Adult Caribou Research Articles

Artificial intelligence for automated detection of large mammals creates path to upscale drone surveys

Imagery from drones is becoming common in wildlife research and management, but processing data efficiently remains a challenge. We developed a methodology for training a convolutional neural network model on large-scale mosaic imagery to detect and count caribou (Rangifer tarandus), compare model performance with an experienced observer and a group of naïve observers, and discuss the use of aerial imagery and automated methods for large mammal surveys. Combining images taken at 75 m and 120 m above ground level, a faster region-based convolutional neural network (Faster-RCNN) model was trained in using annotated imagery with the labels: “adult caribou”, “calf caribou”, and “ghost caribou” (animals moving between images, producing blurring individuals during the photogrammetry processing). Accuracy, precision, and recall of the model were 80%, 90%, and 88%, respectively. Detections between the model and experienced observer were highly correlated (Pearson: 0.96–0.99, P value < 0.05). The model was generally more effective in detecting adults, calves, and ghosts than naïve observers at both altitudes. We also discuss the need to improve consistency of observers’ annotations if manual review will be used to train models accurately. Generalization of automated methods for large mammal detections will be necessary for large-scale studies with diverse platforms, airspace restrictions, and sensor capabilities.

A Burning Question: What are the Implications of Forest Fires for Woodland Caribou?

ABSTRACTCanada's federal recovery strategy for boreal woodland caribou (Rangifer tarandus caribou) classifies areas burned by forest fire as disturbed habitat. This assignment of fire as a disturbance has potential economic and social implications across Canada, and influences plans and actions to achieve caribou conservation and recovery. Previous researchers have reported caribou avoid burned habitat, but these studies did not typically consider unburned residual patches within fire perimeters. Additionally, the implications of burned habitat on individual caribou survival is unclear. We examined resource selection by boreal woodland caribou of burns, and unburned residual patches, using global positioning system (GPS) locations for 201 caribou across 6 caribou populations in Alberta, Canada. We also examined if burned habitat affected the survival of adult female caribou. Caribou avoided burns and unburned residual patches. Increased use of burned habitats, however, did not lower the survival of adult caribou. Collectively, these results provide evidence to support current assertions that burns, and the embedded unburned residual patches are not preferred caribou habitat and increase our understanding of the implications of forest fire for caribou vital rates. Our investigation offers important information about the role of forest fire in caribou ecology and enhances the identification of disturbed habitat under recovery strategy guidelines to effectively address caribou population declines. © 2021 The Wildlife Society.

Slowing down wolves to protect boreal caribou populations: a spatial simulation model of linear feature restoration

AbstractIn Canada, boreal caribou (Rangifer tarandus caribou) are declining in numbers, in part due to increased predation by wolves (Canis lupus). One management option to reduce wolf–caribou interactions and thus protect caribou is to remove man‐made linear features (LFs), structures such as roads, trails, and cut lines, which are used by wolves as traveling paths. Linear features increase wolf traveling speed and could additionally facilitate wolf entry into caribou habitat. Our goal was to quantify the expected effect of LF removal on caribou mortality and investigate whether this LF restoration could be a sufficient measure to stop caribou declines. We simulated the effects of LF restoration on caribou adult and calf survival in spatially explicit wolf–caribou encounter models. The models were parameterized using Global Positioning System (GPS) data, hidden Markov models (HMMs), and information from the published literature. Complete LF restoration decreased wolf traveling speed and thus reduced caribou mortality. The proportional reduction in adult caribou mortality ranged from 10 to 25% of its original value, and the proportional reduction in calf mortality ranged from 8 to 23%, depending on caribou density, number of wolf packs, kill probability given an encounter, and detection distance of wolves for caribou. Building on the model output, we used empirical caribou data to calculate the effects of reduced mortalities on the finite rate of annual population change, . Assuming that 25% or less of calf mortality was wolf‐related, stayed below one, that is, populations kept declining, even with complete LF restoration. With 50% of calf mortality due to wolves, caribou populations stopped declining () if adult and calf mortality were reduced by at least 19 to 24%. However, these values were not achieved in a majority of the parameter combinations in our study, not even with complete LF restoration. Given that LF restoration as a single measure is unlikely to stop boreal caribou populations from declining, we used a case example to illustrate how LF restoration could make a small contribution in a portfolio of short‐term and long‐term management options to reduce wolf predation on caribou.

