Caribou Herd Research Articles

Temperature Drives Summer Group Size Dynamics of Eastern Migratory Caribou in the Hudson Bay Lowlands of Manitoba

Aggregation behavior is pervasive across a broad range of animals and the outcome of this behaviour has both risks and rewards. Large aggregations of animals are a distinctive characteristic of Migratory Caribou (Rangifer tarandus Linnaeus, 1758), primarily in response to the environment factors such as predation, although caribou may also aggregate during high summer temperatures, likely in an effort to mitigate parasitic biting flies. To see if caribou in the Cape Churchill Caribou Herd of the Eastern Migratory caribou (Rangifer tarandus groenlandicus Borowski, 1780) Designatible Unit, also displayed aggregation behavior in relation to warmer summer temperatures, we collected trail camera photos with associated temperature readings during the summer period (May to September) from 2017 to 2020 in their summer range in Wapusk National Park, Manitoba, Canada. We found that summer caribou aggregation size was positively associated with ambient temperature, with aggregations increasing in size as temperature increased. The mechanism behind this behaviour should be investigated, as we predict more frequent and large caribou aggregations as summer temperatures continue to warm.

Morphological Traits Are Not Consistently Related to Population Size in Four Migratory Caribou Populations Across North America.

To develop effective management to maintain or restore populations of large herbivores, wildlife managers require sound empirical data on their variations in size and associated parameters. Many studies have highlighted links between morphological traits of individuals and population density; however, less attention has been devoted to whether or not morphological traits can reliably inform on population size in years when no population estimates are available. We evaluated the relationships between three morphological traits (hind foot length, body mass, and body fat) and population size interpolated over three decades, for four migratory caribou (Rangifer tarandus) herds in northern Canada and Alaska. Our sample included 8865 measurements of 4473 individuals. We used a Bayesian modeling approach to evaluate the relationships between morphology and population size across different sex and age classes, considering different temporal scales and, when possible, phases of population growth or decline. We found that morphological traits were not consistently linked to population size. Statistically significant relationships existed for some combinations of herd and age classes, but weak to absent relationships were more common. Our study suggests that morphological traits alone cannot replace data obtained from aerial surveys to approximate population size when population trends are unknown. We discuss the usefulness of morphological traits to explain population size, and recognize their role as complementary metrics to inform the management and conservation of large herbivores, but conclude that morphological data should not be used to predict population size without information on population trends.

Behavioral adaptation to seasonal resource scarcity by Caribou (Rangifer tarandus) and its role in partial migration

Abstract Animals living in seasonal environments have adopted a wide array of tactics used to deal with seasonal resource scarcity. Many species migrate between habitats to reach areas where food resources are more plentiful as an attempt to address energetic demands through foraging. We assessed the winter behavioral adaptations of Caribou (Rangifer tarandus), a large ungulate inhabiting Arctic and sub-Arctic regions known for seasonal resource scarcity. Movement rates of Caribou are the lowest of the year during winter, revealing 1 mechanism individuals use to reduce energy expenditures. However, migratory individuals moved nearly twice as much as nonmigratory individuals during winter, suggesting that migratory individuals rely more upon income (forage), whereas nonmigratory individuals rely more upon capital (bodily reserves). Lichens are the primary winter forage for large, migratory herds of Caribou, and migratory individuals experienced more than 2.5 times greater lichen cover than nonmigratory individuals. We documented that both groups slowed their movement in areas of greater lichen cover, suggesting increased foraging time in these areas. Movement rates were greater near villages, which may be suggestive of disturbance, but the effect was weak. Overall energy saved by reduced movement rates was modest. However, energy savings were 11% of daily body energy lost or 47% of the demands of early pregnancy, which potentially could affect individual condition and/or fetal growth if not offset by increases in forage intake.

