OCS Study MMS 2006-14 

Demographics and Behavior of Polar Bears Feeding on Bowhead Whale Carcasses at 

Barter and Cross Islands, Alaska, 

2002-2004 

Prepared for: 

U.S. Department of the Interior 

Minerals Management Service 

Alaska Outer Continental Shelf Region
Final Report 

Demographics and Behavior of Polar Bears Feeding on Bowhead Whale Carcasses at 

Barter and Cross Islands, Alaska, 

2002-2004 

by 

Susanne Miller, Scott Schliebe, and Kelly Proffitt 

U.S. Fish and Wildlife Service 

Marine Mammals Management 

1011 E. Tudor Road 

Anchorage, Alaska 99503 

April 2006 

This study was funded by the U.S. Department of the Interior, Minerals Management Service, 

Alaska Outer Continental Shelf Region, Anchorage, Alaska, under Intra-agency Agreement No. 

0102RU85166, NSL # AK-02-10, as part of the MMS Alaska Environmental Studies Program. 

The opinions, findings, conclusions, or recommendations expressed in this report or product are 

those of the authors and do not necessarily reflect the views of the U.S. Department of the 

Interior, nor does mention of trade names or commercial products constitute endorsement or 

recommendation for use by the Federal Government. 
Acknowledgements 

The authors wish to thank the Minerals Management Service for funding this study. Special 

appreciation is extended to the Nuiqsut Whaling Captains Association and the Arctic National 

Wildlife Refuge for providing accommodations and logistical support at Cross and Barter 

islands, respectively. 

We thank the following people who participated in data collection: Sherman Anderson (Alaska 

Nanuuq Commission); Anthony Fischbach and Steven Partridge (U.S. Geological Survey, 

Alaska Science Center); Jason Ransom (National Park Service, Denali National Park), Alan 

Brackney, Sara Gillespie, Steven Kendall, Jennifer Reed, Cashell Villa, Tara Wertz, and Gary 

Wheeler (U.S. Fish and Wildlife Service, Arctic National Wildlife Refuge); and Thomas Evans, 

Craig Perham, Jonathan Snyder, and James Wilder (U.S. Fish and Wildlife Service, Marine 

Mammals Management). We thank Steven Amstrup, George Durner, and Geoffrey York (U.S. 

Geological Survey, Alaska Science Center) for providing information on collared bears. Shaylin 

Howlin (West. Inc.) provided valuable review and guidance on study design. Jeffrey Bromaghin 

(U.S. Fish and Wildlife Service, Fisheries and Habitat Conservation), Thomas Evans, and 

Geoffrey York provided useful comments on the draft report. 

We are in gratitude to the residents of Kaktovik and Nuiqsut, the Alaska Nanuuq Commission, 

and the North Slope Borough Department of Wildlife Management for their support of this 

project. 
Table of Contents 

Introduction.......................................................................................... 1 

Background............................................................................................. 1 

Purpose.................................................................................................. 2 

Methods................................................................................................. 2 

Funding and Participants..............................................................................2 

Study Area.............................................................................................. 3 

Study Design............................................................................................ 6 

Sampling Methods..................................................................................... 6 

Results................................................................................................ 7 

Monitoring Effort....................................................................................... 7 

Number of Polar Bears at Barter and Cross Islands............................................... 8 

Age-Sex Composition.................................................................................10 

Behavior and Activity Patterns......................................................................12 

Habitat Use..............................................................................................19 

Movements and Interchange of Polar Bears Between Barter and Cross Islands..............19 

Discussion..............................................................................................21 

Demography of Polar Bears Using Barter and Cross Islands ....................................21 

Behavior................................................................................................22 

Use of Marine Habitat..................................................................................23 

Movements and Interchange..........................................................................23 

Management Applications and Future Research...................................................24 

Literature Cited.......................................................................................25 

Personal Communications and Unpublished Data.............................................27 

Appendix 1. Field Data Collection Definitions..................................................28 
List of Tables 

Table 1. Monitoring effort for polar bear feeding ecology study at Barter and Cross islands, 

Alaska, September/October, 2002-2004............................................................ 7 

Table 2. Estimated number of polar bears observed during “whole island” counts at Barter and 

Cross islands, Alaska, 2002-2004................................................................... 8 

Table 3. Estimated number of polar bears observed at study sites on Barter and Cross islands, 

Alaska, 2002-2004....................................................................................9 

Table 4. Estimated number of polar bears observed during day, dawn/dusk, and night at study 

sites, 2002-2004.......................................................................................9 

Table 5. Sighting and telemetry movement information for radio-collared bears observed at 

Barter Island, Alaska, 2002-2004. .................................................................20 

List of Figures 

Figure 1. Approximate boundary of the Beaufort Sea polar bear population (solid line) and core 

activity area (dotted line) as determined by harmonic mean analysis of satellite radio telemetry 

data collected during 1985-1993 (Amstrup 2000).......................................................................... 4 

Figure 2. General location of polar bear feeding ecology study area, Alaska, 2002-2003............. 4 

Figure 3. Polar bear feeding ecology study sites at Barter Island, Alaska, 2002-2004 .................. 5 

Figure 4. Polar bear feeding ecology study site at Cross Island, Alaska, 2002-2004..................... 5 

Figure 5. Proportion of polar bear age-sex classes observed at Barter and Cross islands, Alaska, 

2002-2004.....................................................................................................10 

Figure 6. Age-sex composition of polar bears observed at feeding sites on Barter and Cross 

islands, 2002-2004...........................................................................................11 

Figure 7. Behavior of polar bears observed on Barter and Cross islands, Alaska, 2002-2004....12 

Figure 8. Polar bear behavior compared by time period at Bernard Spit, Alaska 2002-2004......13 

Figure 9. Polar bear behavior compared by time period at the Barter Island feeding site, Alaska, 

2002-2004. .................................................................................................................................. 13 

Figure 10. Polar bear behavior compard by time period at Cross Island, Alaska, 2002-2004.....14 

Figure 11. Polar bear behavior compared by age/sex class at Bernard Spit, Alaska, 2002-2004..16 

Figure 12. Polar bear behavior compared by age/sex class at the Barter Island feeding site, 

Alaska, 2002-2004. ....................................................................................................................... 17 

Figure 13. Polar bear behavior compared by age-sex class at Cross Island, Alaska, 2002-2004..18 
1

Introduction 

Background 

In the southern Beaufort Sea region, polar bears feed primarily on ringed seals (Phoca hispida) 

and to a lesser extent on bearded seals (Erignathus barbatus) (Stirling and Archibald 1977, 

Smith 1980, Stirling 2002). Polar bears also feed on whale carcasses stranded along the Alaskan 

coastline during fall months (Craig George, unpublished data, Kalxdorff 1997). In 1999, the 

U.S. Fish and Wildlife Service (FWS) began flying aerial surveys along the Beaufort Sea 

coastline between Cape Halkett and Jago Spit near Barter Island (Figure 1) during the fall open 

water period (September-October) to determine the distribution and abundance of polar bears in 

the central Beaufort Sea coastal area. Results indicate that the majority (73%) of polar bears 

observed in 2000-2004 were located within 12 km of Barter Island, where unused portions of 

bowhead whales (Balaena mysticetus) were deposited by Kaktovik residents during fall whaling 

(14th Polar Bear Specialist Group [PBSG] proceedings, in prep.). Preliminary findings from a 

2003 polar bear diet study indicate that bowhead whales comprise part of some bears’ diets, 

based on the stable carbon and nitrogen isotopic composition found in red blood cells obtained 

from 49 free ranging polar bears (Bentzen et al. 2004). Availability of bowhead whale remains 

may be a contributing factor to polar bear abundance along coastal areas of the Beaufort Sea 

(14th PBSG proceedings, in prep, Traditional Ecological Knowledge provided by Kaktovik and 

Nuiqsut hunters for this study 2005, U.S. Fish and Wildlife Service 1986). 

