landcover Inventory database of the Bureau of 

Land Management and Ducks Unlimited. In this 

database, vegetation types were classified as 

follows: clear water, turbid water, ice, Carex 

aquatilis, Arctophila fulva, flooded tundra-low 

centered polygons, flooded tundra-non-pattern, 

wet tundra, sedge/grass meadow, tussock tundra, 

moss/lichen, dwarf shrub, low shrub, tall shrub, 

dunes/dry sand, sparsely vegetated, barren 

ground/other (see appendix for details). Random 

locations within the study area were generated 

using an ArcView extension, Random Point 

Generator. Distances to the perimeter of the 

nearest lake from King Eider nests and the 

random locations were calculated using the 

spatial join option of the extension 

Geoprocessing Wizard. The large cell size (30 

m) made some habitat analyses difficult as nests 

on small islands appeared to be in the water. 

However, vegetation type within 30 m of a nest 

could be compared to random sites and to the 

study area as a whole. Here we report on 

vegetation class availability and use within the 

Teshekpuk study area in 2002. Analyses were 

conducted in ArcView GIS 3.3. 

Nest Site Selection 

Nest site selection was examined by 

comparing the characteristics of nests and 

random points using logistic regression analyses 

at two scales, 1 m and 50 m, at both sites in 

2003. Random locations within the study area 

were generated using an ArcView extension, 

Random Point Generator, visited on foot, and 

habitat variables were recorded (see field 

methods). At the 50 m scale we included the 

following explanatory variables: 

presence/absence of low polygons, low-centered 

polygons, high-centered polygons, peninsulas, 

troughs, strangmoors, and meadows within 50 m 

of the nest or random location; length of the 

closest water body, distance to the closest water 

body, mainland/island location, distance to 

nearest Glaucous Gull (Larus hyperboreus) nest 

and distance to the nearest King Eider nest. We 

used logistic regression analysis and Akaike’s 

Information Criterion values adjusted for a small 

sample size (AICc) to select the best model in 

the candidate model sets. Separate analyses were 

performed for the two sites. We used model 

averaging to derive parameter estimates 

(denoted as θ ± SE) and 95% confidence limits 

from a greater than 92% confidence set of 

candidate models (Burnham and Anderson 

2002). 

At the 1 m scale we included the variable’s 

distance to water and the percentage of the 

following vegetation groups within 1 m of the 

nest or random location: carex, eriophorum, 

salix, dryas, cassiope, moss, ledum and lichen. 

As all of the vegetation types were highly 

correlated with one another, we used principal 

components analysis to reduce the 

dimensionality of the data. We attempted to 

interpret all eigenvalues with a variance > 1. We 

then used the scores of the interpretable 

eigenvectors as explanatory variable in a logistic 

regression analysis. Akaike’s Information 

Criterion values adjusted for a small sample size 

(AICc) were used to select the best model in the 

candidate model sets at both sites separately. 

SAS (SAS Institute 1990) was used for all 

analysis. 

Nest survival 

We used Program MARK to test for site-, year-, 

and island/mainland-specific differences in nest 

survival and to investigate the importance of 

spatial covariates (distance to the nearest 

conspecific nest, distance to the nearest larid 

nest, distance to water, and distance to the 

mainland), as well as any linear trends in time 

throughout the season (T) on daily nest survival 

rates (White and Burnham 1999, Dinsmore et al. 

2002). Linear relationships between covariates 

and daily survival were examined to determine 

what, if any, effect is present. A link function 

was used to characterize the relationship 

between daily nest survival and the covariates. 

We used the logit link as it is the natural link for 

the binomial distribution (McCullagh and Nelder 

1989). We did not adjust for overdispersion, as 

11
no accurate method for estimation exists for 

small sample sizes (Dinsmore et al. 2002). 

Brood rearing 

Movements of females were plotted using 

ArcView GIS (ESRI 1998). Distance between 

resightings and direction of brood movements 

were calculated using Animal Movement 

extension (Hooge and Eichenlaub 1997) in 

ArcView. We considered survival of a brood as 

one duckling in a brood surviving to 30 days of 

age. Amalgamation of broods was not extensive 

at either study site. When brood amalgamation 

was observed, we considered a radiotransmittered hen to still have a brood if 

ducklings of the appropriate age tended to 

follow her when disturbed rather than alternate 

hens. Linear regression was used to test whether 

the number of days a brood survived was 

affected by distances traveled each day at 

Kuparuk (small sample size at Teshekpuk 

precluded analysis). Means are presented ± SE. 

Data from both years are combined in all 

analyses, due to small sample sizes. All 

statistical analyses were performed using SAS 

software (SAS Institute 1990). 

12
Results 

Upon our arrival at the Teshekpuk study site 

(7 June 2002, 11 June 2003), King Eiders were 

present in an equal ratio of males to females. 

The sex ratio continued to be about equal until 

after 19 June in 2002 and slightly later (25 June) 

in 2003, when males began to depart the study 

area. No males were seen in the study area after 

28 June 2002 and 8 July 2003 (Fig. 2). We 

found and monitored 39 – 44 active nests each 

year at each site. Initiation of incubation in 2003 

ranged from 5 – 30 June at Kuparuk with most 

females beginning incubation around 25 June. 

Initiation ranged from 11 June to 4 July with 

most females beginning incubation around 23 

June at Teshekpuk in 2003 (Fig. 3). Nest 

initiation was not different between Kuparuk 

and Teshekpuk in 2003 (t = -0.75, P < 0.46). 

Most nests were found during laying at both 

sites in 2003 and more than 60% of nests were 

found in the first week of incubation (Fig. 4). 

Habitat Use 

Based on the landcover database, the percent 

covers of the dominant vegetation types within 

the study area were as follows: clear water 

(14%), turbid water (17%), Carex aquatilis 

(10%), sedge meadow (23%), and tussock 

tundra (14%) (Fig. 5). However, there were 

numerous small islands in some of these lakes 

that did not show up on the landcover map 

because they were smaller than the cell size of 

30 m. 