Population genetics of caribou in the Alaska-Yukon border region: implications for designation of conservation units and small herd persistence

Better knowledge of genetic relationships between the Fortymile caribou herd and its neighbors is needed for conservation decision-making in Canada. Here, we contribute the first fine-scale analysis of genetic population structure in nine contiguous caribou herds at the geographic boundaries between Barren-ground and Northern Mountain caribou, and at the Alaska-Yukon border. Using pairwise differentiation metrics, STRUCTURE, and discriminant analysis of principal components (DAPC) to analyze 15 microsatellite loci in 379 caribou, we found complex patterns of genetic differentiation. The Fortymile was the only herd assigned to more than one genetic cluster, indicative of its history as a larger herd whose range expansions and gene flow to other herds were likely important to maintaining diversity across a functioning genetic metapopulation. Some small herds (Chisana, Klaza, and White Mountains) were genetically distinct, while others (Hart River, Clear Creek, Mentasta) exhibited little differentiation from herds they occasionally overlap, including herds assigned to different conservation units (DUs). This genetic connectivity does not result from demographic connectivity, as episodic contact during rut, rather than herd switching, is the likely mechanism. Unusually, one small herd (White Mountains) maintained genetic differentiation despite rut overlap with Fortymile. Our data reveal that some herds with different ecological and behavioral attributes are demographically independent but nonetheless genetically connected. Thus, we suggest that managing caribou for an appropriate level of genetic connectivity, while also supporting herd persistence, will be essential to conserve caribou genetic diversity in the region.

Quantifying forest disturbance regimes within caribou (Rangifer tarandus) range in British Columbia.

Habitat disturbance is a major driver of the decline of woodland caribou (Rangifer tarandus caribou) in Canada. Different disturbance agents and regimes negatively impact caribou populations to different degrees. It is therefore critical that land managers and scientists studying caribou have a detailed understanding of the disturbance regimes affecting caribou habitat. In this work we use recent advances in satellite-based disturbance detection to quantify polygonal forest disturbance regimes affecting caribou ecotypes and herds in British Columbia (BC) from 1985 to 2019. Additionally, we utilize this data to investigate harvesting rates since the implementation of the Species at Risk Act (SARA) and publication of recovery strategies for caribou in BC. Southern Mountain caribou herds are the most threatened yet experienced the highest rates of disturbance, with 22.75% of forested habitat within their ranges disturbed during the study period. Over the study period, we found that in total, 16.4% of forested area was disturbed across all caribou herd ranges. Our findings indicate that caribou in BC face high, and in many cases increasing, levels of habitat disturbance. Our results provide a detailed understanding of the polygonal disturbance regimes affecting caribou in BC at the herd scale, and highlight the need for effective implementation of policies aimed at preserving caribou habitat.

Supporting Inuit food sovereignty through collaborative research of an at-risk caribou herd

IntroductionClimate change is increasing vulnerability to food insecurity and biodiversity loss for many Indigenous Peoples globally. For Inuit, food sovereignty is one expression of Indigenous self-determination, and it includes the right of all Inuit to define their own conservation policies. Caribou conservation is particularly pertinent because of the central role caribou play in Inuit food systems. The “Dolphin and Union” (DU) caribou herd is a critical component of Inuit food systems in the Canadian Arctic and has declined by 89% in 2020 (3,815) from the peak measured by aerial survey in 1997 (34,558).MethodsOur first objective was to identify insights about this herd from and with Inuit Qaujimajatuqangit (knowledge). Using thematic analysis, we created a collective account on the DU caribou herd through a research partnership among Indigenous knowledge keepers, government, and academia. Our second objective was to put our findings into the broader literature on the DU caribou herd and connect isolated data on their abundance and distribution.ResultsWe found understanding Inuit knowledge of caribou meant situating harvesters’ knowledge within their family history, harvesting methods, conservation ethics, and in relation to other harvesters. Through this framework, we conceptualized Inuit-described metrics of caribou status, resulting in three sub-themes of caribou trends over time – their abundance, distribution, and health, − and ending with conservation concerns and potential actions. The synthesized data indicated that the overall population size increased since ~1990s and then decreased after ~2000s alongside a range contraction. Our results add value to co-management literature by (1) articulating Inuit-described metrics of a population decline that inform continued monitoring and incorporation of these metrics into management planning and (2) synthesizing data from various studies on the DU caribou herd abundance and distribution that assists management to make informed conservation decisions based on Inuit and Western knowledge.DiscussionResults from this research contribute to understanding the six dimensions of environmental health, i.e., availability, stability, accessibility, health and wellness, Inuit culture, and decision-making power and management relating to caribou. The results contribute information that is used by to support environmental health, i.e., knowledge systems, policy, and co-management relating to caribou. Thus, this collaborative research study supports the expression of Inuit food sovereignty through caribou conservation.