Barter Island is located 145 km west of the Canadian border and within the Arctic National 

Wildlife Refuge (NWR). Barter Island has been used by Alaska Natives as a traditional 

gathering place for centuries; the contemporary community of Kaktovik was incorporated as a 

second class city in 1971. The population of Kaktovik was 293 residents in 2000, most of whom 

are Native (U.S. Census Bureau 2000). Bowhead whale hunting has been and continues to be an 

important part of the local culture and lifestyle (Jacobson and Wentworth 1982). Recent fall 

bowhead whale harvests were first recorded at Kaktovik in 1964; since 1989, two to four whales 

have been harvested annually (Koski et al. 2005). The majority (64%) of whales are taken 

between September 1 and 20 (Koski et al. 2005). In recent years, a significant trend towards 

earlier harvest has occurred, probably because of improved hunting techniques and equipment, 

and perhaps also because the size of the bowhead population is increasing, and whales may be 

more numerous near Kaktovik early in the hunting season (Koski et al. 2005). 

Cross Island, located approximately 20 km off shore from Prudhoe Bay, serves as the base for 

Inupiat whalers from Nuiqsut, a small village of approximately 433 residents (U.S. Census 

Bureau 2000) located approximately 25 km inland from the mouth of the Colville River. Cross 

Island has been used traditionally and more contemporarily as part of Nuiqsut hunters’ 

traditional subsistence harvest area (BLM 2005). Consistent annual use of Cross Island began 

around 1986, after a whaler’s agreement was signed between Nuiqsut residents and the oil and 

gas industry. Since then, zero to four whales have been harvested near Cross Island annually 

(North Slope Borough, unpublished data; M. Galginaitis, pers. comm.). The fall whaling season 

occurs between late August and early October, depending on ice and weather conditions (BLM 

2005). 
2

Whale remains may provide an additional source of nutrition to polar bears immediately prior to 

onset of winter, a critical time for polar bears, especially pregnant females. However, the 

potential of whale remains to attract large numbers of polar bears in close proximity to human 

settlements is of concern because of the likelihood of increased bear-human interactions. High 

densities of bears may also make animals more vulnerable to other perturbations such as 

exposure to contaminants and toxic wastes, and to an increased level of disease transmission. 

The near shore environment is subject to oil and gas development and other human activities that 

have the potential to impact polar bears and their foraging habits or activity patterns. Modeling 

estimates of oil potentially spilled from Outer Continental Shelf (OCS) developments would be 

improved if information regarding polar bear aggregations along the Beaufort Sea coast during 

fall months were considered. 

Purpose 

In 2002 the Minerals Management Service (MMS) provided funds to FWS to conduct a study of 

polar bears feeding on bowhead whale carcasses along the Beaufort Sea coast of Alaska. The 

primary purpose of this study was to increase understanding of foraging and carcass utilization 

by polar bears using the near shore environment. The resulting information has the potential to 

minimize disturbance to feeding bears from oil and gas development and other human activities. 

The specific objectives of this study were to: 

1) determine the demographics (number, age, and sex) of polar bears using Barter Island 

during fall months; 

2) determine the demographics of polar bears using Cross Island during fall months; 

3) determine polar bear behavior (activity patterns) and habitat use at Barter and Cross 

islands; and 

4) determine the magnitude of interchange of polar bears between Barter and Cross islands 

during fall months. 

This information is for use by MMS and other natural resource managers in environmental 

assessments for oil and gas lease sales, exploration and development projects, oil spill 

contingency planning, and future bear-human interactions. The information is consistent with 

and supports conservation of polar bears and their habitats, as mandated under the Marine 

Mammal Protection Act, and as set forth in the Habitat Conservation Strategy for Polar Bears in 

Alaska (U.S. Fish and Wildlife Service 1995). 

Methods 

Funding and Participants 

Funding was provided in 2002 for a two-year period; in 2003, a modification to the initial 

contract extended the duration of the study to allow for completion of a third year of field work 

in 2004. 

 
3

Polar bears evoke considerable public interest in their conservation and research. In Alaska, a 

number of entities and organizations both influence and/or are affected by conservation efforts. 

To facilitate coordination with these entities FWS worked cooperatively with the Alaska Nanuuq 

Commission (ANC), Alaska Eskimo Whaling Commission (AEWC), North Slope Borough 

(NSB), and the Native villages of Kaktovik and Nuiqsut prior to and during implementation of 

this study. The ANC, U.S. Geological Survey’s Alaska Science Center (USGS/ASC), and the 

Arctic NWR provided staff to participate in the study. The Arctic NWR provided 

accommodations at Barter Island. The Nuiqsut Whaling Captain’s Association provided advice, 

logistical support, and accommodations on Cross Island. The Native Villages of Kaktovik and 

Nuiqsut worked cooperatively with the FWS to implement a traditional ecological knowledge 

(TEK) study that provided historical background information on polar bear feeding at Barter and 

Cross islands. In addition, FWS scheduled annual visits to Kaktovik and Nuiqsut to provide 

status reports to local residents at public meetings, and to discuss progress of the study with city 

and tribal councils. 

Study Area 

The study area lies within the core activity area of the Southern Beaufort Sea population of polar 

bears (Amstrup 2000, Figure 1). Within this area, Barter and Cross islands were selected, based 

on prior knowledge of frequent polar bear seasonal habitat use and the reliable presence of 

bowhead whale remains (Figure 2). At Barter Island (Figure 3) two study sites were selected for 

monitoring, based on the distribution and activity patterns of bears, as determined by local 

knowledge and prior reconnaissance. The sites were: 1) Bernard Spit: a barrier island located 

between 70.08° N 143.36° W and 70.07° N 143.25° W, and a 100 m zone of marine habitat on 

the near shore (lagoon) side of this area (note that Bernard Spit is used by polar bears primarily 

for resting, thereby providing the opportunity to observe polar bears at a “non-feeding” site); and 

2) Barter Island feeding site (“bone pile”): located approximately 2 km east of the village of 

Kaktovik. It includes a spit of land on which the bone pile is located, and a 100 m zone of 

marine habitat surrounding this area. Bernard Spit and the feeding site are separated by Bernard 

Harbor, a distance of 1-2 km. 

