Wild Caribou Research Articles

Securing the boundaries of wilderness in northern Alaska, 1892–1950

This paper examines the socio-ecological implications of reindeer-caribou hybridization during the rise and collapse of the reindeer industry in Alaska. Following their introduction in the late nineteenth century, reindeer populations increased dramatically as herds spread throughout the territory. As populations increased, domesticated reindeer often escaped from their herds and ran off with migratory caribou. By the 1920s, Alaskan wildlife managers and scientists came to view feral reindeer as a form of biological pollution and a threat to the health and purity of the region's wild caribou. Despite divergent evolutionary histories, reindeer and caribou are related at the subspecies level and can interbreed to produce hybridized offspring. I argue that managerial anxieties about reindeer-caribou hybridization were bound up with broader concerns regarding race and related efforts to protect ostensibly pure spaces of wilderness and nature. Throughout the paper, I consider managerial attempts to mitigate reindeer-caribou hybridization in northern Alaska, which included the demarcation and reinforcement of conceptual and spatial boundaries between wild and domesticated forms of life. However, between the late nineteenth and mid-twentieth centuries, feral reindeer and hybridized caribou repeatedly demonstrated the violability of the biological categories and conceptual boundaries that wildlife managers employed as they sought to order life on the northern tundra.

Novel multilayer network analysis to assess variation in the spatial co-occurrences of close kin in wild caribou populations

Understanding how individuals within populations are connected genetically and through shared space-use is critical to understanding the demographic patterns of at-risk populations. In recent years, non-invasive genetic sampling methods have allowed us to begin addressing these questions. Using a network analysis framework, we examined the spatial co-occurrence and genetic relatedness of boreal and central mountain caribou (Rangifer tarandus) in populations varying in sizes and trend from across western Canada. Using 15 microsatellites loci and a sex-specific marker, we developed pedigree networks for each population, including first to third order relationships. We constructed networks of individual spatial co-occurrence, and using multilayer network analysis, we determined the degree to which caribou that co-occurred spatially were related. Caribou populations varied in the extent and classes of familial relationships which co-occurred in space. In most populations, spatial co-occurrences were greater than expected only for parent-offspring relationships. A sex-specific analysis of the longest sampled population revealed that this was driven by a significant overlap between mothers and their offspring. Whereas in populations where very few parent-offspring relationship were detected, no significant overlap was found between any relationship categories. The lack of overlap in these populations may be an indication of poor calf survival. On the other hand, the higher degree of overlap with more distant relations (i.e., grandparents) seen in some populations may indicate a population that lacks mobility. Our research presents a new approach to explore both spatial and genetic overlap at the individual level in support of the conservation of threatened populations.

Animal‐defined resources reveal nutritional inadequacies for woodland caribou during summer–autumn

AbstractPopulations of woodland caribou (Rangifer tarandus caribou) are declining throughout their range and many are at risk of extirpation, yet the role of nutrition in these declines remains poorly understood, in part owing to a lack of information about available nutritional resources during summer. We quantified rates of intake of digestible protein and digestible energy by tame caribou foraging in temporary enclosures in the predominant plant communities of northeastern British Columbia, Canada, during summer–autumn and compared intake rates to daily requirements for protein and energy during lactation. We tested hypotheses related to the nutritional adequacy of the environment to support nutritional requirements during lactation (with and without replenishment of body reserves) and simulated scenarios of foraging by caribou in these plant communities to better understand how wild caribou could meet nutritional demands on these landscapes. Nutritional resources varied among plant communities across seasonal, ecological, and successional gradients; digestible energy intake per minute and per day were significantly greater in younger than older forests; dietary digestible energy and per‐minute and daily intake of digestible protein were greater, though not significantly so, in younger than older forests; and dietary digestible protein was greater in older than younger forests, though differences were not significant. Tame caribou were unable to satisfy protein and energy requirements during lactation, even without replenishment of body reserves, at most sites sampled. Further, foraging simulations suggested widespread nutritional inadequacies on ranges of wild caribou. Selection for habitats offering the best nutrition may mitigate some nutritional inadequacies, but given low availability of vegetation communities with high nutritional value, performance (e.g., calf production, growth, replenishment of body fat and protein) of caribou may be depressed at levels of nutrition documented herein. Our results, coupled with recent measurements of body fat of wild caribou in northeastern British Columbia, refute the hypothesis that the nutritional environment available to caribou during summer in northeastern British Columbia is adequate to fully support nutritional demands of lactating caribou, which has implications to productivity of caribou populations, recovery, and conservation.