Forty seven King Eider nests were located in 

a variety of habitat types during nest searches at 

Teshekpuk in 2002. The distribution of nests 

throughout the study area appeared to be 

clumped with nests occurring in and around 

lakes. Analysis of the vegetation type of the 

landcover gridcell that each King Eider nest was 

located in indicated that nests occurred most 

often in turbid water (40%), followed by clear 

water (28%; Fig. 5). These nests were not in the 

water, as it would seem from the database, but 

on islands with the dominant habitat type within 

30 m being either clear or turbid water. The 

flooded tundra low-center polygon vegetation 

type was also used more frequently (12%) than 

it occurred within the study site. However, this 

was a much smaller difference in availability 

and use than seen for clear and turbid water. 

King Eider nests occurred 24.4 ± 0.97 (m, 

SE) from the shoreline of either clear or turbid 

lakes. Random locations throughout the study 

area fell 81.2 ± 2.1 (m, SE) from lakes. Nests 

and random points that fell within the borders of 

a lake were assigned the distance of zero to the 

border of that lake. Eider nests were located 

primarily on islands (70.8%) but peninsulas and 

other landforms were also used. Nests that 

appeared to be within the boundaries of lakes 

(on islands) were 60.4 ± 1.2 (m, SE) from the 

shore. 

Nest Site Selection 

Teshekpuk – The logistic regression model 

at the 50 m scale for Teshekpuk in 2003 that 

best discriminated between occupied and 

unoccupied nest sites included island/mainland 

location, presence of a low polygon within 50 m, 

length of the closest waterbody and distance to 

nearest conspecific (Table 1). There are four 

candidate models within 2 AICc values from the 

best approximating model, all of which included 

the variables in the top model. A HosmerLemeshow Goodness-of-Fit (χ

2

 = 8.86, P = 

0.26) test indicated a good fit of the data to the 

logistic model. Nest sites were more likely to be 

on islands near larger lakes, and unlikely to be 

found near other eider or low polygons (Table 

2). However, none of these model-averaged 

parameter estimates were significant. 

Principle components analysis of the 

vegetation types within 1 m of the nest site 

revealed five eigenvalues with a variance greater 

than one. We interpreted the factor loadings as 

the following habitat types; dry tussock tundra 

dominated by eriophorum, lichen and forbs 

(tussock), moist tundra dominated by cassiope 

(moist), dry tundra dominated by cassiope and 

dryas (dry), dry tundra dominated by salix and 

carex (dry salix), and moist tundra dominated by 

salix (moist salix; Table 3). The logistic 

regression model that best described nest sites at 

the 1 m scale included the habitat types: tussock, 

moist, dry salix, and moist salix (Table 4). The 

best approximating model was 2.29 AICc units 

13
from the next best model indicating high support 

for the top model. A Hosmer-Lemeshow 

Goodness-of-Fit (χ

2

 = 5.13, P = 0.74) test 

indicated a good fit of the data to the logistic 

model. King Eiders tended to select nest sites in 

moist tundra or moist salix dominated tundra 

and to avoid tussock tundra dominated sites 

(Table 5). 

Kuparuk – Nest site choice of King Eiders at 

Kuparuk in 2003 revealed a slightly different 

pattern from Teshekpuk. The logistic regression 

model at the 50 m scale that best discriminated 

between occupied and unoccupied nest sites 

included presence of high center polygons, 

troughs and peninsulas within 50 m, and 

distance to water, conspecifics and Glaucous 

Gulls (Table 6). There are an additional four 

models within 2 AICc values from the top model 

causing model selection uncertainty. However, 

the variables in the top model appear in 4 of 5 

top models. A Hosmer-Lemeshow Goodness-ofFit (χ

2

 = 1.97, P = 0.96) test indicated a good fit 

of the data to the logistic model. Nest sites were 

more likely to be found near conspecific nests, 

Glaucous Gulls, peninsulas and on islands; and 

were unlikely to be found very close to water, 

troughs or high center polygons (Table 7). 

However, only the model-averaged parameter 

estimate of trough was significant. 

Principle components analysis of the 

vegetation types within 1 m of the nest site 

revealed five eigenvalues with a variance greater 

than one. We interpreted the factor loadings as 

the following habitat types; dry tundra 

dominated by ledum and lichen (dry), dry tundra 

dominated by salix and moss (dry salix), moist 

tundra dominated by salix and dryas (moist 

salix), moist tundra dominated by carex (carex 

meadow), and moist forb dominated tundra 

(moist forb; Table 8). Some of the habitat 

classifications were similar to those at 

Teshekpuk, and have the same titles; however, 

factor loadings do not exactly correspond 

between the two sites. The logistic regression 

model that best described nest sites at the one 

meter scale included dry, dry salix, moist salix, 

and carex meadow vegetation classifications 

(Table 9). The top model is only 0.29 AIC 

values from the next best model, which does not 

have an effect of dry salix. A HosmerLemeshow Goodness-of-Fit (χ

2

 = 7.9, P = 0.34) 

test indicated a good fit of the data to the logistic 

model. King Eiders at Kuparuk in 2003 tended 

to avoid choosing sites in dry, dry salix and in 

the moist salix dominated tundra, and select 

carex meadow tundra (Table 10). However, only 

the model-averaged parameter estimate of the 

dry vegetation classification was significant. 