Cross Island (Figure 4) is a small (5 km), crescent-shaped barrier island located approximately 

20 km off shore from Prudhoe Bay at 70.30° N 147.55° W and is used seasonally by polar bears 

for both resting and feeding. The Cross Island feeding site includes the bone pile, jawbones, and 

a 300 m zone around these areas. 
4

Figure 1. Approximate boundary of the Beaufort Sea polar bear population (solid line) and core 

activity area (dotted line) as determined by harmonic mean analysis of satellite radio telemetry 

data collected during 1985-1993 (Amstrup 2000). 

Figure 2. General location of polar bear feeding ecology study area, Alaska, 2002-2004. 
5

 Figure 3. Polar bear feeding ecology study sites at Barter Island, Alaska, 2002-2004. 

 Figure 4. Polar bear feeding ecology study site at Cross Island, Alaska, 2002-2004. 
6

Study Design 

Methods involved conducting direct observations of polar bears at the three study sites during the 

fall open water period between early September and the first week of October. Each 24-hour 

period was divided into eight 3-hour sessions (= sample units), based on available daylight: 1) 

dawn (6:00-9:00 h); 2) day (9:00-18:00 h) 3) dusk (18:00-21:00 h); or 4) night (21:00-6:00 h). 

We systematically sampled four sessions every 24 hours (weather permitting) per island. 

Bernard Spit could not be sampled at night, due to a combination of large viewing distances and 

insufficient light. 

At Barter Island, observations were conducted from a pick-up truck by two people using Leica 

Televid 77 spotting scopes and Leitz 10 x 42 binoculars. At Cross Island, observations were 

conducted from the roof of a whaling cabin by one person using a Leica Televid 77 spotting 

scope and Smith and Wesson Startron Starlight night vision optics. Observation distances 

ranged from 10-1000 m. 

Sampling Methods 

A combination of focal and scan sampling methods were used (Altman 1974, Tacha et al. 1985). 

Scan sampling data were recorded on data sheets and later entered into a Microsoft Access 

database. Focal sampling data were recorded using a palmtop computer and The Observer 

software (Noldus Technology, Leesburg, VA). 

Scan Sampling (Study Site Counts). Scan sampling recorded the number, age, and sex of all 

polar bears observed at the study sites at 15-minute intervals (or 30-minute intervals when large 

numbers of bears necessitated a longer count interval). Age/sex classes of polar bears were 

determined based on the size of the animal, number of dependents, presence of collars, and other 

distinguishing factors, e.g. scars, markings, body size and shape, presence of penile hairs. 

Animals bearing distinguishing marks (e.g. a collar) were assigned an individual identification 

number and their presence was noted during each scan; whenever possible, their arrival and 

departure times were also recorded. Dependent cubs were included in all counts. 

During analysis, data (number, age, and sex of bears) from all scans that occurred within a threehour session were combined and divided by the total number of scans to derive one sample unit 

per session (= average number of bears per scan). This approach was taken to avoid problems 

associated with auto-correlation (same bears showing up repeatedly at adjacent 15-minute scans). 

Sample units were then combined by year, location, and time period. These data were used to 

derive Study Site Counts and Age/Sex Composition data in the Results section. 

Focal Sampling. Focal sampling recorded the behavior and habitat use of randomly-selected 

polar bears during 20-minute intervals. If the animal disappeared from view for more than five 

minutes, a new focal animal was selected. Animals that were observed for less than ten minutes 

before they became unobservable were not included in study results. The total number of 

minutes engaged in specific behaviors and habitat type was combined by year, location, and time 

period for analysis. Bear behavior and habitat types are defined in Appendix 1. 
7

Whole Island Counts. In addition to sampling effort at the study sites, we obtained daily counts 

of the number of polar bears visible at Barter and Cross islands. At Barter Island, this included 

all observable terrestrial areas, (including the two study sites), Kaktovik Lagoon, Bernard 

Harbor, and Drum Island. At Cross Island, whole island counts included numbers of animals 

that were present anywhere on the island, including the feeding site. Dependent cubs were 

included in all counts. 

TEK. Representatives from the Native Villages of Kaktovik and Nuiqsut (tribal councils) 

conducted meetings with ten residents (seven from Kaktovik, three from Nuiqsut) to discuss 

historical use of bowhead whale carcasses. Their observations were recorded on data collection 

forms and later summarized by village; some of the information was included in this report. 

The following assumptions are inherent to the study plan: 1) sampling protocols adequately 

document patterns of use with respect to time during the study period; and 2) observers are 

capable of categorizing bears into appropriate age/sex classes, recognizing that some animals 

cannot be classified to age or sex due to a lack of distinguishing physical features, or to restricted 

visibility. 

Results 

Monitoring Effort 

The study period occurred annually between September 3 and October 4, 2002-2004 (Table 1). 

A total of 1,230 hours of observations were conducted, including 4,733 scans and 926 focal 

samples. Overall, monitoring effort was allocated as follows: 44% at the Barter Island feeding 

site; 40% at Cross Island, and 16% at Bernard Spit. 

Table 1. Monitoring effort for polar bear feeding ecology study at Barter and Cross islands, 

Alaska, September/October, 2002-2004. 

Barter Island Cross Island 

2002 2003 2004 2002 2003 2004 

Study 

Period 

Sep. 3-29 Sep. 8-

Oct. 3 

Sep. 9-

Oct. 4 

Sep. 10-25 Sep. 15-27 Sep. 16-27

# Hours 

Monitored 

209 247 277 184 170 144 

# Scan 

Samples 

739 831 1085 770 714 594 

# Focal 

Samples 

213 229 290 23 38 133 
8

Number of Polar Bears at Barter and Cross Islands 

Whole Island Counts. We observed a range of 0-65 bears within the Barter Island study area, 

with a 3-year mean of 33.1 (SD= 15.5) bears. At the Cross Island study area, we observed a 

range of 0-13 bears with a 3-year mean of 6.1 (SD=3.8) bears (Table 2). 

 

Table 2. Estimated number of polar bears observed during “whole island” counts at Barter and 

Cross islands, Alaska, 2002-2004. 

Barter Island Cross Island 

2002 2003 2004 2002 2003 2004 

Study Period Sept. 3-29 Sept. 8- 

Oct. 3 

Sept. 9- 

Oct. 4 

Sept. 

10-25 

Sept. 15-27 Sept. 16-27 

# of Counts 22 33 28 16 13 50 

Minimum # of 

Bears 

0 3 22 0 1 4 

Maximum # of 

Bears 

51 61 65 7 7 13 

Mean # of Bears 22.8 33.6 40.6 1.5 3 8.4 

Standard 

Deviation (SD) 

17.7 14.3 9.7 2 2 2.3 

3-Year Mean ± 

SD 

33.1 ± 15.5 6.1 ± 3.8 

 

Study Site Counts. At Bernard Spit, we observed a range of 3-61 bears with a 3-year mean of 

27.7 (SD= 10.1) bears. At the Barter Island feeding site, we observed a range of 0-37 bears with 

a 3-year mean of 4.9 (SD= 4.9) bears. At Cross Island, we observed a range of 0-12 bears with a 

3-year mean of 2.8 (SD = 2.7) bears. The minimum, maximum and mean number of polar bears 

observed annually at the selected study sites is described in Table 3. 
9

Table 3. Estimated number of polar bears observed at study sites on Barter and Cross islands, 

Alaska, 2002-2004. 

