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USGS1995

Wolves and caribou in Denali National Park, Alaska

Management of gray wolves ( Canis lupus ) and their prey in interior Alaska has been controversial for three decades (Harbo and Dean 1983). Recently, debate was rekindled with renewed interest in wolf control to bolster two populations of caribou ( Rangifer tarandus ). Our research in Denali National Park provides insights into the declines in caribou numbers over the last few years that are the basis of recent wolf control proposals. Our observations of fluctuating populations also illustrate the complexity of managing these predator-prey systems to meet a diverse array of public interests. Wolves and caribou are two components of the large mammal community of Denali National Park that also includes grizzly bears ( Ursus arctos ), moose ( Alces alces ), and Dall sheep ( Ovis dalli ). With the 1980 park expansion to more than 18,800 km2 (7,300 mi2) of central Alaska, this large mammal system became the only one of its kind that is virtually unaffected by human harvest. Therefore, Denali provides a unique opportunity to understand the natural interactions of these species and serves as a baseline for comparison with areas where hunting or other active wildlife management occurs. We have studied Denali's wolves and caribou since 1986 to determine their numbers and status and understand their natural interactions in this protected subarctic ecosystem. Our studies began near the end of more than a decade of mostly light winter snowfalls of around 100 cm (39 in)/yr. Since winter 1988-89, we have experienced five consecutive winters with above-average snowfalls, including two record-setting years. During winters 1990-91 and 1992-93, more than 390 cm (154 in) of snow fell, four times as much as in the early years of our study. This change in snowfall had profound effects on the wildlife in central Alaska. The population trends of Denali's caribou and wolves are strong evidence of the natural fluctuations to be expected in species inhabiting such dynamic and variable environments.

Alaska↗

USGS1995

Patterns of prey selection by wolves in Denali National Park, Alaska

The patterns of selection by wolves ( Canis lupu s) preying on moose ( Alces alces ), caribou ( Rangifer tarandus ), and Dall sheep ( Ovis dalli) in Denali National Park and Preserve, Alaska were studied from 1986 through early 1992. Wolves and their prey are legally protected or relatively unharvested in most of the area, and wolf numbers doubled during the study. Based on remains of 294 moose, 225 caribou, and 63 sheep, wolves killed calves and old adults disproportionately, and individuals with low marrow fat, jaw necrosis, or arthritis. Seasonal trends in proportions of various species, ages, and sex of kills were found. During the winters following winters of deep snowfalls, wolves greatly increased the proportion of caribou cows and calves taken. We conclude that in a natural system, wolves can survive on vulnerable prey even during moderate weather, and when snowfall exceeds average, they can respond by switching to newly vulnerable prey and greatly increasing their numbers.

Occasional Publication of the Canadian Circumpolar↗

USGS2003

The Chernobyl Nuclear Power Plant accident: ecotoxicological update

The accident at the Chernobyl, Ukraine, nuclear reactor on 26 April 1986 released large amounts of radiocesium and other radionuclides into the environment, contaminating much of the northern hemisphere, especially Europe. In the vicinity of Chernobyl, at least 30 people died, more than 115,000 others were evacuated, and consumption of milk and other foods was banned because of radiocontamination. At least 14,000 human cancer deaths are expected in Russia, Belarus, and the Ukraine as a direct result of Chernobyl. The most sensitive local ecosystems, as judged by survival, were the soil fauna, pine forest communities, and certain populations of rodents. Elsewhere, fallout from Chernobyl significantly contaminated freshwater and terrestrial ecosystems and flesh and milk of domestic livestock; in many cases, radionuclide concentrations in biological samples exceeded current radiation protection guidelines. Reindeer (Rangifer tarandus) in Scandinavia were among the most seriously afflicted by Chernobyl fallout, probably because their main food during winter (lichens) is an efficient absorber of airborne particles containing radiocesium. Some reindeer calves contaminated with 137Cs from Chernobyl showed 137Cs-dependent decreases in survival and increases in frequency of chromosomal aberrations. Although radiation levels in the biosphere are declining with time, latent effects of initial exposure--including an increased frequency of thyroid and other cancers--are now measurable. The full effect of the Chernobyl nuclear reactor accident on natural resources will probably not be known for at least several decades because of gaps in data on long-term genetic and reproductive effects and on radiocesium cycling and toxicokinetics.

Book chapter↗

USGS1998

Caribou antlers as nest materials for golden eagles in northwestern Alaska

There are few published records of antlers in golden eagle (Aquila chrysaetos) nests. This note reports extensive use of caribou (Rangifer tarandus) antlers in three golden eagle nests in the Cape Kruzenstern region of northwestern Alaska. The importance of antlers to this population of eagles can be explained at least in part by (1) the lack of suitable woody vegetation on the open tundra, (2) the similarity of antlers to sticks, and (3) the abundance of antlers, especially cow caribou antlers, in the region.