Evaluating indices of nutritional condition for caribou (Rangifer tarandus): which are the most valuable and why?

Body composition studies are critical for evaluating the accuracy of nutritional condition indices for predicting body components. We evaluated >40 indices of nutritional condition for caribou (Rangifer tarandus (Linnaeus, 1758)) using 29 female caribou captured from three populations in Alaska (USA) that ranged in condition from 2.3% to 11.2% ingesta-free body fat (IFBF) and 6 captive female caribou that ranged in condition from 8.1% to 26.0% IFBF. Estimates of body fat, protein, and gross energy were regressed against each index of nutritional condition. Generally, indices with linear or slightly curvilinear relations to body fat and those based on multiple fat depots were the most accurate in predicting nutritional condition and the most useful over the full range of nutritional condition. A scaledLIVINDEX (a combination of subcutaneous fat thickness and a condition score), CONINDEX (a combination of kidney fat and marrow fat), and a subset of the Kistner score (pericardium and kidneys only) had the strongest relationship with body fat (r2 > 0.86) and were useful over the entire range of nutritional condition. If used properly and with adequate training, indices of nutritional condition can be a critical tool for understanding the severity and seasonality of nutritional limitations in wild caribou populations.

Love and Death: Theoretical and Practical Examination of Human-Animal Relations in Creating Wild Animal Osteobiography

Abstract Osteobiographies are a common form of presenting the archaeological analysis of the life history of an individual. This form of analysis, however, is usually reserved for human subjects. Writing an osteobiography of a nonhuman person is complicated by the lack of human understanding of animal thought and experience. Such analysis is further complicated when the subject is not a companion animal, and isolated from human funerary rituals which may shed light on the animal’s life. The skeletal remains of an injured wild caribou from Alberta who was collected as a museum specimen presents a unique opportunity to understand an individual animal’s life, as well presents an example of the complexities of human-animal relationships in an analytical setting. This study examines both the life of an extraordinary nonhuman person and the impact of reconstructing nonhuman life histories on the analyst.

Top stories: last wild caribou in the lower 48, glowing brains, and ancient fossils under threat

Top stories: last wild caribou in the lower 48, glowing brains, and ancient fossils under threat

The contiguous United States just lost its last wild caribou

The contiguous United States just lost its last wild caribou

Five years of record warmth intensify Arctic's transformation

Sea ice is the thinnest it's been at any time in the last 30 years, and wild reindeer and caribou populations continue to decline. Sea ice was thinner in late 2017 and much of 2018 than at any time in the last 30 years, while wild reindeer and caribou populations continue to decline.

Reindeer introgression and the population genetics of caribou in southwestern Alaska.

Alaska caribou (Rangifer tarandus granti) in southwestern Alaska are a poorly understood system, with differing descriptions of their regional population structure, population abundance that has varied greatly through time and instances of the release of domestic reindeer (R. t. tarandus) into their range. Here, we use 21 microsatellites and 297 individuals to investigate the genetic population structure of herds and examine for population bottlenecks. Then, using genetic characteristics of existing reindeer populations, we examine introgression into the wild caribou populations. Caribou of the area are genetically diverse (H E between 0.69 and 0.84), with diversity decreasing along the Alaska Peninsula (AP). Using G ST and Jost's D, we find extensive structuring among all herds; Migrate-n finds that AP herds share few effective migrants with other herds, with Southern AP and Unimak Island herds having the least. Bayesian clustering techniques are able to resolve all but Denali and Mulchatna caribou herds. Using a conservative assignment threshold of q reindeer ≥ 0.2, 3% of caribou show signs of domestic introgression. Denali herd has the most introgressed individuals (6.9%); those caribou herds that were historically adjacent to smaller reindeer herds, or were historically without adjacent herding, show no admixture. This domestic introgression persists despite the lack of managed reindeer in the region since the 1940s. Our results suggest that despite previous movement data indicating metapopulation-like dispersal in this region, there may be unknown barriers to reproduction by dispersing individuals. Finally, our results support findings that wild and domestic Rangifer can hybridize and show this introgression may persist dozens of generations after domestics are no longer present.

