Search

Many animals migrate to take advantage of temporal and spatial variability in resources. These benefits are offset with costs like increased energetic expenditure and travel through unfamiliar areas. Differences in the cost-benefit ratio for individuals may lead to partial migration with one portion of a population migrating while another does not. We investigated migration dynamics and winter site fidelity for a long-distance partial migrant, barren ground caribou (Rangifer tarandus granti) of the Teshekpuk Caribou Herd in northern Alaska. We used GPS telemetry for 76 female caribou over 164 annual movement trajectories to identify timing and location of migration and winter use, proportion of migrants, and fidelity to different herd wintering areas. We found within-individual variation in movement behavior and wintering area use by the Teshekpuk Caribou Herd, adding caribou to the growing list of ungulates that can exhibit migratory plasticity. Using a first passage time–net squared displacement approach, we classified 78.7% of annual movement paths as migration, 11.6% as residency, and 9.8% as another strategy. Timing and distance of migration varied by season and wintering area. Duration of migration was longer for fall migration than for spring, which may relate to the latter featuring more directed movement. Caribou utilized four wintering areas, with multiple areas used each year. This variation occurred not just among different individuals, but state sequence analyses indicated low fidelity of individuals to wintering areas among years. Variability in movement behavior can have fitness consequences. As caribou face the pressures of a rapidly warming Arctic and ongoing human development and activities, further research is needed to investigate what factors influence this diversity of behaviors in Alaska and across the circumpolar Arctic.

As evidenced by animal sign (scat, active nests, nesting materials, rodent runways) observed across five stabilized retrogressive thaw slumps and two areas of undisturbed upland tundra, Arctic birds and mammals on Herschel Island, Canada, use stabilized thaw slumps differently than undisturbed tundra. Rodent winter nests and scat were found exclusively in undisturbed tundra and at a 250-year-old stabilized thaw slump site, whereas rodent runways and Semipalmated Plover (Charadrius semipalmatus) nests were found exclusively at 10- and 20-year-old stabilized thaw slump sites. Bird scat was found in each tundra type, but was most common in the youngest sites, and the number of observations decreased with increasing site age. Caribou (Rangifer tarandus granti) scat was found at all sites, whereas Muskox (Ovibos moschatus) scat was not found at 20-year-old sites and was most common in undisturbed tundra. To our knowledge, these observations are the first examples of birds and mammals using stabilized thaw slump habitat of different ages, and they provide new avenues of research for Arctic wildlife biologists concerned with the adaptation of these animals to permafrost disturbance and the resulting changes in vegetation cover.

A distinguishing characteristic of many migratory animals is their annual return to distinct calving (birthing) areas in the spring, yet the navigational mechanisms employed during migration that result in this pattern are poorly understood. Effective conservation of these species requires reliable delineation of such areas, quantifying the factors that influence their selection, and understanding the underlying mechanisms resulting in use of calving areas. We used barren-ground caribou (Rangifer tarandus granti) as a study species and identified calving sites of the Western Arctic Herd in Alaska using GPS collar data from 2010–2017. We assessed variability in calving areas by comparing spatial delineations across all combinations of years. To understand calving area selection at a landscape scale, we performed a resource selection analysis comparing calving sites to available locations across the herd’s range and incorporated time-varying, remotely sensed metrics of vegetation quality and quantity. We found that whereas calving areas varied from year to year, this annual variation was centered on an area of recurring attraction consistent with previous studies covering the last six decades. Calving sites were characterized by high-quality forage at the average time of calving, but not peak calving that year, and by a narrow range of distinct physiographic factors. Each year, calving sites were located on areas of above-average conditions based on our predictive model. Our findings indicate that the pattern of spring migration for pregnant females was to migrate to areas that consistently provide high-quality forage when averaged across years, and then upon arriving at this calving ground, refine selection using their perception of annually varying conditions that are driven by environmental stochasticity. We suggest that the well-documented and widespread pattern of fidelity to calving grounds by caribou is supportive of a navigational mechanism based on spatial memory at a broad scale to optimize foraging and energy acquisition at a critical life-history stage. The extent to which migrants depend on memory to reach their spring destinations has implications for the adaptability of populations to changing climate and human impacts.

Migration is common worldwide as species access spatiotemporally varying resources and avoid predators and parasites. However, long‐distance migrations are increasingly imperiled due to development and habitat fragmentation. Improved understanding of migratory behavior has implications for conservation and management of migratory species, allowing identification and protection of seasonal ranges and migration corridors. We present a technique that applies circuit theory to predict future effects of development by analyzing season‐specific resistance to movement from anthropogenic and natural environmental features across an entire migratory path. We demonstrate the utility of our approach by examining potential effects of a proposed road system on barren ground caribou (Rangifer tarandus granti) and subsistence hunters in northern Alaska. Resource selection functions revealed migratory selection by caribou. We tested five scenarios relating habitat selection to landscape resistance using Circuitscape and GPS telemetry data. To examine the effect of potential roads on connectivity of migrating animals and human hunters, we compared current flow values near communities in the presence of proposed roads. Caribou avoided dense vegetation, rugged terrain, major rivers, and existing roads in both spring and fall. A negative linear relationship between resource selection and landscape resistance was strongly supported for fall migration while spring migration featured a negative logarithmic relationship. Overall patterns of caribou connectivity remained similar in the presence of proposed roads, though reduced current flow was predicted for communities near the center of current migration areas. Such data can inform decisions to allow or disallow projects or to select among alternative development proposals and mitigation measures, though consideration of cumulative effects of development is needed. Our approach is flexible and can easily be adapted to other species, locations and development scenarios to expand understanding of movement behavior and to evaluate proposed developments. Such information is vital to inform policy decisions that balance new development, resource user needs, and preservation of ecosystem function.