Journal of Raptor Research↗

USGS2003

Evaluation of an expandable, breakaway radiocollar for white-tailed deer fawns

We evaluated an expandable, breakaway VHF radiocollar design for use on white-tailed deer (Odocoileus virginianus) from birth to about 1 year of age. A similar collar design has been used on caribou (Rangifer tarandus), but we found that the collar did not expand quickly enough to accommodate increase in neck circumference of fawns during the first 2 months of life. Consequently, we modified the stitching pattern so that the first expansion fold opened faster. We monitored performance of this modification on free-ranging and captive fawns. Also, we collected data on neck growth in fawns to document design requirements of expandable collars for white-tailed deer. Mean neck circumference at ???14 days of age of free-ranging fawns in Pennsylvania was 17.8 cm (SD=1.67, n=62) for males and 17.3 cm (SD=1.50, n=52) for females. Based on measurements of captive fawns, neck circumference increased 8.8 cm from birth to August, 2.5 cm from August to October, and 2.6 cm from October to March. Observations of captive fawns fitted with dummy radiocollars indicated that collars expanded when needed and caused no apparent discomfort to fawns. We detected no problems with use of 86 collars on 113 free-ranging fawns for >270 days and recovered radiocollars expanded as designed. The elastic collar material failed on 3 collars (3%) after 142, 207, and 226 days on fawns, and 1-5 radiocollars (???4%) were cast by fawns. Our modification to this radiocollar design reduced fawn discomfort or suffering, allowing researchers to better comply with principles of the Animal Welfare Act.

Wildlife Society Bulletin↗

USGS1998

Satellite telemetry: A new tool for wildlife research and management

The U.S. Fish and Wildlife Service and the Alaska Department of Fish and Game have cooperated since 1984 to develop and evaluate satellite telemetry as a means of overcoming the high costs and logistical problems of conventional VHF (very high frequency) radiotelemetry systems. Detailed locational and behavioral data on caribou ( Rangifer tarandus ), polar bears ( Ursus maritimus ), and other large mammals in Alaska have been obtained using the Argos Data Collection and Location System (DCLS). The Argos system, a cooperative project of the Centre National d'Études Spatiales of France, the National Oceanic and Atmospheric Administration, and the National Aeronautics and Space Administration, is designed to acquire environmental data on a routine basis from anywhere on earth. Transmitters weighing 1.6-2.0 kg and functioning approximately 12-18 months operated on a frequency of 401.650 MHz. Signals from the transmitters were received by Argos DCLS instruments aboard two Tiros-N weather satellites in sun-synchronous, nearpolar orbits. Data from the satellites were received at tracking stations, transferred to processing centers in Maryland and France, and made available to users via computer tape, printouts, or telephone links. During 1985 and 1986, more than 25,000 locations and an additional 28,000 sets of sensor data (transmitter temperature and short-term and long-term indices of animal activity) were acquired for caribou and polar bears. Locations were calculated from the Doppler shift in the transmitted signal as the satellite approached and then moved away from the transmitter. The mean locational error for transmitters at known locations (n - 1,265) was 829 m; 90% of the calculated locations were within 1,700 m of the true location. Caribou transmitters provided a mean of 3.1 (+5.0. SD) locations per day during 6h of daily operation, and polar bear transmitters provided 1.7 (+6.9SD) locations during 12h of operation every third day. During the first 6 months of operation, the UHF (ultra-high frequency) signal failed on three of 32 caribou transmitters and 10 of 36 polar bear transmitters. A geographic information system (GIS) incorporating other databases (e.g., land cover, elevation, slope, aspect, hydrology, ice distribution) was used to analyze and display detailed locational and behavioral data collected via satellite. Examples of GIS applications to research projects using satellite telemetry and examples of detailed movement patterns of caribou and polar bears are presented. This report includes documentation for computer software packages for processing Argos data and presents developments, as of March 1987, in transmitter design, data retrieval using a local user terminal, computer software, and sensor development and calibration.

Resource Publication↗

USGS2001

Effects of recent climate warming on caribou habitat and calf survival

Migratory Barren-Ground Caribou Rangifer tarandus granti are the most important subsistence resource for northern indigenous peoples. They are likely to respond to global climatic changes that affect the distribution of their forage resources and the availability of forage through the year. The Porcupine Caribou herd is a large, internationally migratory herd of about 128,000 individuals that occupies the Alaska-Canada borderlands and uses a 300,000 km 2 annual range. The calving ground is a traditionally-used portion of the annual range that comprises 23,000 km 2 at approximately 70° north. Caribou migrate several hundred kilometres from winter ranges to the calving ground, arriving in mid- to late-May each year. Calves are born during the first week of June, and cows and calves remain on the calving ground for 4-6 weeks before dispersing to late-summer, fall, and winter ranges. We measured the relative amount of green vegetation using data from polar orbiting satellites (Figure 1) to assess decade-long temporal trends in large scale habitat conditions on the calving ground and to investigate Caribou response to this habitat change. The vegetation index has shown a tendency toward earlier greening in spring and later plant senescence (dying off) in much of the northern hemisphere the 1980s, concurrent with independent estimates of climate change. High density calving was consistently located where the daily rate of increase in the amount of green plant biomass during lactation was greatest, in the period 1985-1996. This was probably because of the lactating cows' need for highly digestible new plant growth. Nutritional requirements of lactating cows are about double those during the remainder of the year.