Multi-pathogen serological survey of migratory caribou herds: A snapshot in time

Pathogens can impact host survival, fecundity, and population dynamics even when no obvious disease is observed. Few baseline data on pathogen prevalence and diversity of caribou are available, which hampers our ability to track changes over time and evaluate impacts on caribou health. Archived blood samples collected from ten migratory caribou herds in Canada and two in Greenland were used to test for exposure to pathogens that have the potential to effect population productivity, are zoonotic or are emerging. Relationships between seroprevalence and individual, population, and other health parameters were also examined. For adult caribou, the highest overall seroprevalence was for alphaherpesvirus (49%, n = 722), pestivirus (49%, n = 572) and Neospora caninum (27%, n = 452). Lower seroprevalence was found for parainfluenza virus type 3 (9%, n = 708), Brucella suis (2%, n = 758), and Toxoplasma gondii (2%, n = 706). No animal tested positive for antibodies against West Nile virus (n = 418) or bovine respiratory syncytial virus (n = 417). This extensive multi-pathogen survey of migratory caribou herds provides evidence that caribou are exposed to pathogens that may have impacts on herd health and revealed potential interactions between pathogens as well as geographical differences in pathogen exposure that could be linked to the bio-geographical history of caribou. Caribou are a keystone species and the socio-economic cornerstone of many indigenous cultures across the North. The results from this study highlight the urgent need for a better understanding of pathogen diversity and the impact of pathogens on caribou health.

Evaluating the efficacy of translocation: maintaining habitat key to long-term success for an imperiled population of an at-risk species

The conservation of species at-risk has involved a wide range of recovery methods including population augmentation. Yet, there has been little formal evaluation of the efficacy of this potentially high risk and expensive approach. In the late 1990s, 32 mountain caribou (Rangifer tarandus caribou) were translocated to the Telkwa caribou herd in an effort to recover this declining population. We used Andersen–Gill survival models to explore the influence of forestry, linear features, and recreation on the survival of translocated and native caribou in the Telkwa herd as well as two control herds that had relatively little habitat disturbance and no translocation. We used location data from radio/GPS collars to monitor the mortality of individual caribou from the three populations over a 21-year period (1991–2012). Results suggested that forest harvest more negatively affected the survival of Telkwa caribou when compared to neighbouring herds and that translocated caribou were not predisposed to higher mortality relative to native caribou. Although the translocation effort stabilised the decline of the Telkwa caribou for a 10-year period, this herd has now declined to 22 individuals. Our research suggests that well managed translocation programs can result in the short-term stabilization or increase of small and declining populations of species at-risk. To achieve long-term recovery objectives, however, conservation strategies must address the underlying causes of decline. For woodland caribou in the mountains of western Canada, this requires managing anthropogenic disturbance to minimize densities of primary prey and their predators that act in concert to decrease the survival of adult caribou.

Modeling multispecies predator–prey dynamics: predicting the outcomes of conservation actions for woodland caribou