Nest success 

The daily survival of King Eider nests was a 

function of both the island vs. mainland nest 

location, and the site, Teshekpuk vs. Kuparuk 

(Table 11). Nests on islands had significantly 

higher daily survival than those on the mainland 

(Table 12). The estimate from the best model for 

the additive effect on survival of nests on islands 

compared to those on the mainland was βisland = 

0.66 (1 SE = 0.21, 95% CL = 0.26, 1.06) on a 

logit scale and this coefficient was always 

positive in models with island effects. Models 

incorporating site received substantial support; 

Kuparuk was always slightly higher than 

Teshekpuk, but not significantly so. Models with 

linear trends on nest survival received some 

support; quadratic trends received slightly less 

support. The confidence intervals for the 

coefficients of both the linear and quadratic 

trends included zero. Daily nest survival 

increased throughout the season at Teshekpuk 

ΒT(Teshekpuk) = 0.02 (1 SE = 0.02, 95% CL = 

-0.03, 0.06) and decreased at Kuparuk 

ΒT(Kuparuk)= -0.02 (1 SE = 0.02, 95% CL = -0.06, 

0.02; Fig.6). There was no evidence of year 

effects on nest survival. There was some support 

for an effect of distance to the nearest other King 

Eider nest βconspecifc at Kuparuk = 0.12 (1 SE = 0.13, 

95% CL = -0.13, 0.37), and βconspecific at Teshekpuk = 

-0.09 (1 SE = 0.21, 95% CL = -0.50, 0.33). 

However, confidence intervals for the 

coefficients included zero for both Teshekpuk 

(survival decreased as conspecific distance 

increased) and Kuparuk (survival increased with 

conspecific distance), and thus the estimated 

effect was slight. Most nest failure was due to 

depredation and usually all the eggs were gone; 

there were no shells left in the nest, and no 

tracks. Since we observed foxes, Glaucous Gulls 

and Common Ravens (Corvus corax) 

transporting entire eggs it is impossible to 

14
determine with any certainty which nest 

predators were responsible. 

Brood rearing 

Teshekpuk – Unfortunately, tracking brood 

movements at Teshekpuk was not successful in 

2002. The one female that was transmittered 

successfully hatched but left the study area 

immediately and we were unable to follow her 

due to our inability to efficiently track on foot; 

bad weather precluded aerial tracking. Eight 

hens were trapped at Teshekpuk in 2003. Of 

these hens, only three successfully hatched eggs. 

Two of the hens with broods were followed for 

over a week before they traveled too far away to 

be located on foot. Both broods remained in 

marshes within 1 km of their nest site for 

approximately one week. One brood appeared to 

be heading north before we could no longer find 

it, while the other did not have a clear direction 

of movement. Both of these hens still had chicks 

when they where last located. We failed to 

locate the third female and her brood after hatch. 

No broods were relocated at 30 days of age or 

greater.

Kuparuk – Of the hens captured in 2002, 

five were successfully radio-tracked with broods 

at Kuparuk. Of the hens transmittered in 2002 

that were not tracked, four failed to successfully 

hatch eggs and three prematurely dropped their 

radio transmitters. In 2003, six hens were 

successfully tracked. Of the hens transmittered 

in 2003 that were not radio-tracked, three failed 

prior to hatch and three lost broods prior to first 

relocation after hatch. Apparent brood survival 

to 30 days of age was 20% (n = 10). Broods 

survived 13.4 ± 3.1 days (n = 10) on average. 

Mean daily movement rates of hens with broods 

were 470 ± 61.7 m/day (n = 10, range 178.3 – 

826.9 m). Longer daily movement rates did not 

affect the number of days a brood survived (F = 

1.51, P = 0.25). 

Two radioed hens with broods were 

observed in crèches. These hens were the only 

two that successfully raised young to 30 days. 

One hen hatched five ducklings, but was later 

observed with three King Eider and three 

Spectacled Eider (Somateria fischeri) chicks. 

Ultimately this hen was observed in a crèche of 

up to 40 hens and 12 young. We believe some of 

these ducklings were still associated with the 

radioed hen based on behavioral observations. 

When the crèche was disturbed, we observed 

that hens still associated with broods would split 

from the larger group and move toward shore 

with young. The second hen that successfully 

raised two ducklings to 30 days formed a small 

crèche with one other hen with a brood of two 

chicks. The two broods were discernable by 

their different size, with our hen having smaller, 

younger ducklings than the hen with which she 

formed a crèche. 

15
Discussion 

Timing 

Males departed the study areas as females 

began incubation and were not usually seen in 

July. The time of departure of males varied 

slightly between years, this is likely correlated 

with initiation of incubation and spring 

conditions. We observed groups of females 

without ducklings in mid- to late-July. 

Presumably these were failed nesters that group 

up prior to leaving the breeding areas. We were 

unable to adequately document the timing of 

departure from the breeding sites for females 

with young. However, the few females that we 

followed at Teshekpuk appeared to leave the 

study area very quickly after hatch. Kuparuk 

females experienced low brood survival but 

survival was not correlated with distance moved 

per day. It is unknown where the broods moved, 

what habitats they used, and what factors 

effected duckling survival, especially at 

Teshekpuk. These questions are very important 

in the face of future development on the North 

Slope of Alaska. However, given the extremely 

low nest success of King Eider, it will be 

difficult to ever obtain an adequate sample size 

for brood survival analysis or habitat selection 

analysis. Possibly aerial surveys could identify 

important brood rearing lakes. 

Habitat Use 

Ducks Unlimited Inc. (1998) found that 

King Eiders select most strongly for Carex 

aquatilis and Arctophila fulva while avoiding 

ice, tussock tundra, dwarf shrub, dry sand, 

sparsely vegetated and barren ground habitat 

types within the NPR-A. The Ducks Unlimited 

study used the same land cover database that 

was used in the present study. Within the study 

area southeast of Teshekpuk, King Eiders 

selected most strongly for the islands in clear 

and turbid water. This may be due to nest 

predator avoidance, as foxes are the main 

predator in the area and are probably somewhat 

deterred by having to swim out to a nest. King 

Eiders did not select strongly for Arctophila 

fulva as was seen in the Ducks Unlimited study, 

however, very little of this land cover class 

actually occurred in this area. King Eiders also 

did not select for Carex aquatilis, using it less 

often than it occurred in the study area. There 

may be several explanations for this divergence 

from Ducks Unlimited’s results. One difference 

was the scale; they examined the entire NPR-A, 

relying on aerial surveys, while we concentrated 

on a smaller area, covering it on foot. The results 

from our study do offer further support that the 

King Eiders are not selecting tussock tundra. We 

cannot look at the preference or avoidance of 

some of the other land cover classes because of 

their low occurrence within the study area. 