Alaska, Yukon Territory↗

USGS2002

Predators

Calving caribou ( Rangifer tarandus ) of the Central Arctic herd, Alaska, have avoided the infrastructure associated with the complex of petroleum development areas from Prudhoe Bay to Kuparuk (Cameron et al. 1992, Nellemann and Cameron 1998, and Section 4 of this document). Calving females of the Porcupine caribou herd may similarly avoid any oil field roads and pipelines developed in areas traditionally used during the calving and post-calving periods. This may displace the caribou females and calves to areas east and south of the 1002 Area of the Arctic National Wildlife Refuge. Increased calf mortality could occur if calving caribou are displaced into areas that have a higher density of predators, higher rates of predation, or where a higher proportion of the predators regularly use caribou as a food source (Whitten et al. 1992). Our study assessed predation risks to caribou calving in the 1002 Area versus calving in potential displacement areas. Due to funding constraints, our research focused on grizzly bears ( Ursus arctos ), with wolves (Camus lupus) and golden eagles ( Aquila chrysaetos ) receiving only cursory attention. Our research objectives were 1) to compare relative abundance of predators within the 1002 Area with that in adjacent peripheral areas, 2) to determine factors affecting predator abundance on the calving grounds, and 3) to quantify the use of caribou as a food source for predators and the importance of caribou to the productivity of predator populations using the coastal plain of the Arctic National Wildlife Refuge.

Alaska, Northwest Territories, Yukon Territory↗

USGS2006

Interrelationships of Denali's large mammal community

Along with its sweeping mountain landscapes, Denali National Park and Preserve (Denali) is probably best known for opportunities to observe the large mammals common to Interior Alaska. Locally known as the “Big Five,” gray wolves ( Canis lupus ), grizzly bears ( Ursus arctos ),moose ( Alces alces ), caribou ( Rangifer tarandus ) and Dall sheep ( Ovis dalli ) have coexisted in the region for millennia. While many other animals occur in Denali, none are as readily associated with the park environment as these species. In addition to the opportunities for viewing or photographing Interior Alaska’s large mammals, Denali is a great natural laboratory to study the species and their interrelationships. Unlike the rest of Interior Alaska, the Denali carnivore/ungulate community has been little affected by human harvests for several decades, and interactions of these species are driven largely by natural phenomena. It is a common perception that large mammals are “abundant” within the protected confines of the park boundaries, but that is not the case. Throughout much of Interior Alaska, large mammals occur at low densities naturally, and Denali is no exception. Although Denali encompasses over 6,600 square miles (17,100 km2 ) of suitable habitat, currently about 100 wolves, 350 grizzly bears, 2,000 caribou, 1,900 moose, and 1,800 Dall sheep occur there. In comparison, areas of the Tanana Flats and northern Alaska Range adjacent to Denali on the east have long been managed for human harvests, and moose occur there at about six times the density of Denali.

Alaska↗

USGS2002

The porcupine caribou herd

Documentation of the natural range of variation in ecological, life history, and physiological characteristics of caribou ( Rangifer tarandus ) of the Porcupine caribou herd is a necessary base for detecting or predicting any potential effects of industrial development on the performance (e.g., distribution, demography, weight-gain of individuals) of the herd. To demonstrate an effect of development, post-development performance must differ from pre-development performance while accounting for any natural environmental trends. We had 2 working hypotheses for our investigations: 1) performance of the Porcupine caribou herd was associated with environmental patterns and habitat quality, and 2) access to important habitats was a key influence on demography. We sought to document the range of natural variation in habitat conditions, herd size, demography (defined here as survival and reproduction), sources and magnitude of mortality, distribution, habitat use, and weight gain and loss, and to develop an understanding of the interactions among these characteristics of the herd. In addition, we investigated ways that we could use this background information, combined with auxiliary information from the adjacent Central Arctic caribou herd, to predict the direction and magnitude of any potential effects of industrial oil development in the 1002 Area of the Arctic National Wildlife Refuge on Porcupine caribou herd calf survival on the herd's calving grounds during June.

Alaska, Northwest Territories, Yukon Territory↗

USGS1989

Twenty-four hour behavior patterns and budgets of free-ranging reindeer in winter

To obtain movement data on wild fulvous tree ducks (Dendrocygna bicolor) 165 immature pen-reared fulvous tree ducks were color-marked and released in three southeast Texas counties in July October 1969/70. Nine (5 percent) of the marked birds were recovered from 3 days to 9 months after release, and an additional 15 birds provided sight records. Many released birds apparently became integrated into the wild population; all of those observed were with wild flocks. Six birds were recovered over 50 miles from the release sites. Four released in late July to mid-September had moved eastward and two went southward in September or later. Five were still in the Texas-Louisiana rice belt (three in late November). The sixth bird was recovered in October in Veracruz, which supports the assumption that U.S. Gulf Coast nesting populations winter in southern Mexico.

Rangifer↗