AbstractWoodland caribou is a Threatened or Endangered subspecies across much of Canada. In many cases, these caribou are declining because of human‐mediated predation in the form of apparent competition. Provincial and federal agencies have employed a number of conservation actions to arrest the decline, but insufficient time and limited replication make it difficult to test the efficacy of those activities. We built a three‐species population model that served as a tool to integrate current knowledge, explore uncertainties, and assess activities focused on the recovery of caribou. We applied the model to interconnected populations of caribou, moose, and wolves at two locations in Canada (Chinchaga [British Columbia], Charlevoix [Québec]) and explored the efficacy of conservation actions unique to each population: predator control, restoration of linear features, reduction of habitat for moose, supplementation, maternal pens, and predator exclosures. Results confirmed that caribou at these two locations faced different recovery challenges, dictated by specific population dynamics and threats. Wolf predation, enhanced by seismic lines and resource roads, was responsible for the decline of the simulated Chinchaga population. The most cost‐effective recovery actions for that population were long‐term lethal wolf control (λ1–50 = 1.014, $25,665/caribou), a large‐scale predator exclosure (λ1–50 = 1.015, $170,767/caribou), and the aggressive restoration of linear features (λ1–50 = 1.002, $531,675/caribou). In contrast, simulations suggested that calf predation by black bears, a fixed source of mortality in the model, limited the growth of the Charlevoix population. Assuming high survival of adult caribou and poor recruitment of juveniles, a maternal pen was the most effective action for the recovery of those caribou (λ1–50 = 1.004, $148,473/caribou). Short‐term population supplementation provided only a temporary increase in abundance (λ1–50 = 0.994, $62,143/caribou). The model was limited by ecological and data uncertainties, but served as an effective platform for representing and testing our understanding of the complex interspecific interactions that underlie the recovery of woodland caribou.

Habitat selection and population trends of the Torngat Mountains caribou herd

ABSTRACTUnderstanding why species at risk select certain habitat and what components of their life history influence changes in numbers can help mitigate population declines. The Torngat Mountains caribou (Rangifer tarandus) herd in northern Quebec‐Labrador, Canada, is declining, and few studies have examined the potential causes of this decline. We fitted 9 Argos and 26 global positioning system (GPS)‐collars on 35 adult caribou (25 female, 10 male) between 2011 and 2016 to assess seasonal habitat selection at 2 spatial scales, current and future population trends, and interactions with the neighboring Rivière‐George migratory caribou herd. The caribou of the Torngat Mountains herd selected areas with abundant food resources in winter and where prevalence of insects was lower in summer. They did not avoid areas where predation risk was high during calving. Spatial overlap with the Rivière‐George herd range decreased from 1990 to 2015 and was correlated with the size of the Rivière‐George population, which declined drastically during this period. The decline of the Torngat Mountains population was principally attributed to the low survival of adult females (0.72 annual survival rate) owing to subsistence harvest (9/24) and predation (7/24). Demographic models revealed that the growth rate of the population (λ) could vary from 0.83 (current) to 0.94 following a decrease in harvest pressure. Using demographic scenarios, we showed that the Torngat Mountains herd could continue to decrease if no management actions were taken to increase adult female survival. © 2018 The Wildlife Society.

Diet of Grey Wolves (Canis lupus) During Calving in a Moose– Caribou System in Northern Ontario

Grey Wolves (Canis lupus) are a leading proximate cause of declining populations of Woodland Caribou (Rangifer tarandus), a threatened species. Although predation on adult caribou has been well documented, less is known about predation on neonatal calves. We used scat analysis to examine the diet of wolves in an area of Ontario overlapping the receding southern limit of caribou occurrence. Wolves consumed mostly Moose (Alces americanus; 82.7%), followed by American Beaver (Castor canadensis; 10.9%), caribou (3.1%), and Snowshoe Hare (Lepus americanus; 1.5%). This low use of caribou is consistent with other evidence suggesting that caribou are a minor dietary component of wolves in this system; however, because most caribou consumption consists of calves, the impact on this slowly reproducing species may still be significant.

