Wolves (Canis lupus) and arctic foxes (Alopex lagopus) are the only canid species found throughout the mainland tundra and arctic islands of North America. Contrasting evolutionary histories, and the contemporary ecology of each species, have combined to produce their divergent population genetic characteristics. Arctic foxes are more variable than wolves, and both island and mainland fox populations possess similarly high microsatellite variation. These differences result from larger effective population sizes in arctic foxes, and the fact that, unlike wolves, foxes were not isolated in discrete refugia during the Pleistocene. Despite the large physical distances and distinct ecotypes represented, a single, panmictic population of arctic foxes was found which spans the Svalbard Archipelago and the North American range of the species. This pattern likely reflects both the absence of historical population bottlenecks and current, high levels of gene flow following frequent long-distance foraging movements. In contrast, genetic structure in wolves correlates strongly to transitions in habitat type, and is probably determined by natal habitat-biased dispersal. Nonrandom dispersal may be cued by relative levels of vegetation cover between tundra and forest habitats, but especially by wolf prey specialization on ungulate species of familiar type and behaviour (sedentary or migratory). Results presented here suggest that, through its influence on sea ice, vegetation, prey dynamics and distribution, continued arctic climate change may have effects as dramatic as those of the Pleistocene on the genetic structure of arctic canid species.

Climate warming is occurring at an unprecedented rate in the Arctic and is having profound effects on host-parasite interactions, including range expansion. Recently, two species of protostrongylid nematodes have emerged for the first time in muskoxen and caribou on Victoria Island in the western Canadian Arctic Archipelago. Umingmakstrongylus pallikuukensis, the muskox lungworm, was detected for the first time in 2008 in muskoxen at a community hunt on the southwest corner of the island and by 2012, it was found several hundred kilometers east in commercially harvested muskoxen near the town of Ikaluktutiak. In 2010, Varestrongylus sp., a recently discovered lungworm of caribou and muskoxen was found in muskoxen near Ikaluktutiak and has been found annually in this area since then. Whereas invasion of the island by U. pallikuukensis appears to have been mediated by stochastic movement of muskoxen from the mainland to the southwest corner of the island, Varestrongylus has likely been introduced at several times and locations by the seasonal migration of caribou between the island and the mainland. A newly permissive climate, now suitable for completion of the parasite life cycles in a single summer, likely facilitated the initial establishment and now drives range expansion for both parasites.

We evaluated the effects of several factors on the cortisol concentration of hair in wild brown bears. Our findings suggest the cortisol concentration may increase quickly following capture, even after hair growth has ceased. We emphasize the need for more validation of this measure as an indicator of long-term stress.

ABSTRACT. Caribou (Rangifer tarandus groenlandicus × pearyi) of the Dolphin and Union herd migrate across the sea ice between Victoria Island and the adjacent Canadian Arctic mainland twice each year, southward in fall-early winter and northward in late winter-spring. As a result of warmer temperatures, sea ice between Victoria Island and the mainland now forms 8 -10 days later than it did in 1982, raising questions about the impact of delayed ice formation on the ecology of the herd. We examined movements of female Dolphin and Union caribou as they relate to sea-ice crossings using four satellite collar datasets (46 caribou) obtained between 1987 and 2006. Since the late 1980s, Dolphin and Union caribou have been moving by early October to the southern coast of Victoria Island, where they stage until sea-ice formation allows migration across the sea ice to winter range on the mainland. Caribou spending the summer farther north on Victoria Island arrive later at the coast, which shortens their time spent on the staging area. During the study period, the collared caribou began crossings as soon as sea-ice formation allowed. Most caribou departed from just a few areas and tended to use the same departure areas each year. Highest mortality occurred during the fall-early winter ice crossing and in mid to late winter. Our research raises the question of how the Dolphin and Union caribou will persist in supporting harvesting if the crossing becomes riskier for them or if the seasonal migrations between Victoria Island and the mainland are interrupted.Key words: caribou, Rangifer, Dolphin and Union herd, migration, sea ice, climate, satellite collar, Canada, Nunavut RÉSUMÉ. Les caribous (Rangifer tarandus groenlandicus × pearyi) du troupeau Dolphin-et-Union migrent en passant sur la glace de mer entre l'île Victoria et la partie continentale adjacente de l'Arctique canadien deux fois par année, se dirigeant vers le sud à l'automne et au début de l'hiver, et vers le nord à la fin de l'hiver et au printemps. En raison des températures plus chaudes, la glace de mer entre l'île Victoria et la partie continentale se forme maintenant de huit à dix jours plus tard qu'en 1982, ce qui a pour effet de soulever des questions sur les incidences de la formation tardive de la glace sur l'écologie du troupeau. Nous avons examiné les mouvements des caribous femelles de Dolphin-et-Union pendant qu'elles traversaient la glace de mer à l'aide de quatre ensembles de données obtenus par colliers-satellites (46 caribous) entre 1987 et 2006. Depuis la fin des années 1980, les caribous de Dolphin-et-Union se déplacent vers le début d'octobre vers la côte sud de l'île Victoria, où ils transitent jusqu'à ce que la formation de la glace permette la migration pour passer l'hiver sur la partie continentale. Les caribous qui passent l'été plus au nord sur l'île Victoria arrivent à la côte plus tard, ce qui a pour effet de raccourcir le temps qu'ils passent en halte migratoire. Au cours de la période visée par l'étude, les caribous dotés d'un collie...

Muskoxen (Ovibos moschatus) are an integral component of Arctic biodiversity. Given low genetic diversity, their ability to respond to future and rapid Arctic change is unknown, although paleontological history demonstrates adaptability within limits. We discuss status and limitations of current monitoring, and summarize circumpolar status and recent variations, delineating all 55 endemic or translocated populations. Acknowledging uncertainties, global abundance is ca 170 000 muskoxen. Not all populations are thriving. Six populations are in decline, and as recently as the turn of the century, one of these was the largest population in the world, equaling ca 41% of today's total abundance. Climate, diseases, and anthropogenic changes are likely the principal drivers of muskox population change and result in multiple stressors that vary temporally and spatially. Impacts to muskoxen are precipitated by habitat loss/degradation, altered vegetation and species associations, pollution, and harvest. Which elements are relevant for a specific population will vary, as will their cumulative interactions. Our summaries highlight the importance of harmonizing existing data, intensifying long-term monitoring efforts including demographics and health assessments, standardizing and implementing monitoring protocols, and increasing stakeholder engagement/contributions.