Evidence of migratory coupling between grey wolves and migratory caribou

Large‐scale animal migrations influence population and community dynamics along with ecosystem functioning. The migratory coupling concept posits that movement of migrant prey can lead to large‐scale movements of predators. In northern ecosystems, spatial patterns and behavioral responses of grey wolf to spatio‐temporal changes in its primary prey distribution, the migratory caribou, remain poorly documented. We used a long‐term GPS dataset (2011–2021) of 59 wolves and 431 migratory caribou from the declining Rivière‐aux‐Feuilles herd (QC, Canada) to investigate movement patterns and space use of wolves related to caribou seasonal distribution. Wolves home ranges overlapped with areas used by caribou year‐round, especially in May and winter. Wolves exhibited three annual tactics: sedentary (17%), long‐distance migration (> 700 km) between wintering areas and the tundra (36%), and a medium‐distance migration, stopping their northward movement near the treeline (47%). Migratory wolves started spring migration northward earlier than caribou, intercepting their prey on their way to calving grounds, but departed southward for fall migration later than caribou, tracking them on their way back to wintering areas. Wolves near or overlapping areas used by caribou exhibited lower monthly movement rates compared to wolves located further away. Overlap of home range among wolves was higher during migrations and winter but decreased in summer when wolves rear pups and caribou are dispersed on summer grounds. We provide evidence of migratory coupling between grey wolves and migratory caribou, with most wolves adjusting their space use patterns to match their primary prey distribution. Although predation pressure may affect the dynamics of declining caribou herds, the global decline of that prey may in turn impact predators on the long‐term, potentially enhancing intraspecific competition for new resources. Highlighting this migratory coupling is a key step to develop appropriate conservation and management measures for both guilds in the context of large‐scale migratory prey decline.

An integrative and multi-indicator approach for wildlife health applied to an endangered caribou herd

Assessing wildlife health in remote regions requires a multi-faceted approach, which commonly involves convenient samplings and the need of identifying and targeting relevant and informative indicators. We applied a novel wildlife health framework and critically assessed the value of different indicators for understanding the health status and trends of an endangered tundra caribou population. Samples and data from the Dolphin and Union caribou herd were obtained between 2015 and 2021, from community-based surveillance programs and from captured animals. We documented and categorized indicators into health determinants (infectious diseases and trace elements), processes (cortisol, pathology), and health outcomes (pregnancy and body condition). During a recent period of steep population decline, our results indicated a relatively good body condition and pregnancy rates, and decreasing levels of stress, along with a low adult cow survival. We detected multiple factors as potential contributors to the reduced survival, including Brucella suis biovar 4, Erysipelothrix rhusiopathiae and lower hair trace minerals. These results remark the need of targeted studies to improve detection and investigations on caribou mortalities. We also identified differences in health indicators between captured and hunter sampled caribou, highlighting the importance of accounting for sampling biases. This integrative approach that drew on multiple data sources has provided unprecedented knowledge on the health in this herd and highlights the value of documenting individual animal health to understand causes of wildlife declines.

Spatializing oil and gas subsidies in endangered caribou habitat: Identifying political‐economic drivers of defaunation

AbstractReforming environmentally harmful subsidies is an international priority under the UN Convention on Biological Diversity. Research that links industrial subsidies to negative ecological impacts, however, is limited. This paper contributes to the emerging agenda of global “subsidy accountability” research by linking oil and gas subsidies to the decline of endangered caribou herds in British Columbia, Canada. While existing research concretely attributes the decline of caribou herds to industrial activity, including oil and gas development, we suggest there is a need to identify the political‐economic structures which drive ongoing industrial development in caribou habitat, including public subsidies. We use government data to map oil and gas wells in critical caribou habitat and determine how many are run by operators receiving provincial fossil fuel “royalty credits”. Ultimately, we find that 1678, or 54%, of oil and gas wells located within critical caribou habitat are run by companies that have received benefits from one or both of BC's largest royalty credit programs. This paper points to the need for further analysis of subsidies as indirect drivers of biodiversity loss on a global scale, as well as increased emphasis on political‐economic drivers in conservation research. It also highlights the obstacles to implementing appropriate conservation solutions in political‐economic contexts dominated by resource extraction.

