Summary of 2007 Biological Survey Activities


A. Porcupine Caribou Herd

During the winter of 2006-2007, most of the Porcupine Caribou Herd (Porcupine Herd) wintered in or near the Richardson Mountains, west of Aklavik, Northwest Territories. Smaller numbers of caribou wintered in the Ogilvie Basin in the central Yukon and along the Sheenjek River in Alaska. Caribou began moving north by mid April and most of the herd was between the Blow and Firth Rivers by late April 2007.

From mid April through early June, the weather was cool and foggy on the northeastern coastal plain of Alaska and snow melt was delayed. Much of the traditional calving area in the Arctic Refuge was covered with snow in early June, while the snow had melted east of the USA-Canada border. As a result, most of the Porcupine Herd calved in the northern Yukon Territory. The peak of calving occurred around 30 May.

Arctic Refuge staff flew tracking flights to locate caribou on 23-25 May 2007. The annual calving survey of the Porcupine herd was conducted by the Alaska Department of Fish and Game (ADF&G) on 2-4 June 2007. Of 79 cows observed, 50 had calves, 13 were still pregnant or had given birth and lost a calf, and 8 (all 2 year olds) were likely not pregnant.

caribou aggregationBy mid-June, most of the Porcupine Herd had moved onto the refuge to feed and escape harassment by insects and predators. Biologists from Arctic Refuge and ADF&G conducted surveys in late June to determine which calves survived and to estimate the proportion of cows accompanied by calves. Most of the Porcupine Herd was in the northern foothills of the Brooks Range in the Arctic Refuge at this time. Thirty seven of 42 caribou observed with calves in early June still had their calves in late June (88%). Twelve of 15 female caribou with satellite collars gave birth in 2007, and all that were seen in late June (10) still had their calves.

Cool cloudy weather in late June apparently caused the caribou to move south into the Brooks Range. A week later, when warm and sunny weather returned, caribou aggregated into groups scattered from the northern foothills near the Jago River, south and east to the headwaters of the Coleen River. A photo-census to estimate population numbers was attempted on 1 July, but was ultimately unsuccessful because caribou groups were too scattered throughout the mountains. The census will be attempted again in 2008.

Estimated calf production and survival were very high in June 2007. The herd wintered farther north than in recent years and range conditions may have been better. Spring migration was shorter and caribou arrived on the calving area and gave birth earlier. Mild weather and favorable snow conditions in the calving area probably contributed to higher calf survival.

As of February 2008, most of the herd is wintering near Arctic Village. The remainder is in the Yukon Territory between the Fishing Branch Management Area and the Upper Ogilvie River basin.

B. Central Arctic Caribou Herd

Research and monitoring of the Central Arctic Herd is being conducted primarily by biologists from ADF&G. This herd uses calving grounds east and west of the Sagavanirktok River, between the coast and the northern foothills of the Brooks Range. The most recent census of the herd in 2002 yielded a population estimate of 32,000. During summer, residents of Kaktovik generally harvest animals from the Central Arctic Herd on the Arctic Refuge's coastal plain west of Kaktovik. In winter and spring, Central Arctic Herd animals are found in the northern foothills and river valleys of the Brooks Range.

In 2006-2007, the majority of the Central Arctic Herd wintered in Gates of the Arctic National Park south of the crest of the Brooks Range mountains or along the northwestern boundary of the Arctic Refuge in the northern foothills of the Brooks Range. Some additional caribou wintered in the Middle Fork of the Chandalar River and the Wind River.

In early June 2007, ADF&G located 59 radio-collared caribou cows from the Central Arctic Herd. Thirty nine were pregnant and 16 were accompanied by calves. In late June, 46 of 57 caribou had calves. Thirty two calves radio-collared in June 2006 and still alive in July 2006 were followed until early June 2007. Annual survival rates were 70% for calves living in the west and 43% for calves living in the east, in and near the Arctic Refuge.

The Central Arctic Herd has used western areas of the Arctic Refuge more frequently and in larger numbers over the past few years. The greatest increase in use of the Refuge has occurred during July, when caribou aggregate near the coast to forage in habitats that provide relief from biting insects. In 2007 a large portion of the herd was found near Camden Bay.