Decision-support model to explore the feasibility of using translocation to restore a woodland caribou population in Pukaskwa National Park, Canada

The distribution and abundance of woodland caribou (Rangifer tarandus caribou) have declined dramatically in the past century. Without intervention the most southern population of caribou in eastern North America is expected to disappear within 20 years. Although translocations have reintroduced and reinforced some populations, approximately half of caribou translocation efforts fail. Translocations are resource intensive and risky, and multiple interrelated factors must be considered to assess their potential for success. Structured decision-making tools, such as Bayesian belief networks, provide objective methods to assess different wildlife management scenarios by identifying the key components and relationships in an ecosystem. They can also catalyze dialogue with stakeholders and provide a record of the complex thought processes used in reaching a decision. We developed a Bayesian belief network for a proposed translocation of woodland caribou into a national park on the northeastern coast of Lake Superior, Ontario, Canada. We tested scenarios with favourable (e.g., good physical condition of adult caribou) and unfavourable (e.g., high predator densities) conditions with low, medium, and high numbers of translocated caribou. Under the current conditions at Pukaskwa National Park, augmenting the caribou population is unlikely to recover the species unless wolf densities remain low (&lt;5.5/1000 km2) or if more than 300 animals could be translocated.

What Happened to the Beverly Caribou Herd after 1994?

The Beverly herd was one of the first large migratory herds of barren-ground caribou (Rangifer tarandus groenlandicus) defined in northern Canada on the basis of annual return of breeding females to traditional calving grounds near Beverly Lake in Nunavut. In 1994, herd size was estimated at 276 000 ± 106 600 (SE) adult caribou, but monitoring was minimal from 1994 to 2007. The next calving ground survey in 2002 revealed that caribou densities had dropped by more than half since 1994; annual surveys following from 2007 to 2009 demonstrated an extreme decline in numbers of calving cows, and by 2011, no newborn calves were seen there. We examine two possible explanations for the declining use of the traditional Beverly calving grounds from 1994 until their abandonment by 2011. One explanation is that a true numerical decline in herd size occurred, driven in at least the later stages by low cow survival and poor calf productivity, which led the remaining Beverly cows to switch to the neighbouring Ahiak calving ground 250 km to the north in 2007 – 09 and join that herd. An alternative explanation is that the decline on the traditional Beverly calving grounds was largely due to a distributional shift to the north of the Beverly herd that may have begun in the mid-1990s. We suggest that the former explanation is the more likely and that the Beverly herd no longer exists as a distinct herd. We acknowledge that gaps in monitoring of Beverly and Ahiak caribou hamper definitive evaluation of the Beverly herd’s fate. The large size sometimes achieved by barren-ground caribou herds is not a guarantee of persistence; monitoring shortfalls may hamper management actions to address declines.

Impacts of Human Disturbance on Large Prey Species: Do Behavioral Reactions Translate to Fitness Consequences?

Anthropogenic disturbances have been demonstrated to affect animal behavior, distribution, and abundance, but assessment of their impacts on fitness-related traits has received little attention. We hypothesized that human activities and infrastructure cause a decrease in the individual performance of preys because of anthropogenically enhanced predation risk. We evaluated the impacts of commercial logging and road networks on the fitness of a large herbivore known to be sensitive to human disturbance: the forest-dwelling woodland caribou (Rangifer tarandus caribou). For 8 consecutive years (2004–2011) we monitored 59 individuals using GPS telemetry in the Charlevoix region of Québec, Canada. We also used Very High Frequency telemetry locations collected on 28 individuals from 1999–2000. We related habitat selection of adult caribou at various spatio-temporal scales to their probability of dying from predation, and to indices of their reproductive success and energy expenditure. The probability that adult caribou died from predation increased with the proportion of recent disturbances (including cutblocks ≤5 years old) in their annual home range. The respective effects of increasing paved and forestry road densities depended upon the overall road density within the home range of caribou. At a finer scale of 10 to 15 days before their death, caribou that were killed by a predator selected for recent disturbances more than individuals that survived, and avoided old mature conifer stands. The home range area of caribou increased with road density. Finally, the composition of the home range of females had no effect on their reproductive success. We show that human activities and infrastructure may influence the individual performance of large prey species in highly managed regions. We outline the need to consider the full set of impacts that human development may have on threatened animal populations, with particular emphasis on predator-prey relationships and population dynamics.

