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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

Many high-density populations of wild ungulates have exerted strong negative impacts on their habitat. A decrease in forage quantity and quality may affect individual growth, fecundity, and survival, especially under harsh winter conditions. On Anticosti Island, Que´bec, Canada, browsing by introduced white-tailed deer (Odocoileus virginianus) negatively affected boreal forest composition. Since the preferred contemporary winter forage of deer, balsam fir (Abies balsamea), has been almost completely extirpated from the island at browse height, deer are forced to increase the proportion of normally avoided forage, such as white spruce (Picea glauca), in their winter diet. We predicted that an increase in the proportion of white spruce in the diet would have detrimental effects on deer body condition and would affect their behavior and life history traits. We experimentally simulated a deterioration of winter forage quality in semi-natural enclosures by increasing the proportion of white spruce in the diet and examined the effects of winter diet quality on 1) forage intake, 2) body condition loss, 3) activity budget, and 4) survival of whitetailed deer fawns. Fawns fed the poor-quality diet maintained a higher forage intake rate throughout the winter than fawns fed the control diet, suggesting a compensatory response to the decrease of forage quality by consuming more forage during winter. Body mass decreased over the winter, but we did not observe any significant effects of diet quality on body mass loss. Diet quality did not influence the activity budget of fawns, but deer decreased activity in cold weather. The main determinant of overwinter survival was individual body mass in early winter. Our study suggests that deer have adapted to the extreme conditions encountered on Anticosti (i.e., harsh and long winters, low-quality browse, and a high-density population). Even though white spruce stands are gradually replacing balsam fir stands, our results suggest that de

Achieving a high social rank may be advantageous for individuals at high population densities, because dominance status may determine the priority of access to limited resources and reduce individual loss of body mass. The establishment of dominance relationships between individuals involves variable levels of aggressiveness that can be influenced by resource availability. The relationship between social rank and aggressiveness and the impacts of resource abundance on aggressiveness are, however, poorly understood, but may be relevant to understand the mechanisms determining dominance relationships between individuals. We experimentally simulated, in seminatural enclosures, a deterioration of winter forage quality induced by a high-density deer population and examined the effects of (1) social dominance and (2) diet quality on aggressiveness, forage intake and body mass loss of white-tailed deer, Odocoileus virginianus, fawns during two winters. Within diet-quality treatments, fawns were consistently organized into linear hierarchies and showed clear dominance relationships. Dominants initiated more interactions and showed higher aggressiveness than subordinates, but subordinates had higher forage intake than dominants throughout winter. Social rank did not influence cumulative body mass loss of fawns. During both winters, fawns fed the control diet maintained their aggressiveness level, whereas fawns fed the poor-quality diet decreased it. Our experimental approach revealed that white-tailed deer responded to a reduction in winter forage quality by modifying their aggressiveness, indicating that ungulates may show plasticity not only in their foraging behaviour in response to decreased resources but also in their social behaviour.

The social organization of many vertebrates is based on dominance behaviours occurring between pairs of individuals. Initial encounters between any two individuals can be crucial in determining the dominance relationship that will prevail between them throughout their lifetime. Achieving a high dominance status can be critical when competition for limited resources such as foraging sites is intense. The mechanisms that prevail for the establishment and stability of dominance relationships between individuals are, however, poorly understood. Our study aims to identify factors influencing the establishment of dominance relationships between young individuals, using white-tailed deer, Odocoileus virginianus, fawns as a model species, and to evaluate the possibility of long-term individual recognition after temporal separation. We used an experimental approach to test the alternative hypotheses that dominance relationships after temporal separation are explained by (1) the outcome of the previous encounters between opponents or (2) the body mass difference between individuals independently of the outcome of initial encounters. Social rank was established during the first encounters between individuals based on differences in body mass and was maintained afterwards even when the differences in mass between individuals were reversed. Our results suggest that individual long-term recognition may influence the outcome and the stability of dominance relationships after temporal separation of individuals. Dyadic dominance relationships seem to be established early in life and may then endure into adulthood.