Dall Sheep

A. Hulahula River

Biologists from the Arctic Refuge conducted a sex and age composition survey for Dall sheep along the Hulahula River in June 2007. Biologists traveled the survey route by foot. Sheep were observed with a high-power telescope and classified by sex and age, (i.e., lamb, yearling, 2-year old ram or ewe, adult ewe, and adult ram). Adult rams were further classified according to the degree of horn curl. Similar surveys were conducted in this area between 2003 and 2006.

dall ewesIn 2007, 24 groups of sheep totaling 470 individuals were observed. The lamb-ewe ratio was 24.8 lambs per 100 ewes. This rather low lamb production was expected because ewes do not produce a lamb every year in the Hulahula drainage, and lamb production has been high for the past three years. The observed ratio of 34 yearlings per 100 ewes in 2007 was about average. Few adult rams were seen, probably because spring came early this year and sheep were at higher elevations and more scattered through the mountains.

B. Atigun Pass

Arctic Refuge biologists conducted a survey of Dall sheep along the Atigun River north of Atigun Pass on 11-12 June 2007. The objectives of the survey were: (1) estimate age and sex composition for this sheep population; and (2) document distribution of sheep within the survey area. The survey route followed the Dalton Highway from Atigun Pass to Galbraith Lake, then continued along the Atigun River into the Refuge through Atigun Gorge. Biologists traveled by vehicle along the road portion of the route, then on foot through the gorge. This survey has been conducted annually since 1986.

Biologists observed 120 Dall sheep in 18 groups, including 22 rams and 44 adult ewes. Group size averaged 6.7 sheep, and ranged from 1 to 26. There were 43.2 lambs per 100 ewes in our count, which is similar to the 20-year average for this area (44.1 lambs per 100 ewes) and to the number observed in 2006 (44.7 lambs per 100 ewes). We estimated 27.3 yearlings per 100 ewes, suggesting that approximately 44% of the lambs seen in June 2006 survived to June 2007.

C. Arctic Village Sheep Management Area (AVSMA)

The AVSMA was established in 1991 to cover the area west of the East Fork Chandalar River between Crow Nest and Cane Creeks, north and west of Arctic Village. The area was expanded in 1995 to include the entire drainages of Red Sheep and Cane Creeks. Within this area, sheep hunting by non-Federally qualified hunters was prohibited.

Studies of Dall Sheep abundance, distribution, and movements in the AVSMA and vicinity were conducted during 1990-1995. In response to a proposal before the Federal Subsistence Board to open the Management Area to sport hunting, Arctic Refuge staff conducted an aerial survey of the northern portion of the AVSMA in June 2006, including the Red Sheep Creek and Cane Creek drainages. Biologists estimated that the density of Dall sheep was 1.7 per square mile in this area, slightly less than the 1990-1991 estimates of 1.9 to 2.2 sheep per square mile. The aerial survey was repeated in June 2007 in the Red Sheep Creek and Cane Creek drainages only. Results of this survey suggested a density of 0.81 Dall sheep per square mile, which is less than half the density estimated for this area in 2006. This change may reflect a declining sheep population and/or a redistribution of sheep.

The Federal Subsistence Board approved a temporary Special Action to open hunting for full-curl rams to non-Federally qualified hunters in the Red Sheep Creek and Cane Creek drainages in 2006, and made this change permanent in 2007. Non-Federally qualified hunters may hunt sheep here between August 10 and September 20, 2007.

Refuge staff monitored public use at the Red Sheep Creek Airstrip from August 7 to 25, 2006 and August 8 to 27, 2007. This airstrip was often used by hunters before the AVSMA was established. In 2006, a total of 10 groups were observed using the airstrip and four groups were observed hunting in the AVSMA. In 2007, only one group was observed using the airstrip and no groups were observed hunting. Observers recorded 25 and 22 overhead flights in 2006 and 2007, respectively. These monitoring efforts provided minimum estimates of public use for the immediate vicinity of the Red Sheep Creek airstrip only. A final report will be available after an aerial survey of snow machine use is conducted during spring 2008.


The abundance of moose in northeast Alaska declined precipitously in the early to mid 1990s and remains low within Game Management Unit 26(C), the coastal plain and North Slope of the Brooks Range within the Arctic Refuge. In response to the decline, subsistence and sport hunting of moose in this unit was closed in 1996.

Sport hunting remains closed for moose in Unit 26(C), while the subsistence harvest was reopened beginning with the 2004-2005 season. During the 2007-2008 season, residents of Kaktovik will be allowed to take up to 3 moose from Units 26(B) and 26(C), but no more than 2 bulls in Unit 26(C), and no cows may be taken in Unit 26(C).