Life history matters: Differential effects of abomasal parasites on caribou fitness

Parasites can impact wildlife populations through their effects on host fitness and survival. The life history strategies of a parasite species can dictate the mechanisms and timing through which it influences the host. However, unravelling this species-specific effect is difficult as parasites generally occur as part of a broader community of co-infecting parasites. Here, we use a unique study system to explore how life histories of different abomasal nematode species may influence host fitness. We examined abomasal nematodes in two adjacent, but isolated, West Greenland caribou (Rangifer tarandus groenlandicus) populations. One herd of caribou were naturally infected with Ostertagia gruehneri, a common and dominant summer nematode of Rangifer sspp., and the other with Marshallagia marshalli (abundant; winter) and Teladorsagia boreoarcticus (less abundant; summer), allowing us to determine if these nematode species have differing effects on host fitness. Using a Partial Least Squares Path Modelling approach, we found that in the caribou infected with O. gruehneri, higher infection intensity was associated with lower body condition, and that animals with lower body condition were less likely to be pregnant. In caribou infected with M. marshalli and T. boreoarcticus, we found that only M. marshalli infection intensity was negatively related to body condition and pregnancy, but that caribou with a calf at heel were more likely to have higher infection intensities of both nematode species. The differing effects of abomasal nematode species on caribou health outcomes in these herds may be due to parasite species-specific seasonal patterns which influence both transmission dynamics and when the parasites have the greatest impact on host condition. These results highlight the importance of considering parasite life history when testing associations between parasitic infection and host fitness.

How Many Generations are Available for Study? Expectations and Applications of Historical Ecological Insight from Bones Lying on Modern Landscapes

Skeletal remains lying on landscape surfaces are useful for evaluating historical states of living populations, but across how much time can such resources inform management and conservation? Further, how do differences in environmental setting impact the breadth of the available timeseries? Using radiocarbon dated bones from across the globe, we evaluated the relationship between the maximum duration that bones persist on landscapes and the mean annual temperature of each locality. We found that bones can persist for several millennia in cold (high-latitude) settings and that there is a strong link (R2 > 0.9, p < 0.01) between local temperature and the logged duration of maximum bone persistence. This relationship provides an initial expectation for the duration across which skeletal remains from different settings can provide historical ecological context. Across the Holarctic, caribou (Rangifer tarandus) are the most abundant large mammal and arguably the most economically significant one for multiple human cultures, including serving as a key nutritional and cultural resource. For migratory caribou, movements between winter ranges and spring calving grounds are among the longest annual migrations of any terrestrial species and maintaining access to these areas is a top conservation priority. But how long have herds used particular calving grounds? Shed female antlers lying on the tundra provide insight into historical calving geography because they are shed within days of giving birth. Following antler surveys across the Coastal Plain calving grounds (Arctic National Wildlife Refuge, Alaska) of the Porcupine Caribou Herd (PCH), we radiocarbon dated three highly weathered female antlers. Antler ages ranged between ~1,600 and >3,000 calendar years ago. These antlers provide the first physical evidence of calving activity on the PCH calving grounds from previous millennia and substantiate the long ecological legacy of the Coastal Plain as a caribou calving ground.