Hand‐Rearing Wild Caribou Calves for Studies of Nutritional Ecology

Caribou (Rangifer tarandus) are considered difficult to hand-rear in captivity because they are sensitive to the composition and volume of formulated milks. We used a strict feeding schedule and a commercial milk formula designed specifically for caribou to bottle-feed neonates captured from five wild caribou herds in Alaska. Under a feeding protocol adjusted for age and mass, the growth rates and body mass of 26 hand-reared caribou calves to weaning were similar to those of three maternally nursed caribou. This protocol allows caretakers to hand-rear caribou that are as representative as possible of maternally raised neonates.

An isotopic approach to measuring nitrogen balance in caribou

AbstractNutritional restrictions in winter may reduce the availability of protein for reproduction and survival in northern ungulates. We refined a technique that uses recently voided excreta on snow to assess protein status in wild caribou (Rangifer tarandus) in late winter. Our study was the first application of this non‐invasive, isotopic approach to assess protein status of wild caribou by determining dietary and endogenous contributions of nitrogen (N) to urinary urea. We used isotopic ratios of N (δ15N) in urine and fecal samples to estimate the proportion of urea N derived from body N (p‐UN) in pregnant, adult females of the Chisana Herd, a small population that ranged across the Alaska‐Yukon border. We took advantage of a predator‐exclosure project to examine N status of penned caribou in April 2006. Lichens were the primary forage (>40%) consumed by caribou in the pen and δ15N of fiber tracked the major forages in their diets. The δ15N of urinary urea for females in the pen was depleted relative (−1.3 ± 1.0 parts per thousand [‰], ${\bar {x}}\pm {\rm SD}$) to the δ15N of body N (2.7 ± 0.7‰). A similar proportion of animals in the exclosure lost core body mass (excluding estimates of fetal and uterine tissues; 55%) and body protein (estimated by isotope ratios; 54%). This non‐invasive technique could be applied at various spatial and temporal scales to assess trends in protein status of free‐ranging populations of northern ungulates. Intra‐ and inter‐annual estimates of protein status could help managers monitor effects of foraging conditions on nutritional constraints in ungulates, increase the efficiency and efficacy of management actions, and help prepare stakeholders for potential changes in population trends. © 2010 The Wildlife Society.

Dermoid Cysts in Caribou

Subcutaneous dermoid cysts were identified in eight wild caribou (Rangifer tarandus) from widely dispersed locations in northern Canada and in one wild caribou from Alaska. The dermoid cysts from Canadian caribou were found among 557 diagnostic specimens that had been detected by hunters and submitted by resource officers and biologists between 1 January 1966 and 15 May 2007. All of the cysts were located in the cervical region, and five of nine cysts were found in the throat area. All of the animals for which the age was known were adult; males and females were equally represented. Dermoid cysts were not diagnosed in any of 1,108 white-tailed deer (Odocoileus virginianus), 293 mule deer (Odocoileus hemionus), 174 elk (Cervus elaphus), or 529 moose (Alces alces) examined during the same period at the Canadian laboratory.

Reindeer Herding in Transition: Historical and Modern Day Challenges for Alaskan Reindeer Herders

Abstract The people of northwestern Alaska have had a long relationship with local populations of Rangifer tarandus. During the last 200 years this relationship has changed from one of subsistence to overexploitation of caribou (the name for wild reindeer in North America), to commercial livestock production of semi domesticated reindeer and now may be returning to a subsistence economy based on caribou. Reindeer were introduced to Alaska in 1892 because of the disappearance of caribou, a subsistence resource. Until recently, reindeer meat and velvet antler production generated significant employment and revenue important to the economies of rural Alaskan communities. However, from 1976 to 1996 the Western Arctic Caribou Herd (WACH) increased from about 75,000 to 463,000 animals. Concurrently, winter range use of the WACH shifted westward onto traditional reindeer ranges of the Seward Peninsula for the first time in over 100 years. This event has produced socio-economic and ecological consequences for the region. Many reindeer herders have lost 75-100 percent of their herds through commingling and out-migration with wild caribou. This loss, amounting to over 17,000 reindeer, represents a potential economic value of millions of dollars. Many herders have adopted new technologies, such as satellite telemetry and intensive herding to salvage what is left of their herds. Here we discuss the role of grazing animals and patterns of human resource use in an Arctic system. We then discuss our findings on the effects and changes in management practices brought about by caribou incursion in the context of the regional economy on the Seward Peninsula.