Hormones play a central role in the physiology and behaviour of animals. The recent development of noninvasive techniques has increased information on physical and social states of individuals through hormone measurements. The relationships among hormones, life history traits and behaviours are, however, still poorly known. For the first time, we evaluated natural winter glucocorticoid and testosterone levels in young ungulates in relation to winter progression, diet quality and social rank. Overwinter, levels of glucocorticoid and testosterone decreased, possibly due to the decline of fawns’ body mass. The relationships between hormone levels and diet quality were surprising: Fawns fed the control diet presented higher glucocorticoid and lower testosterone levels then fawns fed the poor diet, suggesting that control fawns faced a higher nutritional stress than those on the poor diet. Similarly to other studies on social mammals, we found no relationship between faecal glucocorticoid levels and social rank, suggesting that social stress was similar for dominant and subordinate fawns during winter. Testosterone levels were not correlated to social rank as found previously in groups of individuals forming stable social hierarchies and maintaining stable dominance relationships. The simultaneous suppression of glucocorticoid and testosterone levels suggests for the first time that young ungulates present a hormonal strategy to prevent fast depletion of limited proteins and fat resources during winter.

Caribou (Rangifer tarandus) are a key species in Arctic ecosystems including northern Québec and Labrador. They play a central role in the ecology of predators and the structure of Arctic plant communities. In addition, caribou provide socioeconomic and cultural benefits from subsistence and sport hunting activities. Changes in the distribution and abundance of caribou due to global climate change would have serious biological, societal, and economic implications. Direct and indirect consequences of climate change on migratory caribou herds may include alteration in habitat use, migration patterns, foraging behaviour and demography. For example, caribou may experience a further northerly shift in distribution due to several factors including longer ice-free periods, increases in snowfall and extreme weather events, alterations in the fire regime, and changes in the distribution of insects and predators. Future research by Caribou Ungava, a research group interested in the ecology of migratory caribou in the context of climate change, will address the factors outlining variations in the population dynamics of caribou, implications for survival and reproduction, as well as the response of caribou habitat to different climate change scenarios. Management efforts focusing on mitigating greenhouse gases to reduce the potential effects of climate change, preserving high quality habitat, limiting anthropogenic landscape disturbances, and managing hunting in a sustainable manner, could alleviate stressors on migratory caribou of the QuébecLabrador peninsula., 0

Mycobacterium avium subspecies paratuberculosis (MAP) is a common pathogen in domestic ruminants that causes granulomatous inflammation of the small intestine leading to emaciation and wasting. Clinical disease (Johne’s disease) is also reported for several wild ruminant species. Between 2007 and 2009 we collected 561 fecal samples from caribou (Rangifer tarandus ssp.) representing 10 herds of migratory caribou, two herds of caribou from Greenland, and three populations of boreal woodland caribou. Feces were tested for MAP by bacterial culture and PCR targeting the IS900 insertion sequence. In total, 31 samples from eight different populations representing all three ecotypes were found positive for MAP by PCR, with one sample from the Rivière-aux-Feuilles herd also being culture positive for the type II (cattle) strain. The proportion of positive animals was particularly high in the Akia-Maniitsoq herd in Greenland, and Rivière-aux-Feuilles and Rivière-George herds in northeastern Canada (23.4, 11.5, and 10.0%, respectively). Our results indicate that MAP is present in several caribou herds of different ecotypes in northern Canada and Greenland and that MAP circulates within wildlife populations that do not have ongoing contact with domestic livestock. The epidemiology, pathogenicity, and effects on the health of caribou in northern ecosystems remain unknown.

