Sea Ice and Migration of the Dolphin and Union Caribou Herd in the Canadian Arctic: An Uncertain Future

Abstract

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...

Observation of Arctic island barren-ground caribou (Rangifer tarandus groenlandicus) migratory movement delay due to human induced sea-ice breaking

“…In the context of observed changes in sea-ice conditions and the increase in maritime shipping activity, the impact of sea-ice breaking is of great concern for the movements and viability of Arctic wildlife and particularly of caribou (Rangifer tarandus) populations using sea-ice to migrate from one island to the other (Miller et al, 1977;Miller & Gunn, 1978) or between an island and the mainland Poole et al, 2010). Connectivity between islands or between islands and the mainland is key to the viability of Arctic island caribou populations (Miller et al 2005;2007), and maritime tra c and sea-ice breaking has been a concern for local communities who rely on caribou and other wildlife for subsistence, cultural, and economic activities.…”

“…While caribou are good "swimmers", and water-crossings between islands have been documented (Miller, 1995), it is unlikely that it happens when the distance to cross is more than a few kilometres or when air temperature is well below freezing. Although the documentation of sea-ice crossings (Miller et al, 2005;Poole et al, 2010) and seasonal habitat and forage use (Hughes, 2006) provide some support for the assumptions of demographic e ects if the connectivity between the islands or between islands and the mainland is a ected (COSEWIC, 2004), there is limited information on veri ed and quantied impacts on caribou movements due to anthropogenic alteration of the sea-ice. Changes in sea-ice conditions and increased maritime tra c were part of the justi cation for the Dolphin and Union caribou (R. t. groen- Rangifer, Special Issue No.…”

“…33, 2013 (1): 115-122 Observation of Arctic island barren-ground caribou (Rangifer tarandus groenlandicus) migratory movement delay due to human induced sea-ice breaking landicus) herd to be currently listed as Special Concern under the Species at Risk Act (Canada Gazette, 2011). e Dolphin and Union herd is somewhat unique as its annual range encompasses Victoria Island for calving, postcalving, and rut, and the mainland as its main winter ground (Gunn & Nishi, 1998;Poole et al, 2010). is implies annual migrations (fall and spring) across the sea-ice between Victoria Island and the mainland.…”

“…is implies annual migrations (fall and spring) across the sea-ice between Victoria Island and the mainland. e fall migration across the sea-ice is preceded by a staging period (Poole et al, 2010) when caribou aggregate along the south coast of Victoria Island waiting for the ice to form between the Island and the mainland. As soon as the ice is strong enough, the crossing happens very rapidly with, in some areas, pauses on islands along the way (Poole et al, 2010).…”

“…e fall migration across the sea-ice is preceded by a staging period (Poole et al, 2010) when caribou aggregate along the south coast of Victoria Island waiting for the ice to form between the Island and the mainland. As soon as the ice is strong enough, the crossing happens very rapidly with, in some areas, pauses on islands along the way (Poole et al, 2010). We describe the short-term e ects on the Dolphin and Union caribou herd migratory movements due to the temporary maintenance of an open channel through the sea-ice in the fall 2007, at Cambridge Bay, Victoria Island, Nunavut.…”