Mitochondrial DNA and Microsatellite DNA Variation in Domestic Reindeer (Rangifer tarandus tarandus) and Relationships with Wild Caribou (Rangifer tarandus granti, Rangifer tarandus groenlandicus, and Rangifer tarandus caribou)

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.

Research on deer taxonomy and its relevance to management

Taxonomic classifications are based on phylogenetic relationships, which can be inferred from paleontological, morphological, or genetic data. In this paper, I describe recent molecular genetic data that contribute to the understanding of taxonomic and phylogenetic relationships of the Cervidae at the family, species, subspecies, and population levels. At higher taxonomic levels, the relationships of cervids have been inferred from several molecular genetic markers. Mitochondrial DNA and nuclear DNA sequences (e.g., casein genes) have been used to infer the relationships of Cervidae to other artiodactyl families and the relationships among cervid subfamilies, genera, and species. The data used in such analyses can be extended to practical management applications such as forensic species identification. DNA sequences and allele frequencies of proteins and microsatellite loci can also be used to infer relationships among congeneric species, subspecies, and populations. Understanding relationships at these lower taxonomic levels is useful in several management contexts. Species relationships are important in cases where interspecific competition or hybridization may be important, as with white-tailed deer (Odocoileus virginianus) and mule deer (O. hemionus) in western North America. Quantification of the genetic differentiation among subspecies and populations is useful for identification of management units and inference of the extent of common ancestry and gene flow. Caribou (Rangifer tarandus granti) and domestic reindeer (R. t. tarandus) are discussed as an example of subspecies that remain genetically differentiated 110 y after the introduction of domestic reindeer to wild caribou ranges in Alaska. Genetic data also show that four wild caribou herds in Arctic Alaska comprise one interbreeding population, although each herd has a different calving range. The concepts of subspecies, populations, and other intra-specific taxa are discussed.

Conflicts between reindeer herding and an expanding caribou herd in Alaska

The reindeer industry has existed in Alaska since 1892. This industry has largely been concentrated on the Seward Peninsula, Alaska because suitable habitat has been available and caribou have been absent here for over 100 years. Until recently, reindeer meat and velvet antler production consistently generated millions of dollars in revenue critical to the economies of rural Alaskan communities. From 1976 to 1996 the Western Arctic Caribou Herd (WACH) increased from about 75 000 to 463 000 animals. Concurrently, seasonal range use of the WACH shifted westward onto traditional reindeer ranges of the Seward Peninsula. Reindeer herders lost 75-100% of their herds through commingling and out¬migration with wild caribou. This loss of over 12 000 reindeer represents a potential economic value of 13 million dollars. Sustainable meat and velvet antler production and the economies of western Alaskan are likely to be affected by these changes.

Ceruloplasmin as an indicator of copper reserves in wild ruminants at high latitudes.

Northern ungulates must establish trace mineral reserves when forage is available in spring and summer to sustain biochemical activities through the long winter. Copper (Cu), zinc (Zn) and iron (Fe) reserves were measured in the serum, digestive tract, liver, and kidney of six male caribou and reindeer (Rangifer tarandus) fed a complete pelleted ration. Dry matter content and absolute amounts of Cu, Zn and Fe were highest in the liver. Digesta contents of Cu and Zn were greatest in the rumen but dry matter concentrations were greatest in the cecum reflecting the high levels of Cu and Zn in the diet. Serum ceruloplasmin (an oxidase containing Cu) activity was related to liver copper in captive reindeer and caribou (P < 0.05, r2 = 0.82) during spring and winter but not during the rut. Michaelis-Menten kinetics of ceruloplasmin were measured in sera from captive reindeer, muskox (Ovibos moschatus) and moose (Alces alces) (n = 3/species). Maximum velocities (VMAX) were 42, 20 and 9 (IU x L(-1)); kM were 0.38, 0.55 and 0.62 (mM) for muskox, reindeer and moose respectively. Wild caribou (n = 3) from the Teshekpuk herd and moose (n = 3) from the Colville River had lower VMAX (7 IU x L(-1)) and higher km (1.9 mM) than their captive conspecifics. These kinetic parameters probably reflect differences in ceruloplasmin structure between species as well as differences in tissue reserves between populations within each species. Serum ceruloplasmin activity and kinetics can provide a non-lethal alternative to direct measures of hepatic Cu reserves in wild and captive populations. However, the method requires validation for the effects of sex, season, development and disease in each species.