Peary caribou (Rangifer tarandus pearyi) and muskoxen (Ovibos moschatus) on northwest Victoria Island, Northwest Territories

An aerial population survey of Peary caribou (Rangifer tarandus pearyi) and muskoxen (Ovibus moschatus) on Victoria Island, Northwest Territories, was conducted in July 2010. The population estimate of adult Peary caribou was 150 ± 104 (95% Confidence Interval [CI]) was not significantly different than the 2005 estimate of 66 ± 61 (P &lt; 0.05). There was also an estimate of 430 ± 214 (95% CI) adult Dolphin-Union caribou (R. t. groenlandicus x pearyi) in the study area. However, these caribou represent only a small portion of the Dolphin-Union herd. The population estimate of 11 442 ± 1637 (95% CI) adult muskoxen is not significantly different than the 2005 estimate of 12 062 ± 2156 (P &lt; 0.05).

Population survey of Peary caribou (Rangifer tarandus pearyi) and muskoxen (Ovibos moschatus) on Banks Island, Northwest Territories, July 2010

We conducted a systematic aerial transect survey of Peary caribou (Rangifer tarandus pearyi) and muskoxen (Ovibus moschatus) on Banks Island, Northwest Territories, in July 2010. The population estimate of adult Peary caribou was 1097 ± 343 (95% Confidence Interval: CI), which is not significantly different from the 2005 estimate of 929 ± 289 (95% CI; P &lt; 0.05). The current number, however, is a 4- to 9-fold decrease since the 1980s. The adult muskoxen population estimate was 36 676 ± 4031 (95% CI), which is significantly lower than the 2005 estimate of 47 209 ± 3997 (95% CI; P &lt; 0.05).

Glucocorticosteroid concentrations in feces and hair of captive caribou and reindeer following adrenocorticotropic hormone challenge

Climate change and industrial development are contributing to synchronous declines in Rangifer populations across the Arctic. Chronic stress has been implicated as a proximate factor associated with decline in free-ranging populations, but its role in Rangifer is unspecified. Analysis of glucocorticosteroid (GC) concentration in feces, and more recently in hair, is a non-invasive method for monitoring stress in wildlife. Adrenocorticotropic hormone (ACTH) released from the pituitary gland stimulates GC release from the adrenals and can be administered to reflect adrenal activation. In this study, we assessed concentrations of GC metabolites in feces and cortisol in hair of Alaskan caribou (Rangifer tarandus granti) and reindeer (R. t. tarandus) following ACTH treatment. We predicted that ACTH challenge would increase concentrations of fecal GCs, but not hair cortisol because steroid deposited into the hair shaft occurs over an extended period of time (months) and is likely insensitive to acute adrenal stimulation. Adult caribou (n=10; mean age, 6.5 years old) exhibited a peak increase in fecal GCs 8h following a 2IU/kg dose of ACTH compared to pre-injection concentrations. In contrast, sub-adult reindeer (n=10, 0.8 years old) elicited a diminished response to the same dose. Quadrupling the dose (8IU/kg) prolonged the fecal GC response in female reindeer, but male reindeer were unresponsive. Hair cortisol was unaffected by a single ACTH challenge. Further investigation is required to ascertain whether subspecific differences in adrenal sensitivity are attributed to age or sex differences, or historical selective pressures from semi-domestication and/or sedentary life cycle in reindeer.

Fragmentation, dispersal and metapopulation function in remnant populations of endangered mountain caribou

