Expanded abstract The role of seasonal migration in the near-total loss of caribou on south-central Canadian Arctic Islands

In 1980 the caribou (Rangifer tarandus) on Prince of Wales, Russell, and Somerset islands represented a healthy geographic population of an Arctic-island caribou ecotype on the southern tier of Canadian Arctic Islands. Those caribou exhibited complex patterns of seasonal range occupancy, involving annual seasonal migrations between and among the three islands and Boothia Peninsula (Miller et al., 1982, 2005; Miller, 1990). A large segment of the population migrated annually from the islands to Boothia Peninsula in early winter, wintered there, and then returned to the islands in the following late winter and spring. There is no evidence for large-scale emigration of caribou anywhere in the study area (Gunn et al., 2006). Caribou on Boothia Peninsula occur as two distinct ecotypes that are genetically different from the Arctic-island ecotype that occurred on Prince of Wales, Russell, and Somerset islands (e.g., Zittlau, 2004). Both the Boothia Peninsula ecotype and the Mainland ecotype calve mostly on northern Boothia Peninsula, northwest and northeast sections respectively (Gunn et al., 2000). After summering on the peninsula, most individuals of both ecotypes migrate south of the Boothia Isthmus onto adjacent mainland areas (Gunn et al., 2000). As a result, there were about the same number of caribou wintering on Boothia Peninsula when migrant caribou from Prince of Wales, Russell, and Somerset islands wintered there, as in summer when the migrant Arctic-island caribou had returned to Prince of Wales, Russell, and Somerset islands and the migrant Boothia Peninsula and Mainland caribou ecotypes had returned from their winter ranges farther south on the mainlan