Additionally, we used nest sites that we knew 

the location of with certainty; Ducks Unlimited 

used locations of pairs located during aerial 

surveys. Pairs may flush away from an 

oncoming aircraft and the location recorded may 

not be the area they originally selected. Pairs 

have been observed resting and feeding in areas 

that are some distance from the actual nest site, 

causing an estimation of breeding pair habitat 

selection, not nest site choice. 

King Eider nests on islands within lakes 

were found to be closer to the shore than random 

locations within lakes in the study area. This 

may have more to do with the distribution of the 

islands within the lakes than to the selection of 

islands by eiders. The method of generating 

random locations within the lakes did not take 

into consideration whether an island actually 

occurred under them or not. This is because 

most islands cannot be detected at this pixel size. 

For this same reason we could not compare 

vegetation classes between the islands that the 

King Eiders selected and those that they did not. 

This is a shortfall of the landcover data base and 

one that should be addressed in future studies. 

Nest site selection and nest success 

King Eiders at Teshekpuk selected nest sites 

on islands in or near larger lakes, away from 

other nesting King Eiders, and avoided low 

polygons. However, individual model-averaged 

parameter estimates were largely insignificant. 

At the microhabitat level eiders selected nest 

sites in moist tundra or moist salix-dominated 

tundra and to avoid tussock-tundra dominated 

sites. King Eiders at Teshekpuk had higher nest 

16
success on islands. This was likely due to fewer 

nesting on an island and would not confer any 

protection from avian predators. 

King Eider nest sites at Kuparuk were more 

likely to be found near conspecific nests, 

Glaucous Gulls, peninsulas and on islands; and 

were unlikely to be found very close to water, 

troughs or high center polygons (Table 7). 

However, only the model-averaged parameter 

estimate of trough was significant. Troughs are 

largely associated with drier areas dominated by 

high center polygons (pers obs) and it is likely 

that eiders are not so much avoiding troughs as 

selecting areas that do not have troughs, i.e. 

complex (islands and peninsulas) wetland 

basins. At the microhabitat scale, King Eiders at 

Kuparuk avoided choosing sites in the dry 

vegetation classification. Again, this is an 

indication that they choose areas away from the 

dry troughs and high center polygons. Similarly, 

nests on islands at Kuparuk experienced higher 

success. 

We were unable to determine causes of nest 

failure from sign at depredated nests. We 

recommend that future work further investigate 

the causes of nest failure and determine if 

mammalian or avian predators are having a 

greater effect on nest success. Video systems 

would likely be the best method to accomplish 

this, given the problems plaguing motiontriggered camera systems and physical clues left 

at nest sites. It has been suggested that an effect 

of development is increased densities of 

predators in the oilfields. These predators prey 

on the eggs, nestlings and fledglings of many 

birds, including King Eiders (Lamothe 1973, 

Larson 1960, and Kellett and Alisauskas 1997). 

In order to manage and mitigate the effects of oil 

development it is very important that we 

understand factors influencing nest success.

17
Summary 

Prior to this study, there was little known 

about King Eider breeding biology (Kellett and 

Alisauskas 1997, Kellett 1999, Lamothe 1973) 

and what was known was from a semi-colonial 

island nesting population in arctic Canada 

(Kellett and Alisauskas 1997, Kellett 1999). In 

what is likely a more typical scenario across the 

breeding range of King Eider, we found King 

Eiders nesting dispersed and solitary on very 

small islands in tundra thaw lakes, and near the 

margins of these lakes. King Eiders often nested 

on islands, probably to avoid nest predators. We 

found that King Eider selected sites where the 

microhabitat was moist (close to water), 

potentially for predator avoidance or easy access 

to food sources. We determined that nest success 

was low at both study sites; this was not 

surprising for a long-lived, large-bodied species. 

Brood survival was also low and females with 

broods left the breeding areas fairly soon after 

hatch. At this point we do not know where King 

Eider broods go during the brood rearing period, 

and this knowledge could be important to 

mitigate and minimize any impacts of oil 

extraction on the North Slope of Alaska. 

We cannot make direct implications of any 

effect of oil development with this study because 

we included only one developed and one 

undisturbed site. The differences we found could 

be an effect of distance to coast, habitat quality, 

size of wetlands, or a number of other factors 

including anthropogenic disturbance. 

Regardless, we feel that these data were critical 

for a baseline understanding of the nesting 

ecology of King Eider. Additionally, our study 

provided an excellent baseline data set if 

development proceeds in the Teshekpuk area. 

18
Acknowledgements 

This study would not be possible without the 

financial and logistical support of Coastal 

Marine Institute, Minerals Management Service, 

ConocoPhillips Alaska, Inc., University of 

Alaska Foundation Angus Gavin Grant, USGS 

Alaska Cooperative Fish and Wildlife Research 

Unit, and the North Slope Borough. This study 

was endorsed by the Sea Duck Joint Venture. 

We thank Chuck Monnett, Jeff Gleason, Doloros 

Vinas, Liza DelaRosa, April Brower, Benny 

Akootchook, Justin Harth, and Anne Lazenby 

for logistical help; Yumiko Uchiro, Kim Hanish, 

Qiayaan Opie, Bonnie Rogers, Lori Gildehaus, 

and Rita Frantz for their help as field 

technicians; and ABR for cooperation at 

Kuparuk. We also thank Jeff Gleason and two 

anonymous for their comments on this report. 