With industrial development expanding in the Arctic, there is increasing interest in quantifying the impacts of development projects on barren ground caribou (Rangifer tarandus granti). The primary data source to assess caribou distribution and predict impacts in remote areas of Alaska has shifted in recent decades from aerial survey data to telemetry data, but these techniques have different strengths and weaknesses. The ranges of two caribou herds, the Western Arctic Herd and the Teshekpuk Herd, overlap in northwest Alaska between Wainwright and Atqasuk, Alaska. Based on long-term telemetry data sets, this region was thought to be outside of the core calving ranges of both herds. Calving has long been reported to occur in this general area, but early reports assumed caribou were from the Western Arctic Herd and only one systematic aerial survey of caribou density and distribution during calving has been conducted in this area in recent decades. Following interest in industrial development in this area, we conducted aerial strip-transect surveys during early to mid-June 2013–2015 to directly assess the density and distribution of caribou in the area and we used existing telemetry data to compare our results to the seasonal distribution of both herds. Total caribou densities varied between 0.36 and 1.06 caribou/km² among years, and calf densities varied 0.04 and 0.25 calves/km² among years. Contrary to assumptions by early researchers in the area, telemetry data indicated that caribou in this area during early to mid-June were from the Teshekpuk Herd. The use of telemetry data alone underestimated the importance of this area for calving, but the combination of aerial surveys and telemetry data provided complementary information on caribou use of this area showing the importance of collecting the appropriate types of data for assessing potential impacts of development on caribou.

Mineral resource development in the Canadian north has tragic consequences for both caribou and Indigenous people., Sustaining arctic/subarctic ecosystems and the livelihoods of northern Indigenous peoples is an immense challenge amid increasing resource development. The paper describes a “tragedy of open access” occurring in Canada’s north as governments open up new areas of sensitive barren-ground caribou habitat to mineral resource development. Once numbering in the millions, barren-ground caribou populations (Rangifer tarandus groenlandicus/Rangifer tarandus granti) have declined over 70% in northern Canada over the last two decades in a cycle well understood by northern Indigenous peoples and scientists. However, as some herds reach critically low population levels, the impacts of human disturbance have become a major focus of debate in the north and elsewhere. A growing body of science and traditional knowledge research points to the adverse impacts of resource development; however, management efforts have been almost exclusively focused on controlling the subsistence harvest of northern Indigenous peoples. These efforts to control Indigenous harvesting parallel management practices during previous periods of caribou population decline (for example, 1950s) during which time governments also lacked evidence and appeared motivated by other values and interests in northern lands and resources. As mineral resource development advances in northern Canada and elsewhere, addressing this “science-policy gap” problem is critical to the sustainability of both caribou and people.

Wide-ranging mammals face significant conservation threats, and knowledge of the spatial scale of population structure and its drivers is needed to understand processes that maintain diversity in these species. We analysed DNA from 655 Alaskan caribou (Rangifer tarandus granti) from 20 herds that vary in population size, used 19 microsatellite loci to document genetic diversity and differentiation in Alaskan caribou, and examined the extent to which genetic differentiation was associated with hypothesized drivers of population subdivision including landscape features, population size and ecotype. We found that Alaskan caribou are subdivided into two hierarchically structured clusters: one group on the Alaska Peninsula containing discrete herds and one large group on the Mainland lacking differentiation between many herds. Population size, geographic distance, migratory ecotype and the Kvichak River at the nexus of the Alaska Peninsula were associated with genetic differentiation. Contrary to previous hypotheses, small Mainland herds were often differentiated genetically from large interconnected herds nearby, and genetic drift coupled with reduced gene flow may explain this pattern. Our results raise the possibility that behaviour helps to maintain genetic differentiation between some herds of different ecotypes. Alaskan caribou show remarkably high diversity and low differentiation over a broad geographic scale. These results increase information for the conservation of caribou and other migratory mammals threatened by population reductions and landscape barriers and may be broadly applicable to understanding the spatial scale and ecological drivers of population structure in widespread species.

Migration is an important component of the life history of many animals, but persistence of large-scale terrestrial migrations is being challenged by environmental changes that fragment habitats and create obstacles to animal movements. In northern Alaska, the Central Arctic herd (CAH) of barren-ground caribou (Rangifer tarandus granti) is known to migrate over large distances, but the herd's seasonal distributions and migratory movements are not well documented. From 2003-2007, we used GPS radio-collars to determine seasonal ranges and migration routes of 54 female caribou from the CAH. We calculated Brownian bridges to model fall and spring migrations for each year and used the mean of these over all 4 years to identify areas that were used repeatedly. Annual estimates of sizes of seasonal ranges determined by 90% fixed kernel utilization distributions were similar between summer and winter (X̅ = 27,929 SE = 1,064 and X̅ = 26,585 SE = 4912 km2, respectively). Overlap between consecutive summer and winter ranges varied from 3.3-18.3%. Percent overlap between summer ranges used during consecutive years (X̅ = 62.4% SE = 3.7%) was higher than for winter ranges (X̅ = 42.8% SE = 5.9%). Caribou used multiple migration routes each year, but some areas were used by caribou during all years, suggesting that these areas should be managed to allow for continued utilization by caribou. Restoring migration routes after they have been disturbed or fragmented is challenging. However, prior knowledge of movements and threats may facilitate maintenance of migratory paths and seasonal ranges necessary for long-term persistence of migratory species.