Shed Female Antlers as a Mineral Resource for Caribou on Spring Calving Grounds

Caribou (Rangifer tarandus) is the only extant deer species in which females produce antlers, but what are the roles and biological benefits of this feature? Female antler shedding is roughly synchronous with calving and, within populations, occurs at approximately the same time and place every year. Interestingly, spring and summer forage on caribou ranges can be insufficient in key minerals (calcium and phosphorus) that support nursing, and strategies for offsetting these deficits are poorly understood. We test the hypothesis that female caribou antlers, rich in calcium and phosphorus, provide mineral supplements for nursing females. Using antler and bone materials collected from the Coastal Plain calving grounds of the Porcupine Caribou Herd (Arctic National Wildlife Refuge, Alaska), we assessed the consumption of bone-derived nutrients by ungulates (Rangifer), carnivorans (Ursus, Canis, Vulpes), and rodents (Urocitellus, Microtus). Taphonomic surveys yielded over 1,300 antlers and hundreds of skeletal bones. We visually inspected each element for modifications and compared observed features to those generated by candidate modifiers. We identified 20 modification classes within the collection and attributed 10 to caribou. We found caribou gnawing on ~90% of shed antlers, but <10% of skeletal material, indicating a clear focus on antler resources. Co-occurring mammals rarely targeted antlers, with rodents gnawing 30%). On the calving grounds, caribou monopolize antler nutrients, likely driven by nursing females. Antlers can form dense accumulations on caribou calving grounds (>1,000 antlers/km2) and persist for centuries or longer, potentially serving as an important mineral-rich attractor. The annual return to calving grounds, during which females consume available antler resources and contribute new ones, may function as an unrecognized feedback mechanism for maintaining calving ground fidelity.

Shed female caribou antlers extend records of calving activity on the Arctic National Wildlife Refuge by millennia

Caribou (Rangifer tarandus) have among the longest annual migrations of any terrestrial mammal as they move from winter ranges to spring calving grounds. Biomonitoring records indicate broad consistencies in calving geography across the last several decades, but how long have herds used particular calving grounds? Furthermore, how representative are modern patterns of calving geography to periods that pre-date recent climatic perturbations and increased anthropogenic stresses? While modern ecological datasets are not long enough to address these questions, bones from past generations of caribou lying on the tundra provide unique opportunities to study historical calving geography. This is possible because female caribou shed their antlers within days of giving birth, releasing a skeletal indicator of calving. Today, the Coastal Plain of the Arctic National Wildlife Refuge (Alaska) is a key calving ground for the Porcupine Caribou Herd (PCH). To test the duration across which caribou have used this area as a calving ground, we radiocarbon dated three highly weathered female antlers collected from tundra surfaces on the Coastal Plain. Calibrated radiocarbon dates indicate that these antlers were shed between ~1,600 and more than 3,000 calendar years ago. The antiquity of these shed antlers provides the first physical evidence of calving activity on the PCH calving grounds from previous millennia, substantiating the long ecological legacy of the Coastal Plain as a caribou calving ground. Comparisons to published lake core records also reveal that dates of two of the antlers correspond to periods with average summer temperatures that were warmer than has been typical during the last several decades of biomonitoring. This finding expands the range of climatic settings in which caribou are known to use the current PCH calving grounds and suggests that the Coastal Plain of the Arctic Refuge may remain an important caribou calving ground during at least portions of predicted future warming. Discarded skeletal materials provide opportunities to assess the historical states of living populations, including aspects of reproductive biology and migration. Particularly in high-latitude settings, these insights can extend across millennia and offer rare glimpses into the past that can inform current and future management policies.

Diet flexibility of wolves and black bears in the range of migratory caribou

AbstractThe diet of predators can be highly variable, which is exemplified by their ability to acclimate to a wide range of ecological conditions. Such flexibility in foraging may be a key aspect of their performance in unpredictable environments such as at the edge of the range of a species or where food availability varies greatly in time and space. Gaining information on the diets of predators under such conditions could foster our comprehension of their ecological flexibility and the potential role of predation on the population dynamics of prey. We determined the diet of wolves (Canis lupus) and black bears (Ursus americanus) in northern Québec and Labrador (Canada) within the range of two migratory caribou (Rangifer tarandus) herds: the high-abundance Rivière-aux-Feuilles herd (RFH) and low-abundance Rivière-George herd (RGH). Worldwide, decline in caribou populations has become a concern, stressing the need to better understand the factors involved in these declines, including predation. In northern Québec (RFH range), caribou was the primary year-round prey of wolves while moose (Alces alces) and muskoxen (Ovibos moschatus) were consumed in some sectors. The diet of wolves in northern Labrador (RGH range) varied seasonally, with caribou, moose, and fish as main prey during different periods throughout the year. Black bear diets varied seasonally and regionally. Among the foods we analyzed, caribou was the main source of animal protein for bears in northern Québec and northern Labrador, except during a high abundance of Ungava collared lemming (Dicrostonyx hudsonius). Only bears in northern Québec ate caribou during late summer/fall. Our results highlight the diet flexibility of wolves and black bears in northern food webs, and how their diets change in relation to the distribution and abundance of prey. Our results will help quantify the potential impact of these predators on prey populations in northern systems.

