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Abstract:The ability of many species to adapt to the shifting environmental conditions associated with climate change will be a key determinant of their persistence in the coming decades. This is a challenge already faced by species in the Arctic, where rapid environmental change is well underway. Caribou and reindeer (Rangifer tarandus) play a key role in Arctic ecosystems and provide irreplaceable socioeconomic value to many northern peoples. Recent decades have seen declines in many Rangifer populations, and there is strong concern that climate change is threatening the viability of this iconic Arctic species. We examine the literature to provide a thorough and full consideration of the many environmental factors that limit caribou and reindeer populations, and how these might be affected by a warming climate. Our review suggests that the response of Rangifer populations to climate change is, and will continue to be, varied in large part to their broad circumpolar distribution. While caribou and reindeer could have some resilience to climate change, current global trends in abundance undermine all but the most precautionary outlooks. Ultimately, the conservation of Rangifer populations will require careful management that considers the local and regional manifestations of climate change.Key words: climate change, caribou, reindeer, Rangifer, Arctic.Résumé : La capacité de bien des espèces à s'adapter aux conditions changeantes du milieu, associées au changement climatique, sera un facteur déterminant de leur pérennité dans les décennies à venir. Ceci constitue un défi auquel les espèces sont déjà confrontées dans l'Arctique, où la dégradation rapide de l'environnement est bien amorcée. Les caribous et les rennes (Rangifer tarandus) jouent un rôle essentiel dans les écosystèmes arctiques et apportent une valeur socio-économique irremplaçable aux populations du Nord. Au cours des dernières décennies, il y a eu des déclins dans beaucoup de populations de Rangifer et il règne une grande inquiétude que le changement climatique menace la viabilité de cette espèce iconique de l'Arctique. Nous examinons la littérature afin de fournir une étude complète et minutieuse des nombreux facteurs du milieu restreignant les populations de caribous et de rennes, et de déterminer comment ces populations pourraient être touchées par le réchauffement climatique. Notre examen suggère que la réponse des populations de Rangifer au changement climatique est, et continuera à être, diverse principalement en raison de leur vaste aire de répartition circumpolaire. Tandis que les caribous et les rennes pourraient avoir une certaine résilience au changement climatique, les tendances globales actuelles d'abondance des espèces affaiblissent toutes les perspectives sauf les plus préoccupantes. En fin de compte, la conservation des populations de Rangifer nécessitera une gestion prudente qui prenne en compte les manifestations locales et régionales de changement climatique. [Traduit par la Rédaction]

Assessing the impact of large carnivores on ungulate prey has been challenging in part because even basic components of predation are difficult to measure. For cougars (Puma concolor), limited field data are available concerning fundamental aspects of predation, such as kill rate, or the influence of season, cougar demography, or prey vulnerability on predation, leading to uncertainty over how best to predict or interpret cougar‐ungulate dynamics. Global Positioning System (GPS) telemetry used to locate predation events in the field is an efficient way to monitor large numbers of cougars over long periods in all seasons. We applied GPS telemetry techniques combined with occasional snow‐tracking to locate 1,509 predation events for 53 marked and an unknown number of unmarked cougars and amassed 9,543 days of continuous predation monitoring for a subset of 42 GPS‐collared cougars in west‐central Alberta, Canada. Cougars killed ungulates at rates near the upper end of the previously recorded range, and demography substantially influenced annual kill rate in terms of both number of ungulates (subad F [SAF] = 24, subad M [SAM] = 31, ad M = 35, ad F = 42, ad F with kittens <6 months = 47, ad F with kittens <6 months = 67) and kg of prey (SAF = 1,441, SAM = 2,051, ad M = 4,708, ad F = 2,423, ad F with kittens <6 months = 2,794, ad F with kittens >6 months = 4,280). Demography also influenced prey composition; adult females subsisted primarily on deer (Odocoileus spp.), whereas adult males killed more large ungulates (e.g., moose [Alces alces]), and subadults incorporated the highest proportion of nonungulate prey. Predation patterns varied by season and cougars killed ungulates 1.5 times more frequently in summer when juveniles dominated the diet. Higher kill rate in summer appeared to be driven primarily by greater vulnerability of juvenile prey and secondarily by reduced handling time for smaller prey. Moreover, in accordance with predictions of the reproductive vulnerability hypothesis, female ungulates made up a higher proportion of cougar diet in spring just prior to and during the birthing period, whereas the proportion of males increased dramatically in autumn during the rut, supporting the notion that prey vulnerability influences cougar predation. Our results have implications for the impact cougars have on ungulate populations and have application for using cougar harvest to manage ungulates.

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Natural disturbance patterns can provide useful information for ecosystem management. Our objective was to provide a detailed spatial picture of the pre-European settlement vegetation cover for the northwestern Wisconsin Pine Barrens and to compare it with the present vegetation cover. We analyzed the presettlement conditions using an extensive data set comprised of U.S. General Land Office surveyor records from the mid-19th century and related it to the vegetation cover in 1987 as depicted in a Landsat satellite forest classification. Changes were quantified by calculating differences in abundance and relative importance of tree species at presettlement time and today. Our results revealed a strong decline of jack, red, and white pine (Pinus banksiana Lamb., Pinus resinosa Ait., and Pinus strobus L., respectively), accompanied by an increase of oak (Quercus spp.), trembling aspen (Populus tremuloides Michx.), and other hardwood species. Certain vegetation types, e.g., red pine and oak savannas, were removed from the landscape. The forest density gradient of the presettlement landscape with open savannas and woodlands in the South and denser forests in the North disappeared. These changes, especially the increase in forest cover, are ecologically significant because numerous species are adapted to open habitat, which was previously created by fire, and their populations are declining.