Taenia tapeworms of Finnish and Swedish wolves (Canis lupus) and Finnish brown bears (Ursus arctos), and muscle cysticerci of Svalbard reindeer (Rangifer tarandus platyrhynchus), Alaskan Grant's caribou (Rangifer tarandus granti) and Alaskan moose (Alces americanus) were identified on the basis of the nucleotide sequence of a 396 bp region of the mitochondrial cytochrome c oxidase subunit 1 gene. Two species were found from wolves: Taenia hydatigena and Taenia krabbei. The cysticerci of reindeer, caribou and one moose also represented T. krabbei. Most of the cysticercal specimens from Alaskan moose, however, belonged to an unknown T. krabbei-like species, which had been reported previously from Eurasian elks (Alces alces) from Finland. Strobilate stages from two bears belonged to this species as well. The present results suggest that this novel Taenia sp. has a Holarctic distribution and uses Alces spp. as intermediate and ursids as final hosts.

Reindeer (Rangifer tarandus tarandus) in Alaska are semidomestic livestock descended from 1280 animals introduced from Siberia, Russia, approximately 100 years ago. Genetic variation at 18 microsatellite DNA loci and the cytochrome b gene of mitochondrial DNA (mtDNA) was quantified in reindeer from Alaska, Siberia (Russia), and Scandinavia and compared with wild North American caribou. Mean sequence divergence among 15 mtDNA haplotypes in reindeer was 0.007 substitutions per nucleotide site, and reindeer mtDNA is polyphyletic with caribou mtDNA. Microsatellite allele and mtDNA haplotype frequencies are similar between Alaskan and Russian reindeer and differentiated between these and Scandinavian reindeer. The frequencies of microsatellite alleles and mtDNA haplotypes are different in reindeer and wild caribou (Rangifer tarandus granti, Rangifer tarandus groenlandicus, and Rangifer tarandus caribou). Alaskan reindeer have maintained a genetic variation comparable to that in Russia and differentiated from that of wild caribou, .100 years after their introduction to Alaska.

The Fortymile Caribou Herd (FCH) is the most prominent caribou herd in interior Alaska. A large portion of the FCH calving and summer range lies beneath heavily used Military Operations Areas (MOA) that are important for flight training. We observed the behavior of Grant's cow caribou (Rangifer tarandus granti) and their calves before, during, and immediately following low-level military jet overflights. We also monitored movements of radiocollared cow caribou and survival of their calves. We conducted fieldwork from mid May through early June 2002. We concluded that military jet overflights did not cause deaths of caribou calves in the FCH during the calving period nor result in increased movements of cow–calf pairs over the 24-hour period following exposure to overflights. Short-term responses to overflights were generally mild in comparison to caribou reactions to predators or perceived predators. Caribou responses to overflights were variable, but responses were generally greater as slant dis...

A large barren-ground caribou (Rangifer tarandus granti) population (the Bering Seacoast Herd) historically ranged across southwest Alaska. The size of this herd peaked in the early 1860s but declined by the late 1880s. Caribou numbers remained low in southwest Alaska for the next 100 years. Biologists have argued that periodic dispersal has been an important factor in caribou population dynamics. However, others conclude there was no credible evidence that significant interchange between herds has ever occurred in Alaska. Since 1981, we monitored 318 radiocollared caribou and documented dramatic population growth, erratic movements, shifts from traditional ranges, and changes in migratory behavior. We also documented shifts in calving distribution that may contrast with conventional concepts of calving tradition and herd identity. Some biologists have concluded caribou herds can be considered closed populations for management purposes because the number of dispersing caribou is so small that it has no influence on population dynamics. We propose that the current definition of a herd may be appropriate for short-term management; however, over long time frames and large spatial scales, metapopulations may better describe caribou ecology and be more useful in long-term caribou conservation.

Normal 0 21 false false false SV X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Normal tabell"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-fareast-language:EN-US;} Conservation and management of Alaska’s caribou ( Rangifer tarandus granti ) herds are important for ecological, cultural, social, and economic reasons. While most research is directed towards the large migratory herds, smaller herds that may or may not be migratory can be an equally valuable component of the state’s faunal resources; but for many of these smaller herds, basic information on herd size, demographics, space use and movements is lacking. We compiled Very High Frequency (VHF) telemetry data collected from 1994 - 2009 on 2 such herds in central Alaska, the Hodzana Hills Herd (HHH) and the Ray Mountain Herd (RMH) and estimated abundance, survival, resource selection and seasonal home ranges to inform future management of these herds. We found that both herds were relatively small and stable with approximately 1000 – 1500 individuals; annual survivorship of adult females was high (93% and 94% for RMH and HHH, respectively) and comparable to other stable or increasing herds in Alaska. Both herds were non-migratory maintaining seasonal ranges with substantial overlap. Additionally, despite their close proximity, we did not document any exchange of individuals between the 2 herds. Their spatial separation may be partly due to a strip of non-preferred habitat that somewhat parallels the Dalton Highway. While the telemetry data we used were not originally collected for the purpose of this study, careful compilation and application of appropriate analytical techniques allowed us to glean important characteristics of these herds that will be of value to regulatory and management agencies in the future. Normal 0 21 false false false SV X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Normal tabell"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-fareast-language:EN-US;}