Monitoring the body condition of ungulates is often considered an efficient way to assess habitat quality. It is therefore essential to select adequate measures to describe individual body condition. Because there is no consensus on which measurement(s) can best describe individual variability in body condition, field biologists often measure several variables, increasing processing time. From 2007 to 2009, we assessed body condition of female–calf pairs in 2 herds of migratory caribou in Northern Quebec/Labrador, Canada, using multiple measurements of size, mass, and fat depth. We sought to identify, using multivariate analysis, which measurement(s) had the greatest influence on a composite measure of body condition of females and calves at calving and weaning. Our results indicate that adult females are best described with a body bulkiness index opposing heavy and long/round-bodied females with high body protein reserves to light and short/slender-bodied females with low body protein reserves. At weaning, adult females can also be differentiated by a body fat index opposing fat to lean females. Calf body condition is best described by mass at birth and by a combination of mass and size measurements at weaning, opposing heavy and tall individuals with high protein reserves to light and short ones with low protein reserves. Overall, body mass appears to be the measurement that best describes individual variability in body condition of females and calves at calving and weaning. Our systematic comparison of body condition measurements will provide field biologists with guidance for future data collection., Le suivi de la condition corporelle chez les ongulés constitue un outil privilégié pour évaluer la qualité d’un habitat et son influence sur la survie et le potentiel reproductif. Il est ainsi essentiel d’identifier les mesures décrivant adéquatement la condition corporelle des individus. En général, les biologistes mesurent de nombreuses variables, sans toutefois qu’un consensus soit établi sur la ou les mesures décrivant le mieux la condition corporelle des individus. De 2007 à 2009, nous avons évalué la condition corporelle de paires de femelle-faon de deux troupeaux de caribous migrateurs du Nord du Québec/Ladrador, Canada, en récoltant diverses mesures individuelles de taille, de masse et de réserves corporelles. Notre objectif était d’identifier, à l’aide d’analyses multivariées, la ou les mesures ayant la plus grande influence sur une mesure composite de condition corporelle pour les femelles et les faons à la mise bas et au sevrage. Nos résultats indiquent que les femelles adultes sont départagées par un indice de corpulence opposant les femelles lourdes, longues et rondes avec des réserves protéiques élevées, aux femelles légères, courtes et minces avec de faibles réserves protéiques. Au sevrage, les femelles adultes sont aussi départagées par un indice de gras corporel opposant les femelles grasses aux femelles maigres. La condition corporelle des faons est décrite par la masse à la naissance et par une combinaison de mesures de masse et de taille corporelle au sevrage opposant les faons lourds et grands avec des réserves protéiques élevées, aux faons légers et courts avec de faibles réserves protéiques. Globalement, la masse corporelle explique la plus grande variabilité de la condition corporelle pour toutes les périodes et les classes d’âge. Notre comparaison ystématique de mesures de la condition corporelle guidera les biologistes dans leurs récoltes de données futures.

Besnoitia tarandi has been documented in free-ranging reindeer and caribou (Rangifer tarandus spp.) since 1922 throughout their arctic and subarctic ranges; however, very little is known about its epidemiology. We evaluated variables associated with B. tarandi prevalence and cyst density with the use of barren-ground caribou (Rangifer tarandus) from two migratory herds in northern Quebec: the Rivière-aux-Feuilles and the Rivière-George herds. Diagnosis of infection was made upon the microscopic observation of characteristic cysts in a formalin-fixed section of skin from the anterior aspect of the metatarsus. The density of cysts (number of B. tarandi cysts/mm2) was calculated in a section of the dermis extending from the epidermis of the skin to the base of the hair follicles and adnexal structures. Statistically significant associations between B. tarandi prevalence and cyst density, sex, age, and time of harvest were observed. Male caribou had a slightly higher prevalence compared to females, whereas cyst densities were similar between sexes. We found a nonlinear increase in the odds of infection by B. tarandi by age combined with the opposite trend for intensity of infection. Higher B. tarandi prevalence was observed in caribou sampled in the fall compared to June of the same year, suggesting that transmission is increased during the summer. Higher densities of cysts observed during the fall compared to June of the following year may be the result of the elimination of B. tarandi cysts from the dermis during the winter, or lower winter survival of heavily infected caribou. Comparisons of B. tarandi prevalence and density across herds should take into account these different variables.