19
Study products 

Presentations: 

McGuire, R. and A. Powell. 2005. Incubation 

behavior of king eiders on the North Slope 

of Alaska. Annual Meeting, Pacific 

Seabird Group/Waterbird Society 

Meeting, 19–23 January, Portland, OR. 

McGuire, R., A. Powell, and R. Suydam. 2005. 

Breeding biology and habitat use of king 

eiders on the coastal plain of northern 

Alaska. 10th Annual MMS Information 

Transfer Meeting, Anchorage, AK. 

McGuire, R. L., R. Suydam, and A. N. Powell. 

2005. Breeding biology and habitat use of 

king eider on the coastal plain of northern 

Alaska. CMI Annual Research Review, 

University of Alaska, Fairbanks, AK. 

McGuire, R. L., L. Phillips, R. Suydam, and A. 

N. Powell. 2004. Breeding biology and 

habitat use by king eider (Somateria 

spectabilis) at Teshekpuk Lake and 

Kuparuk oilfields on the North Slope of 

Alaska. CMI Annual Research Review, 

University of Alaska, Fairbanks, AK. 

McGuire, R., L. Phillips, A. N. Powell, and R. 

Suydam. 2004. Factors influencing king 

eider nest survival on Alaska's North 

Slope. 16 March 2004, Alaska Bird 

Conference, Anchorage, AK. 

Knoche, M., R. McGuire, L. Phillips, and H. 

Wilson. 2004. Alaska's eiders. 

Presentation at Alaska Bird Observatory’s 

seminar series. 

McGuire, R. L., L. Phillips, R. Suydam, and A. 

N. Powell. 2004. Breeding biology and 

habitat use of king eiders on the coastal 

plain of northern Alaska. 

McGuire, R. L., L. Phillips, R. Suydam, and A. 

N. Powell. 2003. Breeding biology and 

habitat use by king eider (Somateria 

spectabilis) at Teshekpuk Lake and 

Kuparuk oilfields on the North Slope of 

Alaska. CMI Annual Research Review, 

University of Alaska, Fairbanks, AK. 

McGuire, R. L., L. Phillips, R. Suydam, and A. 

N. Powell. 2002. Breeding biology and 

habitat use by king eider at Teshekpuk 

Lake and Kuparuk oil fields on the north 

slope of Alaska. Poster; North American 

Sea Duck Conference, 6–10 November 

2002, Victoria, B.C. 

Powell, A. N. 2002. Ecology of king eiders on 

Alaska's North Slope. Oral paper 

presented at the MMS Information 

Transfer Seminar, Anchorage, AK. 

Reports: 

Powell, A. N., R. Suydam, and R. McGuire. 

2004. Breeding Biology of King Eiders on 

the Coastal Plain of Northern Alaska. 

Annual Report, CMI, University of 

Alaska, Fairbanks. 

Powell, A. N., R. Suydam, R. McGuire, and L. 

Phillips. 2004. Breeding biology and 

habitat use of King Eiders on the Coastal 

Plain of Northern Alaska. Report to the 

Sea Duck Joint Venture, Endorsed Study 

No. 25. 

http://www.seaduckjv.org/ssna.html

Powell, A. N., R. Suydam, and R. McGuire. 

2003. Breeding Biology of King Eiders on 

the Coastal Plain of Northern Alaska. 

Annual Report, CMI, University of 

Alaska, Fairbanks. 

Powell, A. N., R. Suydam, R. McGuire, and L. 

Phillips. 2003. Breeding biology and 

habitat use of King Eiders on the Coastal 

Plain of Northern Alaska. Report to the 

Sea Duck Joint Venture, Endorsed Study 

No. 25. 

http://www.seaduckjv.org/ssna.html 

Powell, A. N., R. Suydam, and R. McGuire. 

2002. Breeding Biology of King Eiders on 

the Coastal Plain of Northern Alaska. 

Annual Report, CMI, University of 

Alaska, Fairbanks. 

20
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22
Appendix 

Clear Water – Fresh or saline waters with 

little or no particulate matter. Clear water areas 

are typically deep (greater than 1 m). The clear 

water class may contain small amounts of 

Arctophila fulva or Carex aquatilis but generally 

less than 15% surface coverage of these species. 

Turbid Water – Waters that contain 

particulate matter or shallow (<1m), clear water 

bodies that are spectrally different from class 

1.1. This class typically occurs in shallow lake 

shelves, deltaic plumes, and rivers and lakes 

with high sediment loads. The turbid water class 

may contain small amounts of Arctophila fulva

or Carex aquatilis but generally less than 15% 

surface coverage of these species. 

Ice – May last into late summer on lakes and 

larger ponds. Ice is present year round in many 

of the larger lakes. 

Carex aquatilis – Associated with lake or 

pond shorelines and composed of 50 – 80% 

clear or turbid water that was greater than 10 

centimeters deep. The dominant species was 

Carex aquatilis. A small percentage of 

Arctophila fulva, Hippuris vulgaris, Potentilla 

palustris, and Caltha palustris may be present. 

Arctophila fulva – Associated with lake or 

pond shorelines and composed of 50 – 80% 

clear or turbid water that was greater than 10 

centimeters deep. The dominant species was 

Arctophila fulva. A small percentage of Carex 

aquatilis, Hippuris vulgaris, Potentilla palustris, 

and Caltha palustris may also be present. 

Flooded Tundra–Low Centered Polygons – 

Polygon features that retain water throughout the 

summer. This class is composed of 25 – 50% 

water; Carex aquatilis is the dominant species in 

the permanently flooded areas. The dryer ridges 

of the polygons are composed mostly of 

Eriophorum russeolum, Eriophorum vaginatum, 

Sphagnum spp., Salix spp., Betula nana, 

Arctostaphylos spp., and Ledum palustre. 