AbstractPopulations that are fragmented in space may persist because of metapopulation function that relies on dispersal among subpopulations. Assuming that a fragmented distribution means that the species operates as a metapopulation can lead to erroneous conclusions about population structure, unless the dispersal traits of the organism are understood. A wide‐ranging large mammal with an increasingly fragmented distribution is the mountain caribou, found in the interior rain forests of British Columbia, Canada. These caribou are an endangered ecotype of woodland caribou Rangifer tarandus caribou, and, based on movements of adult caribou, their population has been divided into 18 subpopulations. Their numbers have declined over at least the last 25 years, and it is unknown if their fragmented distribution operates as a metapopulation linked by juvenile dispersal or is simply a step towards extinction. From a database of radio‐locations collected over a 23‐year period (1984–2007) from 358 caribou, we used a spatial index to define summer/fall composite ranges (breeding ranges) across their distribution. The 18 previously recognized subpopulations were fragmented further into 41 summer/fall composite ranges. Young animals (&lt;1 year of age) were not observed to disperse among subpopulations (0/26 opportunities) or even among summer/fall composite ranges (0/7). Similar results were found for animals 2 and 3 years of age. Breeding dispersal by adult caribou occurred in 1.4% of the observed opportunities (8/587). These dispersal rates are insufficient to rescue the smaller and declining subpopulations. We conclude that the distribution of these mountain caribou is more fragmented than thought previously and is not functioning as a classic metapopulation due to a lack of dispersal; rather, it is better described as an extreme non‐equilibrium metapopulation. Mountain caribou and other wide‐ranging species fragmented into subpopulations by human actions may appear to be in a metapopulation but unless they have the innate ability to disperse among subpopulations, the distribution is more likely the geographic pattern of the extinction process.

NEOSPORA CANINUM AND TOXOPLASMA GONDII ANTIBODY PREVALENCE IN ALASKA WILDLIFE

Free-ranging caribou and moose populations in some regions of Alaska undergo periodic declines in numbers. Caribou and moose are managed by the state as valuable resources for not only sustenance and subsistence, but also for cultural heritage. Incidence and prevalence of diseases that may impact herd health and recruitment from year to year are relevant to management decisions aimed to protect the long-term viability of these herds. Neospora caninum and Toxoplasma gondii are two apicomplexan parasites that can cause neurologic disease and abortions in their intermediate hosts and less frequently cause disease in their definitive hosts. The definitive hosts of N. caninum and T. gondii are canids and felids, respectively, and prevalence in the environment is in part dependent on maintenance of the life cycle through the definitive hosts. Serum samples from caribou (Rangifer tarandus, n=453), wolf (Canis lupus, n=324), moose (Alces alces, n=201), black-tailed deer (Odocoileus hemionus, n=55), coyote (Canis latrans, n=12), and fox (Vulpes vulpes, n=9) collected in Alaska were assayed for N. caninum- and T. gondii-reactive antibodies with an immunofluorescent antibody test (IFAT) and a modified agglutination test (MAT), respectively. Seroprevalence of N. caninum was greater in caribou (11.5%) than in wolves (9.0%), moose (0.5%), or black-tailed deer (0%). Seroprevalence of T. gondii was greater in wolves (17.8%) than in caribou (0.4%), moose (0%), or black-tailed deer (0%). Seroprevalence of N. caninum and T. gondii were 16.7% and 0.0% in coyotes and 0.0% and 12.5% in fox, but small sample sizes prevented further analysis. Antibodies to N. caninum in young caribou compared to adult caribou suggest that vertical transmission may be an important component of new infections in Alaskan caribou. The spatial distribution of antibody-positive individuals across Alaska may reflect differences in frequency of definitive hosts and alteration of predation patterns among regions.

Effects of forest disturbance on density, space use, and mortality of woodland caribou

Woodland caribou (Rangifer tarandus caribou), a threatened species in Canada, inhabit landscapes dominated by mature and over-mature coniferous stands and tend to avoid areas used by other cervids, wolves (Canis lupus), and humans. We hypothesized that habitat modifications through logging and forest fire alter the space-use pattern of woodland caribou and result ultimately in lowered density. To test this hypothesis, density, distribution, space-use patterns, and mortality of caribou in disturbed landscapes (DLs) and undisturbed landscapes (ULs) of central Québec were quantified by a systematic aerial survey (42 539 km2) and telemetry of 68 adult caribou females. A ground survey of terrestrial and arboreal lichens was carried out to estimate production of lichens in DLs and ULs. Three populations that occupied between 10 000 and 15 000 km2 were identified in the study area. Caribou abundance was not limited by intraspecific competition for food. Production of terrestrial lichens was estimated to support 3 to 4 times the surveyed caribou density (1.2–2.1–100 km−2). Pregnancy rate was almost 100%, indicating that females were not food-limited. Space-use patterns were affected by forest disturbance. In DLs, caribou increased home range sizes and reduced fidelity to seasonal and annual home ranges, probably to avoid disturbed habitats. In response, the probability of surviving decreased with the extent of DL within home ranges. To help keep direct and indirect sources of caribou mortality at very low levels, forest management strategies should be oriented toward the protection of large interconnected blocks of forest to favour caribou spacing away from humans and predators and to maintain adequate space-use strategies.