In April 2007, Arctic Refuge staff conducted an aerial moose survey of the entire Refuge coastal plain and all major river drainages from the Canadian border up to, but not including, the Canning River. We observed 59 moose. Forty-nine (83%) of these were in the Aichilik, Egaksrak and Kongakut River drainages. During similar surveys in 2003 and 2005 we recorded 52 and 47 moose, respectively. These data suggest that the population of moose on the North Slope of the Refuge remains low, and has not recovered enough to allow increased harvest.


A population of muskoxen restored to the Arctic Refuge coastal plain grew rapidly from 1974 to 1986, expanded its range east and west, and was relatively stable until 1998. In recent years, however, numbers of muskoxen in the Arctic Refuge declined. Biologists counted 5 muskoxen in the northern portion of the Refuge during a pre-calving census in April 2007, and only 1 muskox was seen in this same area in 2006.

muskoxenThe decline in numbers of muskoxen was likely caused by low calf survival in some years, increased adult mortality, and changes in distribution of the population. Several interacting factors likely affect population size and distribution of muskoxen in northeastern Alaska. These include severe weather conditions such as icing events and deep snow that reduce access to winter forage and increase energetic costs, diseases and parasites that affect body condition, and predation, primarily by grizzly bears. The Alaska Department of Fish and Game has begun a study to determine muskox calf production and sources of calf mortality. Blood samples collected from muskoxen captured as part of this study are checked for disease and other conditions such as copper deficiency that may be affecting survival rates of calves and adults. Carcasses of calves and adults are also examined to determine cause of death. Subsistence harvest regulations state that the number of permits issued to hunt muskoxen in Unit 26(C) should not exceed 3% of the number seen during the pre-calving census. Because fewer than 34 animals were observed this year in Unit 26(C), no permits to hunt muskoxen were issued for the 2007-2008 season.

Grizzly Bears

Estimated density of grizzly bears in north-central Alaska north of the Brooks Range and in the Canning River drainage is 18.3 bears per 1000 square kilometers. This estimate was based on surveys conducted in 2001-2003. In 2006-2007, Arctic Refuge biologists, in cooperation with the Alaska Department of Fish and Game and others, monitored grizzly bears on the coastal plain and in the northern foothills of the Arctic Refuge. Four male grizzly bears were followed using satellite telemetry to determine high-use areas, important habitats, possible predation events, and denning sites. The bears were remotely located up to ten times a day and were visually observed 13 times between May 2006 and July 2007. Ground visits to 38 high-use sites showed that these bears fed on carcasses (primarily caribou) and dug up roots in Arpil and May when the ground was still snow-covered. Bears ate sedges, grasses and other non-woody plants during the growing season, and berries and roots in late summer and fall. Lemming numbers were very high in 2006, and were an important food source for bears that year. In a related study, blood and hair samples from bears were analyzed to determine diets of grizzly bears living in and near the Refuge. This information will help managers understand the relationship between grizzly bears and their prey. Preliminary results suggest that the diet of these bears consists of 55% plants and 45% meat. The amount of vegetation versus meat in bear diets has not changed significantly over the last 35 years.



The Arctic Coastal Plain within the Arctic Refuge is an important breeding and post-breeding area for several species of birds, especially shorebirds and waterfowl. Many of these species are declining in abundance, particularly due to loss of overwintering and migratory habitats south of Alaska. In 2007, Refuge biologists conducted studies of shorebird populations on the Arctic Refuge, and assisted in the statewide avian influenza (H5N1) surveillance effort.

The Arctic Coastal Plain provides important habitat for shorebirds after breeding as they prepare for long-distance southward migrations to wintering grounds. From July to September, shorebirds aggregate in large groups near the coast to feed, thereby acquiring fat necessary for successful migration. Starting in 2005, Refuge biologists joined with other researchers to study the abundance, distribution, movement patterns, feeding habits, and physiology of these birds during the critical post-breeding period. Previous years' study sites on the Arctic Refuge include sites on the Canning, Hulahula, and Okpilak River Deltas. Biologists used boats to also survey staging birds at all other deltas in 2006. Results from 2006 identified several important staging areas and indicated that the Canning River Delta is a high-use area for post-breeding shorebirds.