"Livelihood systems that depend on mobile resources must constantly adapt to change. For people living in permanent settlements, environmental changes that affect the distribution of a migratory species may reduce the availability of a primary food source, with the potential to destabilize the regional social-ecological system. Food security for Arctic indigenous peoples harvesting barren ground caribou (Rangifer tarandus granti) depends on movement patterns of migratory herds. Quantitative assessments of physical, ecological, and social effects on caribou distribution have proven difficult because of the significant interannual variability in seasonal caribou movement patterns. We developed and evaluated a modeling approach for simulating the distribution of a migratory herd throughout its annual cycle over a multiyear period. Beginning with spatial and temporal scales developed in previous studies of the Porcupine Caribou Herd of Canada and Alaska, we used satellite collar locations to compute and analyze season-by-season probabilities of movement of animals between habitat zones under two alternative weather conditions for each season. We then built a set of transition matrices from these movement probabilities, and simulated the sequence of movements across the landscape as a Markov process driven by externally imposed seasonal weather states. Statistical tests showed that the predicted distributions of caribou were consistent with observed distributions, and significantly correlated with subsistence harvest levels for three user communities. Our approach could be applied to other caribou herds and could be adapted for simulating the distribution of other ungulates and species with similarly large interannual variability in the use of their range."

Caribou ( Rangifer tarandus granti ) use lichens, when available, as primary forage on their winter range. In boreal forest habitats, wildland fires effectively destroy lichens, and overwintering caribou are known to avoid burned areas for decades while lichen communities regenerate. However, little has been published about caribou response to burned habitat in tundra ecosystems. To assess the relationship between winter caribou distribution and burned areas, we instrumented Western Arctic Herd caribou with satellite telemetry collars and evaluated their locations in relation to recent burns of known age (? 55 years old) across northwestern Alaska. We analyzed caribou distribution for different habitat types (tundra and boreal forest), age categories of burns, and possible edge effects. We also reanalyzed the data, limiting available habitat to a uniform traveling distance (5658 m) from daily satellite locations. Using selection indices that compared caribou use of burns and buffers to their availability, we found that caribou strongly selected against burned areas within the tundra ecosystem. Recent burns were selected against at both large (range-wide) and intermediate (5658 m) spatial scales. Caribou particularly selected against 26- to 55-year-old burns and the interior (core) portions of all burns. We found that caribou were more likely to select burned areas in the late fall and early spring than midwinter. Increased fires in northwestern Alaska could decrease the availability and quality of winter habitat available to the herd over the short term (up to 55 years), potentially influencing herd population dynamics and reducing sustainable harvest levels. We recommend that fire managers consider caribou midwinter range condition and extent: however, management that achieves a mosaic pattern of fire history may benefit a wide array of species, including caribou. A better understanding of the current regional fire regime and the distribution of available winter range will be required before practicable management recommendations can be developed for this herd.

The population of the Western Arctic Herd, estimated at 490 000 caribou (Rangifer tarandus granti) in 2003, is at its highest level in 30 years. Twenty permanent range transects were established in the winter range of the Western Arctic Herd in 1981 to assess the impacts of grazing. These transects were revisited in 1995 and 1996 (1995/96). Only 18 of the transects were re-located, so an additional 7 transects were established in 1996. In 2005, all 25 remaining transects were revisited. Lichen coverage dropped by a relative 45.1% between 1981 and 1995/96 and by an additional relative 25.6% between 1995/96 and 2005. There was a significant decline in primary forage lichens between 1995/96 and 2005. Caribou use was greater in areas with high lichen abundance. Graminoid cover increased by a relative 118.4% from 1981 to 1995/96 and again by a relative 26.1% from 1995/96 to 2005. Shrub cover increased during the study whereas forb cover declined. The decline in lichen abundance on the winter range of the Western Arctic Herd over 24 years is an index of caribou habitat condition. The observed changes in vegetation cover can be attributed to caribou grazing, fire, and possibly global climate change. Continued declines in lichen cover could lead to population declines within the herd, range shifts, or both.

In this study, we develop a method to analyse the relationships between seasonal caribou distribution and climate, to estimate how climatic conditions affect interactions between humans and caribou, and ultimately to predict patterns of distribution relative to climate change. Satellite locations for the Porcupine (Rangifer tarandus granti) and Bathurst (R. t. groenlandicus) caribou herds were analysed for eight ecologically-defined seasons. For each season, two levels of a key environmental factor influencing caribou distribution were identified, as well as the best climate data available to indicate the factor's annual state. Satellite locations were grouped according to the relevant combination of season and environmental factor. Caribou distributions were compared for opposing environmental factors; this comparison was undertaken relative to hunting access for the Porcupine Herd and relative to exposure to mining activity for the Bathurst Herd. Expected climate trends suggest an overall increase in access to Porcupine caribou for Aklavik (NWT) hunters during the winter and rut seasons, for Venetie (Alaska) hunters during midsummer and fall migration and for Arctic Village (Alaska) during midsummer. Arctic Village may experience reduced availability with early snowfalls in the fall, but we expect there to be little directional shift in the spring migration patterns. For the Bathurst Herd, we expect that fewer caribou would be exposed to the mines during the winter, while more caribou would be exposed to the combined Ekati and Diavik mining zone in the early summer and to the Lupin-Jericho mining zone during the fall migration. If changes in climate cause an increased presence of caribou in the mining sites, monitoring and mitigation measures may need to be intensified.