Success and failure of reindeer herding in Greenland

Animal husbandry is a recent innovation in Greenland, specifically reindeer husbandry is less than 50 years old. Reindeer husbandry was first established in mid-west Greenland and later in southern Greenland. The Greenland hunter tradition and culture is, however, still dominant in many communities. During the 1980s and 1990s, the incompatibility of these two traditions resulted in the failure of reindeer husbandry in mid-west Greenland. There were neither herding nor seasonal herd movements. Animals remained year round on the winter range, which was destroyed as lichens were trampled every summer. Without seasonal herd movements both sustainable range use and control of the herd were lost. Today, there are just two semi-domestic reindeer herds left, and both are in southern Greenland. One herd is commercially successful, and the other is under development. In mid-west Greenland, semi-domestic reindeer husbandry officially ended in 1998, and a hunt was initiated to remove the remaining population. Possibly, by the year 2000 any animals left in this region will be considered wild caribou.

Timing and synchrony of activity in caribou

Activity data were analyzed to assess activity patterns of caribou (Rangifer tarandus granti). We hypothesized that equal day and night activity, termed nychthemeral activity, would be expected if food constitutes a limiting resource for a highly gregarious species. To test this hypothesis, we investigated activity patterns of two caribou populations at the same latitude: one captive with no food limitation and the other wild and free-ranging in the Alaska Range in interior Alaska known to be at the end of a 3-year low plane of nutrition. For captive caribou, activity patterns were determined from focal-animal behavioural observations each month except May. Data were collected on wild caribou using activity-recording radio collars in each of three seasons: late winter, postcalving, and midsummer. Wild and captive caribou exhibited nychthemeral activity and did not time activity to sunrise or sunset. Wild caribou exhibited no among-group synchrony. Within-group synchrony was high in both herds. Wild caribou exhibited significantly fewer cycles of activity than captive caribou. Longer resting bouts in late winter, and longer active bouts postcalving and in midsummer for wild caribou, were interpreted as behavioural responses to ecological effects of limited food availability, with and without snow, and disturbance by insects.

Estimating Lichen Biomass and Caribou Grazing on the Wintering Grounds of Northern Quebec: An Application of Fire History and Landsat Data

1. Landsat Thematic Mapper (TM) remote sensing imagery, previously published fire history data (Payette et al. 1989), and field observations were used to examine the influence of caribou grazing in part of their lichen-dominated wintering grounds in northern Quebec, Canada. Lichen biomass and percentage ground cover were measured in 1989 and 1992 over a large area (88 150km 2 ) stratified into five postfire successional stages. 2. Lichen-dominated vegetation covered 55%, moss- or shrub-dominated vegetation 25%, and water bodies 20% of the study area. Lichen biomass increased with postfire stand age, from 530 kg ha -1 in young stands ( 90 years). The cumulative amount of lichen cover removed by caribou before 1989 averaged 10% over the study area; by 1992 this value had risen to 21%. Between 1989 and 1992, ground cover of lichens decreased from 55 to 42%. Lichen removal was concentrated in stands > 50 years old, where it occurred at a rate of about 5% per year. No significant change in lichen cover was observed in younger stands. 3. The number of caribou grazing in the study area between 1989 and 1992 exceeded the carrying capacity estimated from the annual increment in lichen biomass ( 1% year -1 ); lichens were reduced by both consumption and collateral damage. Lichen cover can be progressively reduced by winter grazing of caribou in large lichen-dominated continental areas in much the same way as in insular ranges. 4. The combination of remote sensed and fire history data may be a helpful tool for managing large herds of wild caribou.