Refuge biologists continued investigations in 2007 at a site on the main branch of the Canning River and repeated the survey for staging birds at other major deltas along the Refuge's coast. Results improved understanding of the importance of the Canning River region and other key areas on the Refuge for post-breeding shorebirds.

juvenile long-billed dowitchersDuring the 2005-07 studies, Refuge biologists identified several important areas for post-breeding shorebirds on the Arctic Refuge coast, but other aspects of shorebird ecology during this period remain unknown. There was considerable variability in use of coastal habitats between years and sites. Causes for this variability are unknown, but may include weather, wind, and water conditions, all of which likely affect food availability for shorebirds. In 2008, Refuge biologists will further investigate how these factors affect the distribution and abundance of shorebirds. They also plan to work with researchers from the University of Texas to investigate distribution of food sources (invertebrates) in shorebird habitats. Researchers' overall objectives are to identify important areas for these birds and to understand what factors might be affecting their ability to successfully reproduce and migrate.

In 2007, Refuge staff continued to collect samples from high-priority shorebird species to test for exposure to highly pathogenic avian influenza (H5N1). Similar efforts in 2006 did not detect the presence of this virus in any of the samples collected on the Refuge. At the Canning River Delta breeding site biologists were unable to meet their goal of 85 samples because of poor nest success. However, a total of 36 samples were collected from Dunlin (n=12), Ruddy Turnstone (n=4), Pectoral Sandpiper (n=18), and Buff-breasted Sandpiper (n=2). During the post-breeding project on the main branch of the Canning River, biologists collected 90 samples from Dunlin (n=22), Ruddy Turnstone (n=1), Pectoral Sandpiper (n=30), Long-billed Dowitcher (n=1), Buff-breasted Sandpiper(n=3), Semipalmated Sandpiper (n=15), Stilt Sandpiper (n=6), Western Sandpiper (n=2), Red-necked Phalarope (n=9), and Long-tailed Duck (n=1). None of these samples were positive for exposure to the H5N1 virus. In 2008, Refuge biologists plan to continue their avian influenza surveillance efforts.


smith's longspur maleSmith's Longspurs are a small, rare landbird that breeds in arctic Alaska and Canada, and overwinters in the southern United States. The Arctic Refuge is likely the only National Wildlife Refuge in the U.S. with breeding populations of this species. The area in the south-central United States used by the species for overwintering is relatively small and extensively altered by human development. For this reason, Smith's Longspurs have been recognized as a species of concern by the U.S. Fish and Wildlife Service, Boreal Partners in Flight, and the Alaska Bird Observatory. In 2006, Refuge biologists initiated studies on Smith's Longspurs at Sunset Pass in the Sadlerochit Mountains. In 2007, they continued their studies in Atigun Gorge. In partnership with the University of Alaska and others, they will study the breeding ecology, abundance, distribution, and habitat associations of Smith's Longspurs on the Arctic Refuge and other regions in northern Alaska.

Fish and Other Aquatic Organisms

A. Dolly Varden on the Hulahula River

Dolly Varden in the Hulahula River were counted during 2007 using fixed-location, Dual Frequency Identification Sonar (DIDSON) to assess their population status. Sonar operations began in July and continued to mid-September. DIDSON is a multi-beam sonar with a unique acoustic lens system designed to focus the beam to create high-resolution images. The high-resolution image provides a clear and distinct fish image and a wider viewing angle in the horizontal and vertical plane.

dolly varden small

didson animation

B. Coastal Lagoons

The coastal lagoons of the Arctic Refuge support significant populations of fish and wildlife, including many species important for subsistence harvest. The biological communities that use these lagoons are also believed to be extremely vulnerable to effects of climate change and to human activities such as exploration and development within recently leased tracts in the eastern Beaufort Sea. Increased understanding of the ecology of the lagoons is essential for documenting future changes and for mitigating potential impacts.

The Arctic Refuge, in partnership with several other organizations, is actively involved in a number of studies directed at understanding and protecting these arctic coastal lagoons. For example, in 2007 researchers from the University of Texas and the University of Alaska conducted inventories of invertebrates, both on the bottom of the lagoons and in the water column. These invertebrates are an important food source for birds, many of which stop over in the lagoons before migrating south for the winter. Refuge staff, in cooperation with the University of Alaska and Manomet Center for Conservation Science, in Massachusetts, documented the distribution of shorebirds during this post-breeding period to identify important areas. Much of the shorebird use is concentrated at river deltas, and samples were collected to determine what organisms may be particularly important food sources for these birds. Future reports will include the results of these studies.

Arctic Refuge staff also worked with biologists and consultants for Shell Oil Company in 2007 to identify vulnerable areas along the coast and strategies for protection in the event of an oil spill associated with Shell's offshore exploration program.

Scientists from the Refuge, the University of Alaska, and the University of Texas Marine Science Institute would like to thank the people of Kaktovik for their help in 2007, particularly the children who assisted with measuring and identifying samples taken from the sea for study.