Using ultrasound measurements of rump fat to assess nutritional condition of woodland caribou in northern British Columbia, Canada

Body reserves (fat and protein) of cervids are important to the reproductive success of individuals, and therefore may limit productivity of populations. We used a portable ultrasound machine to measure thickness of rump fat for 39 woodland caribou (Rangifer tarandus caribou) captured in the winters (January–February) of 2003 and 2004. We compared thickness of rump fat between pregnant and non-pregnant individuals in the Besa-Prophet drainage of northern British Columbia, Canada. Thirty-eight of the 39 females captured in British Columbia were adults and 34 of the adult caribou were pregnant (89.5 ± 5.1%, x– ± binomial SE). Pregnant individuals had more rump fat (0.60 ± 0.067 cm) than nonpregnant animals (0.20 ± 0.029 cm). Recognizing that deposition and mobilization of fat vary with age and possibly across the winter season, ultrasonography can be used as a non-invasive technique in the field to assist in estimating body fat of caribou.

Black Bear, &lt;em&gt;Ursus americanus&lt;/em&gt;, Ecology on the Northeast Coast of Labrador

Twenty-three Black Bears (Ursus americanus) were captured, 20 were measured, marked and/or radio collared, in northeastern Labrador, between 1996 and 1997. Bears used sea ice for travel, coastal islands for denning, hunted adult Caribou (Rangifer tarandus), and were the possible cause of Moose (Alces alces) calf mortality. Body sizes were small, median weight of adult females was 48 kg, and the sex ratio for captured subjects was 1:1. Four of six radio-collared females gave birth during the winter of 1997, female reproductive histories suggest delayed sexual maturity. Den entry occurred between October and December 1996; spring emergence occurred between April and May 1997, with estimated denning period ranging from 148-222 days. Visual observations of habitat use by radio collared subjects (n = 10) were not tested statistically but suggest that barren areas are used nearly as much as forest. Location data from three GPS collars deployed on three adult females were analysed using Chi-square goodness-of-fit test with Bonferroni correction; two females appeared to prefer forest habitats (p &lt; 0.05).

Population dynamics of the endangered mountain ecotype of woodland caribou (Rangifer tarandus caribou) in British Columbia, Canada

We used census results and radiotelemetry locations of &gt;380 collared individuals sampled over the entire distribution of the endangered mountain ecotype of woodland caribou (Rangifer tarandus caribou (Gmelin, 1788)) in British Columbia, Canada, to delineate population structure and document the size and trend of the identified populations. We also describe the spatial pattern of decline and the causes and timing of adult mortality and provide estimates of vital rates necessary to develop a population viability analysis. Our results indicate that the abundance of mountain caribou in British Columbia is declining. We found adult female annual survival rates below annual survival rates commonly reported for large ungulates. The major proximate cause of population decline appears to be predation on adult caribou. Spatial patterns of population dynamics revealed a continuous range contraction and an increasing fragmentation of mountain caribou into smaller, isolated subpopulations. The population fragmentation process predominantly occurs at the outer boundaries of the current distribution. Our results indicate that recovery strategies for mountain caribou should be directed at factors contributing to the fragmentation and isolation of mountain caribou populations as well as management strategies aimed at increasing adult survival.