The objective of this study was to establish a standardized protocol to monitor Besnoitia tarandi prevalence and intensity in barren-ground caribou (Rangifer tarandus) herds by: 1) calculating the relative sensitivity and specificity of the gross visual assessment of four anatomical sites compared with microscopic evaluation, and 2) determining which of four anatomical sampling sites was the most sensitive for detecting B. tarandi cysts by microscopy. Sampled tissues consisted of the conjunctiva of the left eye and skin sections from the rostrum, metatarsus, and thigh from 312 harvested caribou. Diagnosis of infection with B. tarandi was based on observation of at least one cyst by microscopic examination. For each tissue, the maximal density of cysts (number of B. tarandi cysts/mm(2) in the section examined) was calculated for a measured area consisting of the dermis extending from the epidermis of the skin to the base of the hair follicles and adnexal structures. For the conjunctiva, the entire submucosa was evaluated. Gross visual evaluation markedly underestimated B. tarandi prevalence in caribou with a relative sensitivity ranging from 0.29 in the conjunctiva to 0.13 in the skin section from the thigh, whereas relative specificities ranged from 0.98 to 1.00. The metatarsus and rostrum skin sections had the highest probabilities of cyst detection of all four anatomical sampling sites. The metatarsus harbored significantly higher densities of B. tarandi cysts than the rostrum, thigh, or conjunctiva. In conclusion, microscopic evaluation of a skin section from the anterior aspect of the mid-third portion of the metatarsal region could be used as a standardized comparative indicator of density of B. tarandi infection in Rangifer.

Industrial development, expansion of human populations and climate change increasingly affect habitats of migratory species. Effective protection of critical habitats is urgently required because several large migratory species have declined over the last decades. Protection of critical habitats, such as the calving grounds of migratory ungulates, may however require consideration of temporal shifts in spatial location. We assessed changes in the location of calving grounds used by migratory caribou over 35 years by the Rivière-George (RG) herd and 15 years by the Rivière-aux-Feuilles (RAF) herd, in Northern Québec and Labrador, Canada. We also evaluated the proportion of annual calving ground within protected Wildlife Habitats established to protect caribou calving grounds. The annual size and location of calving grounds changed substantially over time: calving ground size remained relatively stable for the RAF but it declined over 85% for the RG. Calving grounds moved 300 km northward in the Ungava peninsula for the RAF and shifted over 230 km back and forth to the Labrador coast for the RG. Despite recent modifications, legally designated Wildlife Habitats in Québec protected less than 20% of the RG and RAF calving grounds. Protection of calving grounds of migratory caribou must consider the dynamic use of space by adult females. We present recommendations on the use of available monitoring data to better protect calving grounds of migratory caribou and critical habitats of large migratory species.

Maternal characteristics can affect offspring traits, yet they are seldom included when considering density dependence of juvenile traits and population dynamics. We quantified the influence of population size and maternal traits on body condition of migratory caribou (Rangifer tarandus (L., 1758)) calves at birth and weaning. We contrasted female–calf pairs of the Rivière-George (RG) herd, which has recently declined to low population size, with pairs of the much larger Rivière-aux-Feuilles (RAF) herd. Calves of the RAF herd were lighter, smaller, and leaner than calves of the RG herd at both birth and weaning. Differences between herds, however, were much greater at weaning than at calving, suggesting a combined effect of herd size and summer range conditions on calf growth. Maternal mass was positively related to calf body condition during both periods. The positive influence of maternal mass on calf body condition was greater for RAF than RG calves at birth, but it was similar for the two herds at weaning. Our results show that the negative effect of population size on calf body condition can be modulated by maternal mass at calving, and that the positive effect of maternal mass is greater at weaning., Les caractéristiques maternelles peuvent influencer les traits de leur progéniture, mais sont rarement considérées lors de l’étude des effets de la densité sur les traits des juvéniles et la dynamique des populations. Nous avons évalué l’influence de la taille de population et des caractéristiques maternelles sur la condition physique des faons du caribou migrateur (Rangifer tarandus (L., 1758)) à la mise bas et au sevrage. Nous avons comparé des paires de femelle-faon du troupeau Rivière-George (RG) dont la taille de population a récemment décliné, à des paires du troupeau Rivière-aux-Feuilles (RAF) qui est présentement à taille de population élevée. Les faons du RAF présentaient une masse corporelle, une taille corporelle et un indice de gras des reins inférieurs aux faons du RG tant à la mise bas qu’au sevrage. Ces différences entre les troupeaux étaient plus importantes au sevrage qu’à la mise bas, suggérant un effet négatif combiné de la taille de population et des conditions d’alimentation estivale sur la croissance des faons. La masse maternelle était positivement corrélée à la masse des faons et ce, aux deux périodes. L’influence positive de la masse maternelle sur la masse du faon était plus forte pour le RAF que pour le RG à la naissance, mais semblable pour les deux troupeaux au sevrage. Nos résultats indiquent que l’effet négatif d’une taille de population élevée sur la condition corporelle des faons peut être modulé par la masse maternelle à la mise bas, et que cet effet positif de la masse maternelle est plus important au sevrage qu’à la mise bas.