Bernard Spit Barter Island Feeding 

Site 

Cross Island Feeding 

Site 

2002 2003 2004 2002 2003 2004 2002 2003 2004 

Study Period Sep. 

3-29 

Sep. 8 

Oct. 3 

Sep. 9 

Oct. 4 

Sep. 

10-25 

Sep. 

15-27 

Sep. 

16-27 

Sep. 

11-25 

Sep. 

15-27 

Sep. 

16-27 

# of Scans 84 191 201 655 640 884 463 516 553 

Minimum # 

Bears 

3 10 9 0 0 0 0 0 0 

Maximum # 

Bears 

44 61 48 37 29 34 4 6 12 

Mean # Bears 25.4 31.8 25.1 6.2 4.7 4.1 0.5 1.6 5.6 

Standard 

Deviation (SD) 

10.9 10.2 7.5 5.3 5.2 4.0 0.8 1.3 2.1 

3-Year Mean ± 

SD 

27.7 ± 10.1 4.9 ± 4.9 2.8 ± 2.7 

We analyzed data by time period to determine whether time of day had an effect on bear 

numbers present at the feeding sites (Table 4). At Barter Island, the highest period of use was at 

“night” at the feeding site with an average of 8 polar bears per scan, compared to 3 and < 1 polar 

bears/scan during “dawn/dusk” and “day” periods respectively. During the “day” period, most 

polar bears had moved from the feeding site to off-shore areas such as Bernard Spit and Drum 

Island. An average of 30 polar bears/scan were observed at Bernard Spit during the day, 

compared to 25 during dawn/dusk when bears were more active (see also Behavior section). 

Night use of Bernard Spit is unknown since the area was not visible to observers. At Cross 

Island, bear use of the feeding site was similar during “day” and “dawn/dusk” time periods with 

an average of 3 polar bears per scan. No reliable estimates were obtained for the “night” period 

because of restricted visibility, despite the use of night-vision optics. We know polar bears were 

active at night as evidenced by numerous bears encountered in close proximity to our 

observation post; however, we were unable to quantify the extent to which they were present at 

the feeding site. 

Table 4. Estimated number of polar bears observed during day, dawn/dusk, and night at study 

sites, 2002-2004. 

 Bernard Spit BTI Feeding Site Cross Island 

Time Period Mean SD Mean SD Mean SD 

Day 29.5 10.2 0.9 1.4 3.1 2.8 

Dawn/Dusk 25.3 9.6 3.3 2.4 2.5 2.6 

Night --- --- 8.3 5.0 --- --- 
10

Brown Bears. Of special interest was the presence of 8-12 brown bears (Ursus arctos) at the 

Barter Island feeding site in 2003 and 2004. While polar and brown bears have been observed 

interacting at the Prudhoe Bay dump (Richard Shideler and Scott Schliebe, pers. comm.), to our 

knowledge, these are the first recorded incidents of polar and brown bears interacting at bowhead 

whale carcasses in Alaska. Additional information on interactions between the two species will 

be collected at Barter Island in 2005. 

Age-Sex Composition 

All age-sex classes of polar bears were observed at both Barter and Cross islands during the 

study period (Figure 5). At the Barter Island feeding site, 47% of the bears observed during the 

three-year period were comprised of family groups (17% mothers, 30% dependent cubs); 35% 

were single bears (24% adults, 11% sub-adults); and 18% were bears of unknown age or gender. 

At Cross Island, 27% of the bears observed were comprised of family groups (12% mothers, 

15% cubs); 66% were single bears (63% adults, 3% sub-adults), and 7% were bears of unknown 

age or gender. 

Figure 5. Proportion of polar bear age-sex classes observed at Barter and Cross islands, Alaska, 

2002-2004. 

12

15

63

3

7

0

10

20

30

40

50

60

70

% Family 

Groups

% Single 

Bears 

% Unknowns

Cross Island

Unknowns

Sub-Adults

Adults

Cubs

Mothers

17

30

24

11

18

0

10

20

30

40

50

% Family

Groups

% Single

Bears

%Unknowns

Barter Island

Unknowns

Sub-Adults

Adults

Cubs

Mothers
11

We analyzed data by time period to determine whether time of day had an effect on age-sex 

composition of polar bears at the feeding sites. Age-sex data for Bernard Spit and Cross Island 

at night were excluded from analyses since extensive viewing distances prevented accurate aging 

and sexing of animals and resulted in a high proportion of animals being classified as unknowns 

(= bears of unknown age and gender). At Barter Island, the proportion of family groups and subadults was greatest during “day” and “dawn/dusk” time periods, whereas the proportion of single 

adults was greatest during “night” time periods (Figure 6). Similarly, at Cross Island the 

proportion of family groups using the feeding site was greater during the “day” time period, 

whereas the proportion of single adults was greater during the “dawn/dusk” time period. 

Figure 6. Age-sex composition of polar bears observed at feeding sites on Barter and Cross 

islands compared by time period, 2002-2004. 

Polar Bear Composition by Time Period at Barter

Island

24

20

13

38 37

21

12

20

32

12 14

9

14

9

25

0

10

20

30

40

Day Dawn/Dusk Night

% Mothers

% Cubs

% Single Adults

% Sub-adults

% Unknowns

Polar Bear Composition by Time Period at Cross

Island

15 10

18 13

57

66

4 3 6 8

0

20

40

60

80

Day Dawn/Dusk

% Mothers

% Cubs

% Single Adults

% Sub-adults

% Unknowns
12

Behavior and Activity Patterns 

Figure 7 depicts behavior exhibited by polar bears at the study sites during 2002-2004. 

Behaviors that constituted less than 1% of the total time were excluded from results; night data 

for Cross Island was also excluded from results. A total of 17,670 minutes collected during 911 

focal samples were used for these analyses. The predominant behavior at Bernard Spit and Cross 

Island was laying (69% and 60% respectively); at the Barter Island feeding site the predominant 

activity was feeding (64%). 

 

Figure 7. Behavior of polar bears observed on Barter and Cross islands, Alaska, 2002-2004. FI 

= family interactions among mothers and dependent cubs; NFI = non-family interactions. 