Although historic literature is replete with anecdotes about atypical and far-reaching movements of caribou (Rangifer tarandus granti) herds in Alaska, very few such events have been described since the late 1970s proliferation of radiotelemetry studies in the region. In September 1992, several herds in Alaska made unusual movements away from their typical year-round ranges as a result of highly unusual weather conditions that affected a broad swath of the state. We describe the movements of 113 radiocollared caribou from the Denali caribou herd during this phenomenon and the subsequent year. The majority of caribou in the Denali Herd left their typical range during 26—28 September 1992, traveling distances up to 221 km and remained out of the area through much of the winter. While the outmigration was highly consolidated and easily noticed, the return was protracted with caribou drifting back to their typical range from October 1992 to early September 1993. All radiocollared caribou that survived the 1992—93 winter ultimately returned to their typical year-round range.

A generalized least squares regression model was developed to estimate local harvest of the Western Arctic caribou (Rangifer tarandus granti) herd. This model provides herd and community level harvest based on community size, proximity of the herd to the village. The model utilizes community harvest survey information from the Alaska Department of Fish and Game, Subsistence Division and cooperation from the nonprofit organizations Maniliq and Kawerak. The model will assist in an annual selection of communities to survey. The predicted local resident harvest of the Western Arctic caribou herd is 14 700 with 95% lower and upper confidence limits of 10 100 and 19 700 respectively.

Barren ground caribou (Rangifer tarandus granti) of the Teshekpuk Caribou Herd (TCH) inhabit the western portion of Alaska's Arctic Coastal Plain within the National Petroleum Reserve—Alaska (NPR-A). Alaska's North Slope communities, management agencies, and private industry are interested in this herd because of its importance as a subsistence resource and location relative to potential petroleum development. From 1998 through 2000, we monitored caribou distribution during the calving period within the Northeast Planning Area of the NPR-A using systematic strip-transect aerial surveys, as well as VHF and satellite telemetry for cow caribou. Aerial survey and telemetry data indicated cows with calves were distributed around Teshekpuk Lake, with a concentration south of the lake in 1999 and 2000. Inconsistencies in weather conditions, survey timing (both strip-transect and VHF surveys), 100% coverage survey areas, and small sample sizes confound interpretations of our results. However, several patterns were apparent. Later transect survey timing (7—12 June versus 4—7 and 5—8 June) resulted in more cow/calf pairs recorded. Our 18% coverage area, originally based on VHF telemetry data for the extent of TCH calving, covered a consistently high proportion (95% to 100%) of the annual calving ranges (95% kernel utilization distributions), but accounted for only 24% to 46% of the adult cows in the TCH based on the current Alaska Department of Fish and Game population estimate (1999) and average 1998¬2000 herd composition. It appears that either our transect survey methodology significantly underestimated the true number of caribou cows in the study area, many cows calved outside the area or moved into the area and calved after our surveys, or we have over estimated the number of reproductive cows in the herd. Our 100% coverage transect areas covering oil and gas lease areas, contained 38% of the calving range with 23% of TCH cows in 1999; and 18% of the calv¬ing range with 8% of TCH cows in 2000. Based on 95% minimum convex polygon ranges, satellite collared cow/calf pairs were not stationary during either our survey period (14.7 ± 6.56 km2; mean ± standard error of the mean; 4—12 June) or during the calving period (86.9 ± 72.30 km2; 1—20 June) during 1998—2000. Site specific pre-development data on caribou distribution during calving in NPR-A will be useful for assessing the importance of specific areas to caribou during calving and for designing oilfields that minimize impacts should oil development occur.

We studied natality in the Northern Alaska Peninsula (NAP) and Southern Alaska Peninsula (SAP) caribou (Rangifer tarandus granti) herds during 1996-1999, and mortality and weights of calves during 1998 and 1999- Natality was lower in the NAP than the SAP primarily because most 3-year-old females did not produce calves in the NAP Patterns of calf mortality in the NAP and SAP differed from those in Interior Alaska primarily because neonatal (i.e., during the first 2 weeks of life) mortality was relatively low, but mortality continued to be significant through August in both herds, and aggregate annual mortality was extreme (86%) in the NAP Predators probably killed more neonatal calves in the SAP, primarily because a wolf den (Canis lupus) was located on the calving area. Despite the relatively high density of brown bears (Ursus arctos) and bald eagles (Haliaeetus leucocephalus), these predators killed surprisingly few calves. Golden eagles (Aquila chrysaetos) were uncommon on the Alaska Peninsula. At least 2 calves apparently died from pneu¬monia in the range of the NAP but none were suspected to have died from disease in the range of the SAP. Heavy scav¬enging by bald eagles complicated determining cause of death of calves in both the NAP and SAP.

The five naturally occurring and one transplanted caribou (Rangifer tarandus granti) herd in southwestern Alaska composed about 20% of Alaska's caribou population in 2001. All five of the naturally occurring herds fluctuated considerably in size between the late 1800s and 2001 and for some herds the data provide an indication of long-term periodic (40-50 year) fluctuations. At the present time, the Unimak (UCH) and Southern Alaska Peninsula (SAP) are recovering from population declines, the Northern Alaska Peninsula Herd (NAP) appears to be nearing the end of a protracted decline, and the Mulchatna Herd (MCH) appears to now be declining after 20 years of rapid growth. The remaining naturally occurring herd (Kilbuck) has virtually disappeared. Nutrition had a significant effect on the size of 4-month-old and 10-month-old calves in the NAP and the Nushagak Peninsula Herd (NPCH) and probably also on population growth in at least 4 (SAP, NAP, NPCH, and MCH) of the six caribou herds in southwestern Alaska. Predation does not appear to be sufficient to keep caribou herds in southwestern Alaska from expanding, probably because rabies is endemic in red foxes (Vulpes vulpes) and is periodically transferred to wolves (Canis lupus) and other canids. However, we found evidence that pneumonia and hoof rot may result in significant mortality of caribou in southwestern Alaska, whereas there is no evidence that disease is important in the dynamics of Interior herds. Cooperative conservation programs, such as the Kilbuck Caribou Management Plan, can be successful in restraining traditional harvest and promoting growth in caribou herds. In southwestern Alaska we also found evidence that small caribou herds can be swamped and assimilated by large herds, and fidelity to traditional calving areas can be lost.