Nitrogen (N) is a limiting nutrient for many herbivores, especially when plant availability and N content are low during the period of maternal investment, which is common for arctic ungulates. We used natural abundance of N isotopes to quantify allocation of maternal nitrogen to neonatal calves and milk in wild migratory caribou (Rangifer tarandus). We contrasted female-calf pairs from two herds in northern Quebec/Labrador, Canada: Rivière-George herd (RG; low population size with heavy calves) and the Rivière-aux-Feuilles herd (RAF; high population size and small calves). We assessed whether females of both herds relied on body protein or dietary N to produce the neonatal calf and milk at calving and weaning. Female caribou of both herds relied mostly on body N for fetal development. RAF females allocated less body N to calves than did RG females (92% vs. 95% of calf N), which was consistent with the production of calves that were 8% smaller in RAF than in RG. Allocation of body N to milk was also high for both herds, similar at calving for RAF and RG females (88% vs. 91% of milk N, respectively), but lower in RAF than RG females (95% vs. 99% of milk N) at weaning, which was consistent with a small but significantly greater reliance on dietary N supplies to support milk production at weaning. Female caribou used body protein stores to ensure a constant supply of N for fetal growth and milk production that minimized the effects of trophic mismatches on reproduction. The combination of migration and capital investment may therefore allow females to produce calves and attenuate the effects of both temporal and spatial mismatches between vegetation green-up and calf growth, which ultimately would reduce trophic feedbacks on population growth. Our data suggest that small changes in maternal allocation of proteins over the long period of gestation produce significant changes in calf mass as females respond to changes in resources that accompany changes in the size and d

Comparative studies across time and geographical regions are useful to improve our understanding of the health of wildlife populations. Our goal was to study parasitism in migratory caribou (Rangifer tarandus (L., 1758)) of North America and Greenland. A total of 1507 caribou were sampled across 12 herds to assess seven of their main helminth and arthropod macroparasites between 1978 and 2010. We sought to determine which factors such as sex, age class, herd size, and season best explained the prevalence and intensity of those parasites. Intensity of warble fly (Hypoderma tarandi (L., 1758)) larvae increased with age for males, whereas the opposite was observed in females. Prevalence of giant liver flukes (Fascioloides magna (Bassi, 1875) Ward, 1917), tapeworm Taenia hydatigena Pallas, 1766, and nose bot fly (Cephenemyia trompe (Modeer, 1786)) larvae was higher in adults than in calves. Prevalence of F. magna and T. hydatigena was higher at high herd size than at lower herd size. Greenland herds had the lowest prevalence of T. hydatigena and of the tapeworm Taenia krabbei Moniez, 1879, a higher intensity of H. tarandi, and a higher prevalence of C. trompe than the other herds. Of the herds from Quebec and Labrador, the Rivière-George herd had a higher prevalence of F. magna than the Rivière-aux-Feuilles herd. Our research provides the first comparative survey of these parasites of caribou across a broad spatial–temporal range., Les études comparatives réalisées avec un large éventail spatio-temporel sont fort utiles pour améliorer notre compréhension de l’état de santé des populations d’animaux sauvages. Nous avons étudié le parasitisme chez le caribou migrateur (Rangifer tarandus (L., 1758)) en Amérique du Nord et au Groenland. Un total de 1507 caribous ont été échantillonnés à travers douze troupeaux pour sept de leurs principaux helminthes et arthropodes macroparasites entre 1978 et 2010. Nous avons tenté de déterminer quels facteurs tels que le sexe, la classe d’âge, la taille du troupeau et la saison expliquaient le mieux la prévalence et l’intensité de ces parasites. L’intensité de Hypoderma tarandi (L., 1758) augmentait avec l’âge chez les mâles alors que le contraire a été observé chez les femelles. Les prévalences de Fascioloides magna (Bassi, 1875) Ward, 1917, Taenia hydatigena Pallas, 1766 et Cephenemyia trompe (Modeer, 1786) étaient plus élevées chez les adultes que chez les jeunes. Les prévalences de F. magna et de T. hydatigena étaient plus élevées à forte taille de troupeau qu’à faible taille de troupeau. Les troupeaux du Groenland avaient une plus grande intensité de H. tarandi et une plus grande prévalence de C. trompe que les autres troupeaux. Cette recherche fournit la première étude comparative de ces parasites à large échelle spatiale et géographique.