Bernard Spit

Swimming

1%

Sitting

6%

Laying

69%

Feeding

4%

NFI

2%

FI

2%

Walking

11%

Standing

5%

Barter Island Feeding Site

Standing

6% Walking

12%

NFI

2%

Feeding

64%

Laying

6%

Unobservable

4%

Sitting

2%

Swimming

4%

Cross Island 

Swimming 

1%

Sitting

3% 

Laying 

60%

Unobservable

4%

Feeding

15%

NFI

1%

Walking

11%

Standing

5%

n = 228 samples 

(4,524 min.) 

n = 504 samples 

(9,630 min.) 

n = 179 samples 

(3,516 min.) 
13

When specific behaviors were compared by time period, (Figures 8-10), bears at all study sites 

during the “day” time periods were predominantly inactive (laying, sitting, or standing) and 

allocated the least amount of time feeding compared with other time periods. Non-family 

interactions and walking behaviors were greater during “dawn/dusk” time periods compared to 

“day” time periods at all study sites. Non-family interactions during “night” time periods were 

also greater than during the “day” time period at the Barter Island feeding site. 

 

 Figure 8. Polar bear behavior compared by time period at Bernard Spit, Alaska 2002-2004. 

Dawn = 6:00-9:00h; Day = 9:00-18:00h; Dusk = 18:00-21:00h; Night = 21:00-03=06:00h). FI = 

family interactions among mothers and dependent cubs; NFI = non-family interactions. 

Day: Bernard Spit

Laying

77% 

Sitting

5% 

Swimming 

1% 

Standing

4%

FI

2%

Feeding

3%

NFI

1%

Walking

7%

Dawn/Dusk: Bernard Spit

Swimming

2% Other

1%

Sitting

9%

Laying

53%

Feeding

7%

Unobservable 

1%

NFI

3% FI

2%

Walking

15%

Standing

7%

n = 144 samples 

(2,861 min.) 

n = 84 samples 

(1,663 min.) 
14

Day: Barter Island Feeding Site 2002-2004

Swimming

Sitting 6%

7%

Laying

10%

Unobservable

2%

Feeding

55%

Running

1%

FI

1%

Walking

9%

Standing

9%

 

Dawn/Dusk: Barter Island Feeding Site 2002-

2004 

Swiming

4% Sitting

1%

Unobservable

3%

Laying

4%

Feeding

64%

NFI

2%

FI

1%

Walking

14%

Standing

7%

Night: Barter Island Feeding Site 2002-2004

Swimming

4%

Sitting

1% Laying

7%

Unobservable

5%

Feeding

64%

NFI

2%

Walking

11%

Standing

6%

Figure 9. Polar bear behavior compared by time period at the Barter Island feeding site, Alaska, 2002-

2004. Dawn = 6:00-9:00h; Day = 9:00-18:00h; Dusk = 18:00-21:00h; Night = 21:00-03=06:00h). FI = 

family interactions among mothers and dependent cubs; NFI = non-family interactions. 

n = 54 samples 

(1,049 min.) 

n = 157 samples 

(3,051 min.) 

N = 292 samples 

(5,530 min.) 
15

 

 Figure 10. Polar bear behavior compared by time period at Cross Island, Alaska, 2002-2004. 

Dawn = 6:00-9:00h; Day = 9:00-18:00h; Dusk = 18:00-21:00h; Night = 21:00-03=06:00h). FI = 

family interactions among mothers and dependent cubs; NFI = non-family interactions. 

When specific behaviors were compared by age-sex class (Figures11-13), some differences were 

noted among cohorts. At Bernard Spit, sub-adult bears spent a greater proportion of time 

walking, feeding, and engaged in non-family interactions than single adult bears or mothers with 

cubs. At the Barter Island feeding site, single adult bears spent a greater proportion of time 

feeding; sub-adult bears spent a greater proportion of time walking; females accompanied by 

cubs spent a greater proportion of time engaged in standing, sitting, laying, and swimming 

behaviors than each of their respective cohorts. 

Dawn/Dusk: Cross Island

Rolling

1%

Sitting

2%

Swimming

1%

Laying

49%

Unobservable

5%

Feeding

23%

Walking

12%

NFI

1%

Standing

6%

Day: Cross Island 

Standing

5%

Swimming

2%

Sitting

3%

Laying

71%

Unobservable

3%

Feeding

7%

Walking

9%

n = 93 samples 

(1,715 min.) 

n = 86 samples 

(1,801 min.) 
16

Bernard Spit: Females with Cubs

Swimming

1%

Other

1%

Sitting

7%

Laying

67%

Feeding

3%

FI 

4%

Walking

9%

NFI

1%

Standing

7%

 

 Figure 11. Polar bear behavior compared by age/sex class at Bernard Spit, Alaska, 2002-2004. 

 FI = family interactions among mothers and dependent cubs; NFI = non-family interactions. 

Bernard Spit: Single Adults

Swimming

2%

Sitting

8%

Laying

70%

NFI

1%

Feeding

4%

Standing

4% Walking

11%

Bernard Spit: Sub-Adults

Swimming

6%

Sitting

9%

Laying

44%

Feeding

10%

NFI

10%

Walking

15%

Standing

6%

n = 105 samples 

(2,085 min.) 

n = 71 samples 

(1,413 min.) 

n = 16 samples 

(1,413 min.) 
17

 

Figure 12. Polar bear behavior compared by age/sex class at the Barter Island feeding site, Alaska, 

2002-2004. FI = family interactions among mothers and dependent cubs; NFI = non-family 

interactions. 

Females with Cubs 2002-2004

Swimming

6%

Sitting

3%

Laying

9%

Unobservable

3%

Feeding

57%

Running

1% NFI

1%

FI

1%

Walking

11%

Standing

8%

Single Adults 2002-2004

Feeding

72%

Standing

5%

Unobservable

4%

Laying

5%

Sitting

1%

NFI

2%

Swimming

1%

Walking

10%

Sub-Adults 2002-2004

Sitting

1%

Swimming

2%

Unobservable

5%

Feeding

66%

NFI

3%

Walking

17%

Standing

6%

n = 194 samples 

(3,763 min) 

n = 176 samples 

(3,403 min.) 

n = 79 samples 

(1,475 min.) 
18

At Cross Island, single adults spent the greatest proportion of time laying and the least proportion of 

time walking; conversely, sub-adults spent the least proportion of time laying and the greatest 

proportion of time walking and feeding. Females with dependent cubs also spent a greater 

proportion of time walking than single adults, and a slightly greater proportion of time swimming 

than either single adult or sub-adult bears. 

Females with Cubs

Swimming

4%

Sitting

2%

Standing

8%

Walking

15%

FI

1%

Feeding

16%

Unobservable

1%

Laying

53%

Adults

Standing

4%

Unobservable

5%

Feeding

15%

Laying

62%

Sitting

3%

Swimming

1%

Rolling

1% Walking

8%

NFI

1%

Sub-Adults

Sitting

4%

Laying

30%

Unobservable

8% Feeding

34%

Walking

18%

Standing

6%

 Figure 13. Polar bear behavior compared by age-sex class at Cross Island, Alaska, 2002-2004. 