Variation of hair cortisol in two herds of migratory caribou (Rangifer tarandus): implications for health monitoring.

Migratory caribou (Rangifer tarandus sspp.) is an ecotype of conservation concern that is experiencing increased cumulative stressors associated with rapid climate change and development in Arctic Canada. Increasingly, hair cortisol concentrations (HCCs) are being used to monitor seasonal hypothalamic-pituitary-adrenal axis activity of ungulate populations; yet, the effect of key covariates for caribou (sex, season, sampling source, body location) are largely unknown. The objectives of this research were 4-fold: first, we assessed the impact of body location (neck, rump) sampling sites on HCC; second, we assessed key covariates (sex, sampling method, season) impacting HCCs of caribou; third, we investigated inter-population (Dolphin and Union (DU), Bluenose-East (BNE)) and inter-annual differences in HCC and fourth, we examined the association between HCCs and indices of biting insect activity on the summer range (oestrid index, mosquito index). We examined hair from 407 DU and BNE caribou sampled by harvesters or during capture-collaring operations from 2012 to 2020. Linear mixed-effect models were used to assess the effect of body location on HCC and generalized least squares regression (GLS) models were used to examine the impacts of key covariates, year and herd and indices of biting insect harassment. HCC varied significantly by body location, year, herd and source of samples (harvester vs capture). HCC was higher in samples taken from the neck and in the DU herd compared with the BNE, decreased linearly over time and was higher in captured versus hunted animals (P < 0.05). There was no difference in HCC between sexes, and indices of biting insect harassment in the previous year were not significantly associated with HCC. This study identifies essential covariates impacting the HCC of caribou that must be accounted for in sampling, monitoring and data interpretation.

Exploring auditory thresholds for Reindeer, Rangifer tarandus

Current and proposed human development throughout high northern latitudes must assess and try to mitigate impacts on caribou and reindeer ( Rangifer tarandus ) herds. Sound created by development can be far-reaching, and determining the potential impacts of noise on wildlife can inform landscape use. To advance our understanding of Rangifer ’s potential response to anthropogenic noise, we must first understand what they can hear. Using domestic reindeer from the Large Animal Research Station at the University of Alaska Fairbanks, we performed a Brainstem Auditory Evoked Response to estimate auditory thresholds of the species. We assessed the central auditory response and tested the sensitivity in 6 female reindeer of various ages. Prior to our work, the lowest audible frequency for the species was reported to be 63 Hz in previous studies. We identified an auditory threshold lower limit of 30 Hz in our study subjects and quantified reindeer sensitivity thresholds (dB peSPL) to frequencies ranging from 30 to 16,000 Hz. Our results indicate that anthropogenic sounds previously thought to be beyond the hearing range of Rangifer —such as seismic exploration—are likely to be audible to the species, and therefore have the potential to affect their soundscape. We compared our findings on Rangifer hearing with new measurements of anthropogenic sounds recorded on passive acoustic monitors distributed throughout northern Alaska, as well as biological sounds produced by the Rangifer themselves (e.g., vocalizations and sesamoid clicks produced by the ankles). All classes of anthropogenic sound fall within the threshold range that we identified for Rangifer . Our findings have important implications for the assessment of environmental impacts within Rangifer range and will inform future soundscape ecology research.

A Caribou Decline Foreshadowed by Inuit in the Central Canadian Arctic: A Retrospective Analysis