Comparative studies across time and geographical regions are useful to improve our understanding of the health of wildlife populations. Our goal was to study parasitism in migratory caribou (Rangifer tarandus (L., 1758)) of North America and Greenland. A total of 1507 caribou were sampled across 12 herds to assess seven of their main helminth and arthropod macroparasites between 1978 and 2010. We sought to determine which factors such as sex, age class, herd size, and season best explained the prevalence and intensity of those parasites. Intensity of warble fly (Hypoderma tarandi (L., 1758)) larvae increased with age for males, whereas the opposite was observed in females. Prevalence of giant liver flukes (Fascioloides magna (Bassi, 1875) Ward, 1917), tapeworm Taenia hydatigena Pallas, 1766, and nose bot fly (Cephenemyia trompe (Modeer, 1786)) larvae was higher in adults than in calves. Prevalence of F. magna and T. hydatigena was higher at high herd size than at lower herd size. Greenland herds had the lowest prevalence of T. hydatigena and of the tapeworm Taenia krabbei Moniez, 1879, a higher intensity of H. tarandi, and a higher prevalence of C. trompe than the other herds. Of the herds from Quebec and Labrador, the Rivière-George herd had a higher prevalence of F. magna than the Rivière-aux-Feuilles herd. Our research provides the first comparative survey of these parasites of caribou across a broad spatial–temporal range., Les études comparatives réalisées avec un large éventail spatio-temporel sont fort utiles pour améliorer notre compréhension de l’état de santé des populations d’animaux sauvages. Nous avons étudié le parasitisme chez le caribou migrateur (Rangifer tarandus (L., 1758)) en Amérique du Nord et au Groenland. Un total de 1507 caribous ont été échantillonnés a` travers douze troupeaux pour sept de leurs principaux helminthes et arthropodes macroparasites entre 1978 et 2010. Nous avons tenté de déterminer quels facteurs tels que le sexe, la classe d’âge, la taille du troupeau et la saison expliquaient le mieux la prévalence et l’intensité de ces parasites. L’intensité de Hypoderma tarandi (L., 1758) augmentait avec l’âge chez les mâles alors que le contraire a été observé chez les femelles. Les prévalences de Fascioloides magna (Bassi, 1875) Ward, 1917, Taenia hydatigena Pallas, 1766 et Cephenemyia trompe (Modeer, 1786) étaient plus élevées chez les adultes que chez les jeunes. Les prévalences de F. magna et de T. hydatigena étaient plus élevées a` forte taille de troupeau qu’a` faible taille de troupeau. Les troupeaux du Groenland avaient une plus grande intensité de H. tarandi et une plus grande prévalence de C. trompe que les autres troupeaux. Cette recherche fournit la première étude comparative de ces parasites a` large échelle spatiale et géographique.

Genetic diversity is a key parameter to delineate management units, but many organisms also display ecological characteristics that may reflect potential local adaptations. Here, we used ecological and genetic information to delineate management units for a complex system involving several ecotypes of caribou (Rangifer tarandus) from Québec and Labrador, eastern Canada. We genotyped 560 caribou at 16 microsatellite loci and used three Bayesian clustering methods to spatially delineate and characterize genetic structure across the landscape. The different approaches employed did not converge on the same solution, and differed in the number of inferred genetic clusters that best fit the dataset but also in the spatial distribution of genetic variation. We reconciled variability among the methods using a synthetic approach that considers the sum of the partitions obtained by each of them and retrieved six genetically distinct groups that differ in their spatial extent across the range of caribou in the study area. These genetic groups are not consistent with the presently defined ecological designations for this species. Combining both genetic and ecological criteria, we distinguished eight independent management units. Overall, the management units we propose should be the focus of conservation and management actions aimed to maximize genetic and ecological diversity and ensure the persistence of caribou populations inhabiting increasingly disturbed landscapes.