FI = family interactions among mothers and dependent cubs; NFI = non-family interactions. 

n = 46 samples 

(920 min.) 

n = 101 samples 

(1,960 min.) 

n = 13 samples 

(235 min.) 
19

Habitat Use 

Habitat types used by polar bears during this study were classified as: mainland (Barter Island 

feeding site); barrier island (Bernard Spit and Cross Island); and marine habitat (marine portions 

of study sites). In all years the study period ended prior to freeze-up (= formation of ice adjacent 

to shore); therefore, no use of ice habitat was recorded. Although marine habitat was underrepresented as a habitat type at our study sites, we recorded the frequency of its use (as the 

number of times bears entered water during focal sampling) in an effort to provide information 

useful in assessing the potential risk of polar bears contacting oil in the marine environment in 

event of a fuel spill. The question posed was: once polar bears arrive on the coastline during 

the fall open water period, do they stay exclusively on land until freeze-up? Our data indicate 

that polar bears did not stay exclusively on land; rather, they made use of the marine 

environment after they arrived at our study sites. At Barter Island, most polar bears accessed and 

departed from the feeding site by swimming and, based on observations of individually 

recognizable bears, we believe that most polar bears were using the feeding sites every 1-2 days, 

although the duration of their stay at the study sites varied (see also Movements/Interchange

section). In addition to arrival and departure, bears at the Barter Island feeding site were 

observed using marine habitat in 23% (114/504) of focal animal samples and 6% (14/228) of 

focal animal samples at Bernard Spit. 

Marine use at Cross Island was less frequent, probably because once polar bears are on the 

island, they can access the feeding site from anywhere on the island without having to enter 

marine habitat each time they want to feed. This is due to the availability of undisturbed resting 

areas adjacent to the feeding site at Cross Island, and lack of alternative barrier island habitat 

nearby. Bear use of marine habitat was documented during 4% (7/194) of focal animal samples 

at Cross Island. In addition to swimming, we observed polar bears walking, standing, 

interacting, playing (with objects), cleaning fur, and carrying and eating muktuk (small pieces of 

whale skin with blubber attached) while in marine waters. Females with dependent cubs were 

the cohort most frequently observed in marine waters at all study sites. 

Movements and Interchange of Polar Bears between Barter and Cross Islands 

Duration of Residency at Study Sites. We recorded the number of days that individually 

recognizable polar bears were present at the study sites to determine whether polar bears 

remained present throughout the study period. Our data suggests that the duration of temporary 

residency within the immediate area varies by individual. Since we did not monitor the feeding 

site continuously, it is possible that polar bears fed while we were not present to observe them, 

and thus remained resident to the area without our knowledge. Table 5 provides sighting and 

movement information for five individually recognizable polar bears observed in 2002 at Barter 

Island. These data indicate that some polar bears stay for longer periods, while others may pass 

through the area more quickly. This variability in duration of residency was also observed at 

Cross Island. In 2002 and 2003, most polar bears remained on the island for short periods (< 24 

h). In 2004, several large males and at least one family group stayed the entire (two-week) study 

period, yet another family group left after approximately one week. 
20

Table 5. Sighting and telemetry movement information for radio-collared bears observed at Barter 

Island, Alaska, 2002-2004. ASC = U.S. Geological Survey, Alaska Science Center (responsible for 

polar bear research and collaring activities). COY= cub of the year (<1 year old). 

ASC Bear 

ID 

Life History Dates Observed 

at Barter Island 

 Notes 

20564 Adult female, age unknown; 

accompanied by 2 COYs in 

2002 

September 7-25, 

2002 

2002: observed at feeding site every 1-2 

days. 

Telemetry: moved west and then off 

shore in December 2002. Not known to 

have used Cross Island. No data 

available for 2003-2004. 

20465 Mature adult female born in 

1983; observed with no 

dependent cubs in 2002 

September 8-14, 

2002 

2002: one observed visit to feeding site 

in 2002. 

Telemetry: no telemetry data in 2002-

2003; radio locations obtained near 

Barter Island in May 2004. Not known 

to have used Cross Island. 

20413 Young adult female born in 

1997; observed with no 

dependent cubs in 2002 

September 9-19, 

2002 

2002: visited feeding site on at least 2 

occasions. 

Telemetry: data suggests that home 

range was in near-shore area in 2002. 

Located on Cross Island in December 

2002. No data available for 2003-2004. 

20419 Mature adult female born in 

1990; accompanied by 3 

COYs in 2002 and 3 

yearlings in 2003. 

September 18-28, 

2002 and 

September 9 - 

October 3, 2003 

2002: 1 COY smaller than the other two. 

Visited feeding site every 1-2 days. 

2003: 3 yearlings present; visited 

feeding site every 1-2 days. 

Telemetry: collar removed in spring 

2004. Not known to have used Cross 

Island. 

1737 Mature adult female born in 

1970; observed with no 

dependent cubs in 2002. 

September 28, 

2002 (last full day 

of study period) 

2002: appeared to be in poor condition 

and was present at the feeding site for at 

least 15 hours; departure of observers 

precluded further quantification of her 

length of stay. 

Telemetry: located annually within 10 

km of Barter Island feeding site in 1989-

1992. Located on Cross Island in 

December 2002/January 2003. 

Interchange of Bears between Barter and Cross Islands. To determine whether polar bears 

observed at Barter Island also use Cross Island, individually recognizable animals must be 

followed over time. Research biologists in Alaska routinely capture and outfit polar bears from 

the southern Beaufort Sea population with satellite radio-collars to track their movements and 

collect information regarding other aspects of their life history. During the study period we 

observed ten radio-collared females at our study sites; of these, five had actively transmitting 

collars and were therefore recognizable as individuals. All five of these bears were observed in 
21

2002 at Barter Island (see Table 5). No radio-collared bears were observed at Cross Island 

during 2002; thus collared bears observed at Barter Island did not travel to Cross Island during 

the study period. Similarly, no collared bears were observed on Cross Island in 2003; one 

collared adult female with 2 COYs was observed on Cross Island in 2004 but her collar was 

inactive, so we were unable to determine her identity. The distance between Cross and Barter 

islands is approximately 215 km; the 2-week duration of the study period at Cross Island in 

combination with the presence of a vast amount of open water during the study period probably 

limits the possibility of re-sighting individuals at both sites. Anecdotal information from aerial 

flights and observations of industry personnel working in the Cross Island area leads us to 

believe that the chronology of use of Cross Island may be later in the year. We reviewed satellite 

location information provided by USGS/ASC (unpublished data) to determine whether polar 

bears moved between the islands later in the season. These data suggest that polar bear 

movement between the two islands can occur after freeze-up, as illustrated by bear ID #1737 and 

20413 (Table 5). 

Intra-Annual Use of Study Sites. Another question posed to FWS was: are the same polar bears 

returning to the feeding site during subsequent years? Again, results are based on information 

related to radio-collared bears provided by USGS/ASC. Of the five collared bears that we 

observed at Barter Island, we know that at least one family group (ASC bear id 20419) visited 

Barter Island in subsequent years (2002 and 2003) during the open water season. The ASC 

captured this bear in the spring of 2004 and removed her collar; therefore, it is unknown whether 

she returned to Barter Island during 2004. 