The Dolphin and Union (DU) caribou herd (Rangifer tarandus groenlandicus x pearyi), locally referred to as Island caribou, is a unique and at-risk ecotype of caribou that ranges on Victoria Island and the adjacent mainland in the central Canadian Arctic. To facilitate the incorporation of traditional knowledge (TK) and better inform the required species recovery plan, we analyzed an archived set of TK interviews done in Ekaluktutiak and Kugluktuk, Nunavut, in 2003. The overarching theme throughout the interviews was that the DU caribou were dynamic, constantly adapting to the changing environment around them. Accounts provided previously unexplored connections between temporal and spatial trends in DU caribou distribution, population, ecology, and disease syndromes. Findings of fewer animals, range shift, and increased observations of disease in the late 1990s and early 2000s suggest that early signs of the declines that have resulted in the herd being reassessed as endangered today were already apparent to Kugluktukmiut in 2003. In contrast, Ekaluktutiakmiut were seeing a stable population. Shifts in caribou range and consequently harvesting ranges were described by both communities, but more evident in Kugluktuk. When combined, the differing accounts of the two communities provided a deeper understanding of caribou ecology and trends across seasons, years, and a broad spatial range. Community differences demonstrate the cruciality of considering unique place-based perspectives and the importance of mobilizing TK from communities and knowledge keepers throughout the caribou range for a herd-level understanding. This study highlights the importance of timely analyses and reporting on TK studies to ensure a nimble conservation response in a rapidly changing environment.

“It’s like a connection between all of us”: Inuit social connections and caribou declines in Labrador, Canada

Many caribou populations are declining across the Circumpolar North, presenting challenges for many Indigenous Peoples who have deep and enduring relationships with this animal. In Labrador, Canada, caribou herds have recently experienced population declines, including the George River herd, which has dropped by 99% from its peak, leading to the enactment of a total hunting ban in 2013 issued by the Government of Newfoundland and Labrador. The decline and subsequent hunting ban have affected various aspects of Inuit well-being. Using Inuit-led multi-media methods, this project heard voices of Inuit across the Nunatsiavut and NunatuKavut regions in Labrador, Canada, which (1) described the importance of caribou for Inuit social connections, (2) explored the ways in which the changes in caribou populations and management strategies are influencing these social connections, and (3) discussed the meaning and value of these social connections for Inuit well-being and the sustainability of Inuit-caribou relationships into the future. Data from video interviews (Nunatsiavut region: n = 54; NunatuKavut region: n = 30) were collected and analyzed using video and photography-based methods. Results characterized how caribou are important social connectors: human-caribou relationships are core to Inuit socialization, inter-connection, and shared experience and memory regarding families, communities, and food and knowledge sharing across Labrador’s landscape. Thus, declines in caribou populations and associated social interaction have had serious implications for Inuit identity, livelihoods, emotional well-being, cultural continuity, and knowledge transfer. In order to support the broader social-ecological system and the well-being of those who are connected to caribou, increased understanding and integration of these social connections into caribou-related decision making and research is recommended.

Critical summer foraging tradeoffs in a subarctic ungulate.

Summer diets are crucial for large herbivores in the subarctic and are affected by weather, harassment from insects and a variety of environmental changes linked to climate. Yet, understanding foraging behavior and diet of large herbivores is challenging in the subarctic because of their remote ranges. We used GPS video‐camera collars to observe behaviors and summer diets of the migratory Fortymile Caribou Herd (Rangifer tarandus granti) across Alaska, USA and the Yukon, Canada. First, we characterized caribou behavior. Second, we tested if videos could be used to quantify changes in the probability of eating events. Third, we estimated summer diets at the finest taxonomic resolution possible through videos. Finally, we compared summer diet estimates from video collars to microhistological analysis of fecal pellets. We classified 18,134 videos from 30 female caribou over two summers (2018 and 2019). Caribou behaviors included eating (mean = 43.5%), ruminating (25.6%), travelling (14.0%), stationary awake (11.3%) and napping (5.1%). Eating was restricted by insect harassment. We classified forage(s) consumed in 5,549 videos where diet composition (monthly) highlighted a strong tradeoff between lichens and shrubs; shrubs dominated diets in June and July when lichen use declined. We identified 63 species, 70 genus and 33 family groups of summer forages from videos. After adjusting for digestibility, monthly estimates of diet composition were strongly correlated at the scale of the forage functional type (i.e., forage groups composed of forbs, graminoids, mosses, shrubs and lichens; r = 0.79, p < .01). Using video collars, we identified (1) a pronounced tradeoff in summer foraging between lichens and shrubs and (2) the costs of insect harassment on eating. Understanding caribou foraging ecology is needed to plan for their long‐term conservation across the circumpolar north, and video collars can provide a powerful approach across remote regions.

Variation in winter site fidelity within and among individuals influences movement behavior in a partially migratory ungulate.

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.