Large mammalian herbivores introduced to islands without predators are predicted to undergo irruptive population and spatial dynamics, but only a few well-documented case studies support this paradigm. We used the Riney-Caughley model as a framework to test predictions of irruptive population growth and spatial expansion of caribou (Rangifer tarandus granti) introduced to Adak Island in the Aleutian archipelago of Alaska in 1958 and 1959. We utilized a time series of spatially explicit counts conducted on this population intermittently over a 54-year period. Population size increased from 23 released animals to approximately 2900 animals in 2012. Population dynamics were characterized by two distinct periods of irruptive growth separated by a long time period of relative stability, and the catalyst for the initial irruption was more likely related to annual variation in hunting pressure than weather conditions. An unexpected pattern resembling logistic population growth occurred between the peak of the second irruption in 2005 and the next survey conducted seven years later in 2012. Model simulations indicated that an increase in reported harvest alone could not explain the deceleration in population growth, yet high levels of unreported harvest combined with increasing density-dependent feedbacks on fecundity and survival were the most plausible explanation for the observed population trend. No studies of introduced island Rangifer have measured a time series of spatial use to the extent described in this study. Spatial use patterns during the post-calving season strongly supported Riney-Caughley model predictions, whereby high-density core areas expanded outwardly as population size increased. During the calving season, caribou displayed marked site fidelity across the full range of population densities despite availability of other suitable habitats for calving. Finally, dispersal and reproduction on neighboring Kagalaska Island represented a new dispersal front for irruptive dynamics and a new challenge for resource managers. The future demography of caribou on both islands is far from certain, yet sustained and significant hunting pressure should be a vital management tool.

Elevated oil field pipelines may alter Caribou (Rangifer tarandus granti) movements and delay or prevent access to insect relief habitat. In an attempt to determine if the 40-km elevated Badami pipeline in northern Alaska changed Caribou use of riparian habitats at the three river crossings where the pipeline is buried, we quantified Caribou habitat use at all three crossings using time-lapse video cameras and aerial distribution surveys over three summers. We compared habitat use, behavior and duration of observations among pipeline and non-pipeline sites. We used a block experimental design with cameras at four sites at the three river crossings to evaluate differences in numbers of Caribou per day at pipeline and non-pipeline sites. At each crossing, four cameras were positioned, with one pair of cameras next to the pipeline (pipeline sites) and one pair of cameras 1.8-3.2 km upstream from the pipeline (non-pipeline sites); where cameras monitored the river bank and channel (river habitat) and the tundra within about 200 m of the river (tundra habitat). Peak numbers of Caribou per day occurred during early July 2003 and mid-July 2001 and 2002. Large numbers of Caribou recorded north of the pipeline during aerial surveys did not usually correspond with increased number per day recorded by cameras suggesting Caribou probably also crossed the pipeline outside of the riparian areas. We assessed local changes in riparian habitat use by comparing the numbers of Caribou per day in river and tundra habitats at pipeline and non-pipeline sites and found no difference. We assessed regional changes in riparian habitat use by comparing numbers of Caribou per day at pipeline sites and at non-pipeline sites and found no difference. Caribou groups spent an average of 1 minute longer at tundra pipeline sites and groups spent 30 seconds longer feeding and trotting at pipeline sites, but these differences were not significant.

During fall and winter 1994—1995 and winter 1999—2000, caribou (Rangifer tarandus granti) from the Western Arctic Herd experienced high, localized mortality in northwest Alaska near Cape Thompson. Substantial numbers of caribou wintered in this area during 1986—1987, 2001—2002, and 2002—2003 without suffering high mortality. During the 1994—1995 event, 2000 to 3000 caribou died out of roughly 10 000 that wintered in this area. About 4000 caribou perished out of approximately 20 000 that wintered here during 1999—2000. During both mortality events, gross characteristics and tissue analyses indicated caribou in this area were malnourished. Weather near Cape Thompson during winter 1994—1995 was colder, windier, and had more snow than other years when caribou wintered in this area; in contrast, conditions during 1999—2000 were not unusually severe. Additionally, Cape Thompson experienced 2—5 occurrences of severe conditions during winter 1994—1995 while 1999—2000 experienced only 1 such occurrence at most. Several indicators suggested severe storms killed some caribou before starvation was fatal. Cape Thompson consistently experienced higher wind, lower ambient air temperature, and shallower snow cover than other portions of winter range used by this herd. Unlike years when caribou wintered in this area without experiencing high mortality, caribou were in relatively poor body condition during the autumn that preceded each die-off. Although these mortality events were inconsequential to size of this caribou herd, they raised local residents' concerns that contaminants had poisoned caribou and possibly jeopardized human health. Muskoxen (Ovibos moschatus) in this area were not affected by weather or snow conditions during either caribou mortality event.