Discussion 

Demography of Polar Bears Using Barter and Cross Islands 

Number of Polar Bears. Polar bears are believed to be relatively solitary animals unless in 

family groups, during mating season, or when food sources are concentrated in small areas, such 

as along leads. In Alaska, some polar bears come to shore during fall months and an increasing 

trend of use of coastal habitat during the fall open-water period is occurring. Traditional 

knowledge provided by Kaktovik and Nuiqsut hunters and elders indicates that bear distribution 

and abundance along the coast is closely related to ice conditions, and that distance of ice from 

shore affects the numbers of polar bear using the coastline. In 2005, Schliebe et al. (14th PBSG 

proceedings, in prep.) performed a regression analysis on the relationship between the number of 

polar bears on shore and distance from shore to the ice pack. They found that, as distance to ice 

increased, the number of bears increased; conversely, as ice advanced near-shore, the number of 

bears decreased. Durner et al. (2004) found that several factors, such as the extent of ice cover, 

ocean depth, and ice form and stage were important in habitat selection by polar bears, and that 

habitat selection is likely driven by prey availability and accessibility, as well as the availability 

of safe resting places. 

The factors that determine whether a polar bear will remain on sea ice or come to shore during 

late summer or fall are complex and may also be changing over time. We know that between 
22

2000 and 2004 the majority of polar bears observed along the coast during the fall open water 

period occurred within 12 km of Barter Island (14th PBSG proceedings, in prep.). Results from 

this study further confirm that polar bears tend to aggregate on Barter and Cross islands during 

the fall open water period, with greater bear numbers observed at Barter Island than at Cross 

Island. While bowhead whale remains may not be the primary reason why polar bears come to 

shore, these attractants likely play a role in concentrating polar bears that are using coastal areas 

during fall months. 

The feeding sites were used by a mean of 4.9 and 2.8 polar bears per scan at Barter and Cross 

islands, respectively, during the given study periods (see Table 3). At Cross Island, the mean 

number of bears using the feeding site increased over the 3-year period, as did numbers of bears 

using the entire island. However, at Barter Island, the mean number of bears using the bone pile 

was highest in 2002 and decreased in subsequent years, despite higher numbers of bears in the 

area. This indicates that local factors such as the quantity of whale remains may influence bear 

use of the feeding sites. For example, in 2002, Kaktovik whalers struck and lost a whale that 

was later recovered, but at that point, much of the whale was not suitable for human 

consumption, and the unused portions were placed at the bone pile. Other factors that may 

account for fewer bears using the bone pile in 2003 and 2004 include the social dynamics among 

polar bears, brown bears, and humans. For example, we frequently observed the presence of 

brown bears displacing polar bears from the feeding site. Further research to quantify such 

interactions is currently underway. 

Another factor that may affect numbers of polar bears using whale remains at Barter and Cross 

islands is time of day. At Barter Island, bear numbers were greatest at night and less during day. 

Cross Island night observations were not quantified but anecdotal observations of bears moving 

around the island (not always within our defined study area), as well as frequent encounters with 

polar bears at the viewing platform, indicate that activity is greater at night on Cross Island as 

well. 

Age-Sex Composition. All age-sex classes were observed at Barter and Cross islands; a greater 

proportion of bears were in family groups at Barter Island, whereas a greater proportion of bears 

were single adults at Cross Island. Age-sex composition data should be interpreted with caution 

because of the classification of a significant number of “unknown” age-sex animals that, if 

classified to sex or age, might affect cohort proportions. 

We did not expect to see many large adult males at the feeding sites since they have the ability to 

displace other sex/age classes from preferred feeding habitats out on sea ice. This is further 

evidenced by an under-representation of adult males in the harvest (Scott Schliebe, pers. comm.). 

Adult males were observed every year at both Barter and Cross islands during this study. Their 

presence along the coast might be related to ice conditions, declining seal availability, presence 

of attractants on shore, or other factors. This subject warrants further investigation. 

Behavior. Polar bears generally became more active with the onset of darkness. Study results 

from Barter Island indicate that polar bears actively feed most frequently at night; since we did 

not observe all “day” bears at the feeding site at night, some bears must either remain on Bernard 
23

Spit or similar habitat; visit the feeding site when we are not monitoring it, or leave the area. 

The increase in non-family bear-bear interactions during “dusk/dawn” at Bernard Spit and Cross 

Island, and at “night” at the Barter Island feeding site may be related to increased bear densities 

and activity levels. Given the high number of bears in a relatively small radius area near the 

feeding sites, surprisingly few aggressive interactions were observed. All age/sex classes of 

polar bears were often observed feeding simultaneously in close proximity of each other, 

including large adult males feeding right next to females with dependent cubs. While some 

bears, particularly females with COYs, seemed to become agitated or even displaced by the 

presence of other bears, overall, most polar bears seemed to tolerate each other. We also 

frequently observed large males resting in close proximity of each other, as well as arriving at 

and departing from the feeding sites together. Aggressive interactions among all polar bears 

tended to be short in duration and initiated by mothers or curious cubs. More intra-specific 

aggression may occur if the food supply were more limited. When brown bears were present, 

they tended to be dominant over polar bears and sometimes displaced polar bears from the 

feeding site. Nevertheless, simultaneous use of a feeding site by both polar and brown bears is a 

unique phenomenon and will be investigated further in the future. 

Females with cubs spent less time feeding and more time laying, sitting, or standing in what 

might constitute vigilant behavior (Dyck and Baydack 2004). The protective nature of individual 

females may motivate them to avoid other cohorts, e.g. use the feeding sites during times of low 

bear density (day). However, frequent day visits to the feeding sites may simply be a result of 

cubs’ higher energy demands needed for growth. 

Use of Marine Habitat 

Use of the Barter Island feeding site requires polar bears to enter marine waters to access and 

depart the site, unless they approach from the mainland, which was rarely observed. In addition 

to accessing the bone pile at Barter Island, polar bears also used marine waters for swimming 

and interacting. Family groups in particular spent more time in the water than other cohorts. 

Movements and Interchange 

Limited data from this study indicate that individual variability exists as to how long polar bears 

remain in the vicinity of the feeding sites. Some polar bears remained on site at both Barter and 

Cross islands for weeks at a time, and perhaps until freeze-up, whereas others remained only a 

few days. Duration of residence may be affected by environmental factors as well as by 

interactions with other bears and humans. No observations of polar bears using both Barter and 

Cross islands during our study periods were observed; however, telemetry data indicates that 

some interchange between the two islands can occur later in the season. 

Whether or not the same bears use these feeding sites in subsequent years is also a subject for 

future study. Mauritzen (1999) found that female polar bears in the Norwegian Arctic exhibit 

some seasonal fidelity to certain habitat types, and that area fidelity was greater for near-shore 

individuals than for pelagic individuals. In Alaska, Amstrup et al. (2000) reported that, although 
24

activity areas for bears in the southern Beaufort Sea are large and variable, most included a “core 

area” of overlap each year. Of polar bears captured near Kaktovik during 1985-1994, 46% were 

re-observed there (Amstrup et al 2000). Other studies (Shideler and Wendling 2005) of brown 

bears on the North Slope report that many of the bears feeding at alternative food sources e.g. 

dumps, are the offspring of mothers that fed there as well. In fact, Shideler and Wendling (2005) 

found that all food-conditioned bears in the Prudhoe Bay oilfield area were related to one of two 

maternal “clans”, one of which included three generations of bears that became conditioned to 

human food sources. All food-conditioned cubs (for which fate was known) became foodconditioned while with their mothers. Given these factors, there is a high probability that the 

number of polar bears, particularly at Barter Island, will increase in future years. 