Flooded Tundra–Non-pattern – 

Continuously flooded areas composed of 25 –

50% water. Carex aquatilis was the dominant 

species. Other species may include Hippuris 

vulgaris, Potentilla palustris, and Caltha 

palustris. Non-pattern is distinguished from low 

centered polygons by the lack of polygon 

features and associated shrub species that grow 

on the dry ridges of low centered polygons. 

Wet Tundra – Associated with areas of 

super saturated soils and standing water. Wet 

tundra often floods in early summer and 

generally drains of excess water during dry 

periods but remains saturated throughout the 

summer. It is composed of 10 – 25% water; 

Carex aquatilis is the dominant species. Other 

species may include Eriophorum angustifolium, 

and other sedges, grasses, and forbs. 

Sedge/Grass Meadow – Dominated by the 

sedge family. This class commonly consists of a 

continuous mat of sedges and grasses with a 

moss and lichen understory. The dominant 

species were Carex aquatilis, Eriophorum 

angustifolium, Eriophorum russeolum, 

Arctagrostis latifolia and Poa arctica. 

Associated genera include Cassiope spp., Ledum

spp., and Vaccinium spp.. 

Tussock Tundra – Dominated by the 

tussock-forming sedge Eriophorum vaginatum. 

Tussock tundra is common throughout the 

Arctic Foothills and may be found on welldrained sites in all areas of the NPR-A. 

Cottongrass tussocks are the dominant landscape 

elements, while moss is the common understory. 

Lichen, forbs and shrubs are also present in 

varying densities. Associated genera include 

Salix spp., Betula nana, Ledum palustre, and 

Carex spp.. 

Moss/Lichen – Associated with low lying 

lakeshores and dry sandy ridges dominated by 

moss and lichen species. As this type grades 

into a sedge type, graminoids such as Carex 

aquatilis may increase in cover, forming an 

intermediate zone. 

Dwarf Shrub – Associated with ridges and 

well drained soils and dominated by shrubs less 

than 30 centimeters in height. Because of the 

relative dryness of the sites on which this cover 

type occurs, it is the most species diverse. 

Major species included Salix spp., Betula nana, 

Ledum palustre, Dryas spp., Vaccinium spp., 

Arctostaphylos spp., Eriophorum vaginatum, 

and Carex aquatilis. This class frequently 

occurs over a substrate of tussocks.

23
Figures 

Figure 1. Teshekpuk and Kuparuk study areas on the coastal plain of northern Alaska. King Eider nest 

locations in 2002 are indicated in green and yellow.

24
0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

6/8

6/12

6/16

6/20

6/24

6/28

7/3

7/7

7/11

7/15

7/19

7/23

Ratio of Male to Female King Eider

Figure 2. The change in sex ratios of King Eiders observed at Teshekpuk Lake in June and July 2002 

(grey line, n = 1589) and 2003 (black line, n = 832). 

25
0

1

2

3

4

5

6

7

2-Jun

4-Jun

6-Jun

8-Jun

10-Jun

12-Jun

14-Jun

16-Jun

18-Jun

20-Jun

22-Jun

24-Jun

26-Jun

28-Jun

30-Jun

2-Jul

4-Jul

6-Jul

Number of Nests Initiated

Figure 3. Initiation of egg-laying for King Eider females at Teshekpuk (white, n = 40) and Kuparuk 

(black, n = 39), Alaska, 2003. 

26
0

3

6

9

12

15

18

21

0 3 6 9 12 15 18 21

Nest Age When Found

Number of Nests

Figure 4. Age of King Eider nests when found in 2003 at Kuparuk (black, n = 39) and Teshekpuk (white, 

n = 40), Alaska. 

27
0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

Clear water Arctophila

fulva

Wet tundra Moss/Lichen Dunes

Percent Vegetation Type

Figure 5. Percent of vegetation types within the entire study area and within 30 m of King Eider nests at 

Teshekpuk, Alaska, 2002. 

28
0.85

0.9

0.95

1

1 5 9 13 17 21 25 29 33 37

Day

Daily Nest Survival

Figure 6. Daily nest survival with a linear trend throughout the season for Teshekpuk (grey line) 

ΒT(Teshekpuk) = 0.02 (1SE= 0.02, 95% CL = -0.03, 0.06) and Kuparuk (black line) ΒT(Kuparuk)= -0.02 (1SE= 

0.02, 95% CL = -0.06, 0.02) for nests on islands (Ssite*T+island). 

29
Table 1. General linear models of nest site selection by King Eiders nesting at Teshekpuk, Alaska, in 

2003, with corresponding AICc, ΔAICc, number of parameters (K), model weight (wi), and coefficient of 

determination (r

2

). Models are sorted by AICc, and those included in the 95% confidence set (sum of wi

=0.95) and the global model are shown. Model parameters of low polygon (LP), low center polygon 

(LCP), high center polygon (HCP), peninsula, trough, and meadow all refer to the presence of these 

landforms within 50 m of the nest or random location; length, distance, island, gull and conspecific refer 

to length of the closest water body, distance to the closest water body, mainland/island location, distance 

to nearest gull, and distance to the nearest other King Eider, respectively. 