We examined the distribution and movements of 141 radiocollared female caribou (Rangifer tarandus granti) of the Central Arctic Herd during summer, 1980-1993. Numbers of caribou locations within each of 5 quadrats along the arctic coast were totalled separately for days during which insects were active and inactive, and numbers of east-west and west-east crossings of each quadrat mid-line were determined from sequential observations. Both abundance and lateral movements of radiocollared females in the quadrat encompassing the intensively-developed Prudhoe Bay oilfield complex were significantly lower than in other quadrats (P < 0.001 and P < 0.00001, respectively). Avoidance of, and fewer movements within, the complex by female caribou are ostensibly in response to the dense network of production and support facilities, roads, above-ground pipelines, and the associated vehicular and human activity. Impaired access to this area constitutes a functional loss of habitat.

Concerns have been raised that displacement from traditional calving and postcalving areas by petroleum exploration may cause increased calf mortality in the Porcupine Caribou (Rangifer tarandus) Herd. Consequently, we determined productivity and early calf survival by frequently locating 23-53 radio-collared cows and 59-61 radio-collared calves from 1983 to 1985. Seventy-nine to 87% of the adult females gave birth each year, and 68-90% of calves were born within, or adjacent to, a coastal plain area proposed for petroleum leasing and development. Sixteen to 35% of the calves died by 25 June. Fifty-nine to 74% of calf mortality occurred within 48 hours of birth and involved a number of causes in addition to predation. Predation was the major cause of death after the first 48 hours, and mortality increased toward higher terrain away from the coastal plain

A resident herd of caribou (Rangifer tarandus granti) inhabits the Koyukuk River valley and Kokrines Hills, which are located on the north side of the Yukon River near the Alaskan villages of Galena and Ruby. Personnel from the Alaska Departement of Fish and Game, U.S. Bureau of land Management, and U.S. Fish and Wildlife Service studied this herd from October 1983 to January 1990. The highest caribou count was 258 in June 1987. The proportion of newborn calves observed during the May calving period ranged from 0 to 28% (mean=10%) whereas it ranged from 4 to 17% (mean=13%) in October. Caribou inhabited mostly coniferous forest from October through April and open habitat from May through September. Male caribou occupied fewer habitat types, travelled less distance, and remained at lower elevations than female caribou. Management concerns for this herd are discussed.

FANCY, S. G., PANK, L. F., WHITTEN, K. R., and REGELIN, W. L. 1989. Seasonal movements of caribou in arctic Alaska as determined by satellite. Can. J. Zool. 67: 644 -650. Between 1985 and 1987, 49 283 locations and 79 101 sets of activity data were obtained for 34 adult female caribou (Rangifer tarandus granti) of the Porcupine and Central Arctic herds using satellite telemetry. Daily movement rates of female caribou from the two herds, which differ greatly in size and separation of seasonal ranges, were similar except during the spring and fall migration periods. Movement rates in July exceeded those during migration in both herds. The minimum annual distances travelled by caribou cows, ranging to 5055 km, were the longest movements documented for any terrestrial mammal.

Intensive petroleum-related development on Alaska's Arctic Slope is not always compatible with the habitat requirements of barren-ground caribou ( Rangifer tarandus granti ). Surface alteration can result in displacement of caribou from previously occupied components of range. Although, to date, losses of habitat have been localized, apparently with no adverse effects on herd productivity, uncontrolled or improperly planned future development on state and federal lands could remove large areas of caribou habitat, with potentially serious consequences to all of the arctic herds. Caribou represent a valuable recreational and subsistence resource. State and federal land management agencies must fully acknowledge the potential conflicts associated with industrial activity and adopt conservative policies of subsurface leasing and surface development. Key words: caribou, petroleum development, disturbance, Alaska

In winter 1981 - 82, a 29-km road system was built in a high-use caribou (Rangifer tarandus granti) calving area near Milne Point, Alaska. Aerial surveys of this area were conducted annually during the calving period for 4 years before and 4 years after road construction. Effects of the road system on the distribution of caribou were investigated by comparing survey data obtained during these two periods. The 41 400-ha study area was partitioned into 40 quadrats; after construction (1982 - 85), significantly fewer caribou were observed within quadrats encompassing the present road system than before construction (1978 - 81). The area within 6 km of the road system was stratified into six 1-km intervals, and differences in the distribution of caribou among those strata were examined using linear regression analysis. After construction, the density of maternal females was positively correlated with distance, whereas no such relationship was apparent before construction. Density of nonmaternal adults was unrelated to distance during both periods. The results suggest that a local displacement of maternal caribou has occurred in response to roads and associated human activity.

The Steese-Fortymile caribou (Rangifer tarandus granti) herd has changed its calving distribution frequently during the past 30 years. A «traditional» calving area, used for decades, west of the Steese Highway (Preacher Creek) was abandoned after 1963. By the early 1970's, a new calving area had been established 74 km to the southeast in the Birch Creek drainage. This new calving area was abandoned after 1976. From 1977 through 1983, calving occurred in annually variable locations approximately 136 km southeast of the Birch Creek calving area. In 1984, however, the herd again calved in the general vicinity of the Birch Creek calving area. General characteristics of the various calving areas are described, and calving distribution is discussed in relation to herd size, development and disturbance, predator abundance, and other factors. Location of calving in recent years was unpredictable, which warrants reconsidering the merit of protecting only previously important calving grounds.