Management Applications and Future Research 

Effective management of polar bears around human settlements requires knowledge of the 

number and age/sex classes of polar bears present, or likely to be present, over time. Results 

from this study are being used to monitor long-term trends of polar bear use of the Beaufort Sea 

coastline and for planning human activities such as oil and gas lease sales. In the future, 

however, scientists will need to better understand why polar bear use of coastal habitat is 

increasing, and more precisely what the role of alternative food sources such as marine mammal 

carcasses play in that trend. Previous studies indicate that polar bears can adapt to seasonal 

variation in ice and water conditions by making large-scale movements and increasing their 

home range size (Ferguson et al. 1999). Are changes in ice condition or food availability 

contributing to the increased use of coastal habitat in the Beaufort Sea? Is the presence of large 

males at the carcass sites an indicator of food stress in the marine environment? What is the 

overall contribution of whale remains to the energetic needs of polar bears? Future studies are 

needed to examine space-use patterns of individual polar bears to determine to what extent 

coastal use by polar bears is increasing, and to what extent the presence of bowhead whale 

carcasses are affecting that trend. 

The study has also increased awareness to a growing concern over large numbers of bears 

concentrating near human developments, and the subsequent potential for increased bear-human 

conflicts. The Fish and Wildlife Service’s goal is to minimize polar bear-human conflicts by 

minimizing polar bear-human interactions and decreasing bear densities in proximity to human 

settlements. Information obtained from this study will be used to guide management activities 

such as: 1) cooperative development of bear-human interaction plans with affected villages; 2) 

identifying options for minimizing attractants within and around human settlements; 3) 

increasing information and education on polar bear life history and the risks associated with 

increased bear use of coastal areas; and 4) structuring village-based polar bear patrols. 

One of the primary concerns related to polar bear use of whale carcasses deposited near human 

settlements is to what extent polar bears are becoming food-conditioned to bowhead whale 

remains, namely, associating humans with a source of food. Past studies indicate that foodconditioned bears are most likely to pose a risk to humans (Herrero and Herrero 1997). A study 

is needed at Barter Island to follow specific polar bears and monitor their movements and 

behavior within and between years in relation to human settlements. Currently, scientists in 
25

Alaska are investigating the use of Radio Frequency Identification (RFID) tags on polar and 

brown bears to track individual bears. If this technology proves successful, it could be used on 

Barter Island to: 1) identify and manage “problem” bears; 2) determine whether individual bears 

and their offspring return to Barter Island to feed on whale remains in subsequent years; and 3) 

more clearly evaluate the factors affecting the duration of residency of individual bears at Barter 

Island. 

Finally, use of carcass remains along the coast of Alaska has also drawn attention to the potential 

for increased risk of disease transmission among both marine (polar bear) and terrestrial (grizzly 

bears, foxes, gulls) species when using the same food resources. Future studies are needed to 

address whether pathogens (viruses and protozoa) are present and being transmitted among polar 

bears and other species. 

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28

Appendix 1. Field Data Collection Definitions 

Age/Sex Classification 

Age Sex Dependents 

Adult (A) = > 5 years old Male (M) Cub of the year (COY) = <1 year old 

Sub-adult (S) = 2.5-5 years old Female (F) Yearling (Y) = 1-2.5 year-old 

Unknown (U) = unknown age Unknown (U) = unknown sex N/A = no dependent animals 

Behavior/Activities 

Sitting (si)

resting (r)

attentive (a)

comfort (c)

grooming (g)

Laying (la)

resting (r) 

sleeping (s) 

comfort (c) 

grooming (g) 

Standing (st)

attentive (a) 

comfort (c) 

grooming (g) 

Walking (wk) Running (ru)

Feeding (fe)

whale (w) 

kill (k) 

snow/ice (s) 

herbaceous (h) 

urine (u) 

other (o) 

Interacting (in)

play (p) 

aggressive (ag) 

fight (f) 

neutral (n) 

submissive (s) 

other (o) 

Interacting 

Family (if)

Playing (pl) Swimming (sw)

Rolling (ro) Urination (ur) Defecation (df) Unobservable (uo) Other (ot)

Definitions

Sitting: body positioned on haunches 

resting - eyes open but not focused on stimuli 

attentive - alert; focused on a perceived stimulus 

comfort - scratching, rubbing, or stretching body 

grooming - using tongue, snow, water, or ice to lick body 

Laying: body positioned prone on ground on either belly, back or side 

resting - same as above 

sleeping - eyes closed and not reacting to stimuli 

comfort - same as above 

grooming - same as above 

Standing: body positioned on either hind or all four legs 

attentive - same as above 

comfort - same as above 

grooming - same as above

Walking: moving on all four legs at a slow pace 

Running: moving at a trot or lope on all four legs 

Feeding: ingesting food, including biting, chewing, swallowing, and/or looking for food ( short bouts of < 1minute 

of moving and/or sniffing with head lowered to the ground while in close proximity (10 m) of food source; includes 

carrying food in mouth 
29

whale - whale carcass 

kill - fresh kill (note species) 

herbaceous - plant material 

snow/ice - snow or ice 

urine - animal urine 

other - anything not listed above 

Interacting: subject interacting with another bear(s) outside its family group 

play - non-aggressive social interaction; play fighting 

Aggressive - dominant social display such as huffing or charging without contact with other bear(s) 

Fight - aggressive social interaction involving contact with another bear(s) 

Neutral - social interaction that involves posturing or other non-aggressive or submissive displays 

Submissive - social interaction that results in subject retreating away from other bear(s) 

Interacting family: adult female polar bear interacting with her dependent cubs; includes nursing 

Playing: handling an object 

Swimming: moving through water with feet not touching the bottom surface; if wading, classify as walking but 

change habitat code to Aopen water@ (see below) 

Rolling: moving from side to side with body in contact with the ground 

Urination: releasing a liquid bowel movement 

Defecation: releasing a solid bowel movement 

Unobservable: out of view of the observer(s) 

Other: anything not included above (describe in notes)

Habitat Types

Open water (OW) = marine environment 

Shorefast ice (SH) = shore-fast ice attached to the mainland or barrier islands 

Pack ice (PI)= unconsolidated active pack ice such as ice pans or bergs 

Barrier Island (BI) = land surrounded on all sides by water; includes all of Cross Island and Bernard Spit 

Mainland (MA) = land attached to the Coastal Plain; includes Barter Island 

Unknown (UH) = unknown habitat type 

Habitat types within the study area were defined as: mainland (Barter Island feeding site and all visible areas except 

Bernard Spit and open water), barrier island (Cross Island, Bernard Spit), or open water (non-terrestrial marine 

areas).