Model K AICc Δ AICc wi r

2

LP, Length, Island, Conspecific 5 82.56 0 0.26 0.38 

LP, Peninsula, Length, Island, Gull, 

Conspecific 7 83.58 1.01 0.16 0.41 

LP, LCP, HCP, Peninsula, Length, Island, 

Gull, Conspecific 9 83.68 1.12 0.15 0.44 

LP, HCP, Peninsula, Length, Island, Gull, 

Conspecific 8 83.96 1.40 0.13 0.42 

LP, Length, Island, Gull, Conspecific 6 84.18 1.61 0.12 0.39 

LP, HCP, Peninsula, Length, Distance, 

Island, Gull, Conspecific 9 85.53 2.97 0.06 0.43 

LP, LCP, HCP, Peninsula, Length, Distance, 

Island, Gull, Conspecific 10 85.74 3.18 0.05 0.45 

Length, Island, Conspecific 4 87.07 4.51 0.03 0.33 

Length, Island, Gull, Conspecific 5 87.92 5.36 0.02 0.34 

LP, LCP, HCP, Peninsula, Trough, Distance, 

Length, Island, Gull, Conspecific 11 87.98 5.42 0.02 0.45 

Global 12 90.57 8.01 0.01 0.45 

30
Table 2. Model-averaged parameter estimates (θ), standard errors, and 95% confidence intervals derived 

from the 95% confidence set of candidate models from the logistic regression analysis of King Eider nest 

sites and random unoccupied sites at Teshekpuk, Alaska, 2003. See Table 1 for parameter definitions. 

Parameter θ SE 95% CI 

LP -2.20 1.16 -4.8 to 0.4 

LCP -0.28 0.18 -0.69 to 0.12 

HCP -0.59 0.38 -1.44 to 0.26 

Peninsula 0.63 0.43 -0.34 to 1.59 

Length 0.00 0.00 -0.00 to 0.00 

Distance 0.00 0.00 -0.01 to 0.00 

Island 0.96 0.78 -0.77 to 2.7 

GLGU 0.08 0.10 -0.13 to 0.3 

Conspecific 0.00 0.00 -0.00 to 0.00 

31
Table 3. Factor loadings and eigenvalues from principal components analysis (PCA) of the variable’s 

distance to water, and the percentage of the following vegetation groups within 1 m of the nest or random 

location: carex, eriophorum, salix, dryas, cassiope, moss, ledum and lichen, Teshekpuk 2003. We 

interpreted the factor loadings of the principal components with a variance greater than one as the 

following habitat types; dry tussock tundra dominated by eriophorum, lichen and forbs (tussock), moist 

tundra dominated by cassiope (moist), dry tundra dominated by cassiope and dryas (dry), dry tundra 

dominated by salix and carex (dry salix), and moist tundra dominated by salix (moist salix). 

 Tussock Moist Dry Dry salix Moist salix 

Distance to 

water 0.26 -0.56 0.21 0.19 -0.06 

% carex -0.25 0.13 -0.38 0.48 -0.52 

% eriophorum 0.39 -0.57 -0.04 0.08 0.01 

% salix -0.19 0.08 -0.02 0.32 0.83 

% dryas 0.19 0.29 0.59 0.18 -0.11 

% cassiope 0.32 0.35 0.41 -0.01 -0.09 

% moss -0.32 -0.12 0.11 -0.73 -0.06 

% ledum 0.44 0.15 -0.47 -0.20 0.08 

% lichen 0.49 0.29 -0.27 -0.14 0.08 

Eigenvalue 2.12 1.42 1.35 1.21 1.07 

32
Table 4. General linear models of nest site selection by King Eiders at the 1 m scale, with corresponding 

AICc, ΔAICc, , number of parameters (K), model weight (wi), and coefficient of determination (r

2

), 

Teshekpuk, Alaska, 2003. Models are sorted by AICc and all candidate models are shown. Model 

parameters include tussock, moist, dry, dry salix, and moist salix habitat types. 

Model K AICc Δ AICc wi r

2

Tussock, Moist, Dry salix, Moist salix 5 97.71 0.00 0.71 0.33 

Tussock, Moist, Dry, Dry salix, Moist 

salix 

(Global model) 6 100.01 2.29 0.22 0.33 

Tussock, Dry salix, Moist salix 4 103.46 5.75 0.04 0.27 

Tussock, Moist salix 3 103.96 6.24 0.03 0.25 

Tussock 2 113.30 15.59 0.00 0.15 

Moist salix 2 116.58 18.87 0.00 0.12 

Dry salix 2 124.79 27.08 0.00 0.02 

Moist salix 2 125.89 28.17 0.00 0.02 

Dry 2 127.34 29.63 0.00 0.01 

33
Table 5. Model-averaged parameter estimates (θ), standard errors and 95% confidence intervals derived 

from the 99% confidence set of candidate models from the logistic regression analysis of King Eider nest 

sites and random unoccupied sites at the 1 m scale at Teshekpuk, Alaska, 2003. See Table 3 for parameter 

definitions. 

Parameter θ SE 95% CI 

Tussock -1.09 0.37 -1.91 to -0.28 

Moist 1.18 0.51 0.04 to 2.32 

Dry 0.00 0.07 -0.15 to 0.16 

Dry Salix -0.62 0.28 -1.26 to 0.01 

Moist Salix 0.98 0.34 0.22 to 1.73 

34
Table 6. General linear models of nest site selection by King Eiders nesting at Kuparuk, Alaska, in 2003, 

with corresponding AICc, ΔAICc, number of parameters (K), model weight (wi), and coefficient of 

determination (r

2

). Models are sorted by AICc, and those included in the 92% confidence set (sum of wi

=0.92) and the global model are shown. Model parameters of low polygon (LP), low center polygon 

(LCP), high center polygon (HCP), strangmoor, peninsula, trough, and meadow all refer to the presence 

of these landforms within 50 m of the nest or random location; length, distance, island, gull, and 

conspecific refer to length of the closest water body, distance to the closest water body, mainland/island 

location, distance to nearest gull and distance to the nearest other King Eider, respectively. 