Monitoring the body condition of ungulates is often considered an efficient way to assess habitat quality. It is therefore essential to select adequate measures to describe individual body condition. Because there is no consensus on which measurement(s) can best describe individual variability in body condition, field biologists often measure several variables, increasing processing time. From 2007 to 2009, we assessed body condition of female–calf pairs in 2 herds of migratory caribou in Northern Quebec/Labrador, Canada, using multiple measurements of size, mass, and fat depth. We sought to identify, using multivariate analysis, which measurement(s) had the greatest influence on a composite measure of body condition of females and calves at calving and weaning. Our results indicate that adult females are best described with a body bulkiness index opposing heavy and long/round-bodied females with high body protein reserves to light and short/ slender-bodied females with low body protein reserves. At weaning, adult females can also be differentiated by a body fat index opposing fat to lean females. Calf body condition is best described by mass at birth and by a combination of mass and size measurements at weaning, opposing heavy and tall individuals with high protein reserves to light and short ones with low protein reserves. Overall, body mass appears to be the measurement that best describes individual variability in body condition of females and calves at calving and weaning. Our systematic comparison of body condition measurements will provide field biologists with guidance for future data collection., Le suivi de la condition corporelle chez les ongulés constitue un outil privilégié pour évaluer la qualité d’un habitat et son influence sur la survie et le potentiel reproductif. Il est ainsi essentiel d’identifier les mesures décrivant adéquatement la condition corporelle des individus. En général, les biologistes mesurent de nombreuses variables, sans toutefois qu’un consensus soit établi sur la ou les mesures décrivant le mieux la condition corporelle des individus. De 2007 à 2009, nous avons évalué la condition corporelle de paires de femelle-faon de deux troupeaux de caribous migrateurs du Nord du Québec/Ladrador, Canada, en récoltant diverses mesures individuelles de taille, de masse et de réserves corporelles. Notre objectif était d’identifier, à l’aide d’analyses multivariées, la ou les mesures ayant la plus grande influence sur une mesure composite de condition corporelle pour les femelles et les faons à la mise bas et au sevrage. Nos résultats indiquent que les femelles adultes sont départagées par un indice de corpulence opposant les femelles lourdes, longues et rondes avec des réserves protéiques élevées, aux femelles légères, courtes et minces avec de faibles réserves protéiques. Au sevrage, les femelles adultes sont aussi départagées par un indice de gras corporel opposant les femelles grasses aux femelles maigres. La condition corporelle des faons est décrite par la masse à la naissance et par une combinaison de mesures de masse et de taille corporelle au sevrage opposant les faons lourds et grands avec des réserves protéiques élevées, aux faons légers et courts avec de faibles réserves protéiques. Globalement, la masse corporelle explique la plus grande variabilité de la condition corporelle pour toutes les périodes et les classes d’âge. Notre comparaison systématique de mesures de la condition corporelle guidera les biologistes dans leurs récoltes de données futures.

Genetic diversity is a key parameter to delineate management units, but many organisms also display ecological characteristics that may reflect potential local adaptations. Here, we used ecological and genetic information to delineate management units for a complex system involving several ecotypes of caribou (Rangifer tarandus) from Que´bec and Labrador, eastern Canada. We genotyped 560 caribou at 16 microsatellite loci and used three Bayesian clustering methods to spatially delineate and characterize genetic structure across the landscape. The different approaches employed did not converge on the same solution, and differed in the number of inferred genetic clusters that best fit the dataset but also in the spatial distribution of genetic variation. We reconciled variability among the methods using a synthetic approach that considers the sum of the partitions obtained by each of them and retrieved six genetically distinct groups that differ in their spatial extent across the range of caribou in the study area. These genetic groups are not consistent with the presently defined ecological designations for this species. Combining both genetic and ecological criteria, we distinguished eight independent management units. Overall, the management units we propose should be the focus of conservation and management actions aimed to maximize genetic and ecological diversity and ensure the persistence of caribou populations inhabiting increasingly disturbed landscapes.