Movements and activity patterns were compared for caribou ( Rangifer tarandus granti ) near two active drilling sites on the periphery of the Prudhoe Bay oilfield and for caribou from a control site. Caribou on the experimental and control sites had similar movement rates and activity budgets, but many localized responses to the roads, pipelines, vehicle traffic, and other structures and activities were observed. Insect harassment had an appreciable effect on caribou movements and activity budgets. Groups harassed by insects moved approximately twice as fast and spent at least 50% less time lying and feeding than did unharassed groups. Of the 99 groups that approached a road, pipeline, and/or drill site, 70.7% crossed directly, 19.2% detoured around the drill site, and 10.1% reversed direction and left the study area. No evidence was found that caribou cows and calves were avoiding the area because of drilling operations. Key words: caribou, Rangifer tarandus granti , movements, disturbance, insect harassment, Prudhoe Bay, petroleum development

Two large groups of mosquito-harassed caribou ( Rangifer tarandus granti ) were followed for 8-12 h as they repeatedly attempted to cross an elevated pipeline in the Kuparuk Development Area near Prudhoe Bay, Alaska. In 1981, 46% of a group of 917 eventually crossed beneath elevated portions of the pipeline in 26 separate attempts, 13% crossed a section of buried pipe in two attempts, 22% trotted parallel to the pipeline for 32 km and did not cross, and 19% separated from the group and were not accounted for. In 1982, 26% of a group of 655 crossed under elevated portions of the pipeline in 36 attempts, 37% crossed at a buried section in one attempt, and 37% left the main group and could not be accounted for. The majority of crossing attempts occured near intersections of lakes with the road/pipeline complex, but crossing success was highest at a section of buried pipe isolated from the road traffic. Key words: caribou, pipeline, petroleum development, insect harassment, Kuparuk Oil Field

The Delta and Yanert caribou (Rangifer tarandus granti) herds apparently maintained discrete calving areas from 1979 through 1983 (as determined by radio telemetry studies), even though substantial intermixing occurred during other seasons. Also, the Delta herd apparently used a single traditional calving area from the 1950's through 1983, based on results of aerial surveys and 1979-83 telemetry studies. Calving distribution in 1984 changed dramatically; 5 of 25 radio-collared Delta herd cows ^3 years old and 5 of 24 radio-collared Delta herd cows

There was an unusual increase in numbers of caribou (Rangifer tarandus granti) in the Central Arctic region of Alaska from 1981 to 1985. In fall and winter numbers were up to five times greater than at the onset of calving in June. Numbers appeared to double during the month of June each year, then remain relatively stable over the summer period with a further increase in the fall. Ingress of caribou from outside the region in fall was observed in all years and egress in the early spring is postulated. We conclude that a small resident herd inhabits the region year round with numbers increasing through ingress of caribou from the Western Arctic herd possibly beginning as early as June. Increases or decreases in the size of adjacent herds probably will affect the numbers of caribou occupying the Central Arctic region.

Estimates of the energy costs of resting, activity, and productive processes from the literature were applied to caribou activity budgets and movements documented during 1978-80 to estimate seasonal and annual energy requirements of adult female caribou (Rangifer tarandus granti) in Denali National Park and Preserve. Energy requirements were 45% lower in winter than summer, primarily because of a 21% reduction in resting metabolic rate and benefits of fat catabolism in winter, and high summer costs of lactation, fat deposition, and activity. Estimated energy requirements totaled 38.2 MJ . day-' during the insect season, 36.7 during summer migration, 34.2 during fall migration, 31.9 during prerut and rut, 29.3 during calving and postcalving, 23.7 during early and late winter migrations, 21.6 during early winter, 20.9 during late winter, and 20.5 during midwinter. Annual energy requirements, including costs of pregnancy (368.6 MJ) and lactation (560.3), totaled 9,870 MJ, excluding costs of cratering through snow and apparently minor costs of physiological stress. Compared to studies of food energy requirements of penned caribou, the model gives accurate predictions of total metabolizable energy requirements when allowances are made for the relative inactivity of penned animals. Modeling the energy requirements of an ungulate population is a prerequisite to estimating nutritional carrying capacities (Moen 1973, Robbins 1973, Wallmo et al. 1977, Mautz 1978). Measurements of the energy requirements of Rangifer have received emphasis in several studies (Makarova and Segal 1958, Hammel et al. 1961, Segal 1962, McEwan 1970, Luick et al. 1974, Young and McEwan 1975, White and Yousef 1978), but these measurements have not previously been used to model seasonal energy requirements of a caribou/ reindeer (Rangifer tarandus) population. Author is game research biologist, Alaska Department of Fish and Game, 1300 College Road, Fairbanks, Alaska 99701. At the time of the research, author was graduate student, Alaska Cooperative Wildlife Research Unit, University of Alaska, Fairbanks. Financial and logistical support was provided by the U.S. National Park Service (contract CX-9000-7-E080). Manuscript accepted May 28, 1985. Thomson (1977) attempted to model the year-round energy expenditure of wild reindeer in Norway using estimates of energy expenditure from the literature. However, Thomson's applications of energy costs differed in several ways from those presented here, making comparisons difficult. The most significant deviations included Thomson's exclusion of estimates for the calorigenic effect of food and his extremely high estimate for the energy cost of trotting. Gaare et al. (1975) also estimated seasonal energy requirements of wild reindeer in Norway. However, their estimates are about 45% of those reported here. Since they did not present energy-cost estimates of the various activities, it is impossible to account for the difference. White et al. (1975) estimated the summer energy requirements for caribou activity as simply 2 X basal metabolic rate (BMR). However, they used a winter-BMR value, so their summer energy estimates are substantially lower than presented here. I studied the Denali (formerly McKinley) caribou herd in Denali National Park and Preserve, Alaska during 1978-80. A model of the nutritional ecology of the herd was developed to assess the energetic/ nutritional status of this extremely reduced population (Boertje 1981). This paper demonstrates the applicability of measurements of energy costs by modeling metabolizable energy requirements of adult female caribou in the Denali herd.