 

Model K AICc Δ AICc wi r

2

HCP, Peninsula, Trough, Distance, 

Gull, Conspecific 7 57.16 0.00 0.22 0.53 

HCP, Peninsula, Trough, Island, 

Distance, Gull, Conspecific 8 57.50 0.35 0.18 0.55 

LP, LCP, HCP, Strangmoor, 

Peninsula, Trough, Distance, Island, 

Gull, Conspecific 11 57.72 0.56 0.17 0.60 

Trough, Distance, Gull, Conspecific 5 57.76 0.60 0.16 0.49 

HCP, Strangmoor, Peninsula, Trough, 

Distance, Island, Gull, Conspecific 9 58.36 1.20 0.12 0.56 

Peninsula, Trough, Distance, Gull, 

Conspecific 6 59.26 2.11 0.08 0.50 

Global 12 60.48 3.33 0.04 0.60 

35
Table 7. Model-averaged parameter estimates (θ), standard errors, and 95% confidence intervals derived 

from the 92% confidence set of candidate models from the logistic regression analysis of King Eider nest 

sites and random unoccupied sites at Kuparuk, Alaska, 2003. See Table 6 for parameter definitions. 

Parameter θ SE 95% CI 

LP 0.22 0.65 -0.1 to 1.27 

LCP 0.58 0.31 -1.23 to 1.67 

HCP -1.79 1.15 -4.36 to 0.78 

Strangemoor -0.47 0.41 -1.39 to 0.44 

Peninsula 0.86 0.99 -1.36 to 3.09 

Trough -3.57 1.49 -6.9 to -0.23 

Distance -0.05 0.05 -0.15 to 0.05 

Island 0.70 0.48 -0.38 to 1.78 

GLGU 0.00 0.01 -0.01 to 0.02 

Conspecific 0.00 0.01 -0.01 to 0.02 

36
Table 8. Factor loadings and eigenvalues from principal components analysis (PCA) of the variable’s 

distance to water, and the percentage of the following vegetation groups within 1 m of the nest or random 

location: carex, eriophorum, salix, dryas, cassiope, moss, ledum and lichen, Kuparuk 2003. We 

interpreted the factor loadings as the following habitat types; dry tundra dominated by ledum and lichen 

(dry), dry tundra dominated by salix and moss (dry salix), moist tundra dominated by salix and dryas 

(moist salix), moist tundra dominated by carex (carex meadow), and moist forb dominated tundra (moist 

forb). 

 Dry Dry salix Moist salix 

Carex 

meadow Moist forb 

Distance to 

water 0.53 0.22 0.18 -0.02 -0.19 

% carex -0.17 -0.01 0.00 0.78 -0.02 

% eriophorum 0.07 -0.23 -0.42 -0.23 -0.61 

% salix -0.13 0.42 0.48 -0.44 -0.06 

% dryas 0.03 -0.51 0.55 -0.01 0.26 

% cassiope 0.14 -0.18 -0.45 -0.31 0.62 

% moss -0.10 0.63 -0.22 0.10 0.31 

% ledum 0.57 0.17 -0.01 0.17 -0.05 

% lichen 0.56 -0.08 0.04 0.10 0.17 

Eigenvalue 2.54 1.26 1.21 1.16 1.04 

37
Table 9. General linear models of nest site selection by King Eiders at the 1 m scale, with corresponding 

AICc, ΔAICc, , number of parameters (K), model weight (wi), and coefficient of determination (r

2

), 

Kuparuk, Alaska, 2003. Models are sorted by AICc and those included in the 99% confidence set (sum of 

wi =0.99) are shown. Model parameters include dry, dry salix, moist salix, carex meadow, and moist forb 

habitat types. 

Model K AICc ΔAICc wi r

2

Dry, Dry salix, Moist salix, Carex 

meadow, 5 53.56 0.00 0.48 0.44 

Dry, Moist salix, Carex meadow, 4 53.85 0.29 0.41 0.43 

Dry, Carex meadow 3 57.70 4.14 0.06 0.40 

Dry 2 58.05 4.49 0.05 0.40 

Dry, Dry salix, Moist salix, Carex 

meadow, Moist forb (Global) 6 66.89 13.33 0.00 0.44 

38
Table 10. Model-averaged parameter estimates (θ), standard errors, and 95% confidence intervals derived 

from the 99% confidence set of candidate models from the logistic regression analysis of King Eider nest 

sites and random unoccupied sites at the 1 m scale at Kuparuk, Alaska, 2003. See Table 8 for parameter 

definitions. 

Parameter θ SE 95% CI 

Dry -3.57 1.20 -6.26 to -0.89 

Dry Salix -0.11 0.20 -0.55 to 0.34 

Moist salix -0.62 0.34 -1.37 to 0.13 

Carex Meadow 0.13 0.38 -0.72 to 0.98 

39
Table 11. Summary of model selection results for the nest survival of King Eiders at two sites on the 

North Slope of Alaska, Teshekpuk and Kuparuk, in 2002 and 2003. Models are ranked by ascending 

ΔAICc; wi is the model weight and K is the number of parameters. Factors in the top models included 

year, site, island/mainland nest location, a linear time trend (T), a quadratic time trend (TT), and distance 

to the nearest conspecific (conspecific). 

Model Deviance K AICc ΔAICc wi

Ssite+island 507.73 3 513.82 0 0.51 

Ssite*T+island 506.23 5 516.45 2.63 0.14 

Ssite*TT+island 504.41 6 516.73 2.90 0.12 

Ssite*conspecific+island 506.63 5 516.85 3.03 0.11 

Ssite*conspecific 514.56 2 518.60 5.12 0.04 

Ssite*T*conspecific+island 505.13 7 519.56 5.73 0.03 

Table 12. Estimates of nest survival over a 27-day interval (23-day incubation + 4 day average laying 

period) from the best approximating model (Ssite+island) for King Eiders at Teshekpuk and Kuparuk, in 2002 

and 2003. 

 Mainland (Mean ± SE) Islands (Mean ± SE) 

Kuparuk 0.14 ± 0.05 0.36 ± 0.07 

Teshekpuk 0.04 ± 0.02 0.17 ± 0.48 

40