Sea-ice crossings by caribou in the south-central Canadian Arctic Archipelago and their ecological importance

Abstract

The islands of the Canadian Arctic Archipelago lie immediately north of mainland North America in the Arctic Ocean. They are surrounded by ice for most of each year. Caribou (Rangifer tarandus) cross the sea ice in seasonal migrations among the islands and between the mainland and Arctic Islands. We compiled observations of 1272 discrete caribou crossings on the sea ice of northeastern Franklin Strait, Bellot Strait, Peel Sound and Baring Channel in the south-central Canadian Arctic Archipelago during four May—June search periods from 1977 to 1980. We clustered the 850 caribou trails found on the sea ice of northeastern Franklin Strait and on outer Peel Sound as 73 sea-ice crossing sites. We investigated whether caribou at the origin of a sea-ice crossing site could see land on the opposite side at the potential terminus. We measured the straight-line distance from where the caribou first came onto the ice (origin) to the first possible landfall (potential terminus). Potential termini were geodetically visible to caribou from elevated terrain near 96% of the origins of the 73 sea-ice crossing sites and still visible at sea-level at the origins on 68%. Caribou are able to take advantage of seasonal use of all of the islands and the peninsula by making sea-ice crossings, thereby helping to increase the magnitudes and durations of population highs and reduce their lows. Knowledge of these alternative pat¬terns of use made possible by sea-ice crossings is necessary to fully understand the population dynamics of these caribou and the importance of possible future changes in ice cover

An enigmatic group of arctic island caribou and the potential implications for conservation of biodiversity

“…erefore, for the purposes of conservation and management we consider those caribou to constitute one geographic caribou population ( Fig. 1: Miller et al, 2005;Gunn et al, 2006;Miller et al, 2007b). is population will hereafter be referred to as the Prince of Wales Island-Somerset Island-Boothia Peninsula Complex (PSBC) caribou population.…”

“…is population will hereafter be referred to as the Prince of Wales Island-Somerset Island-Boothia Peninsula Complex (PSBC) caribou population. Many of these caribou annually make a complex web of seasonal interisland or island-peninsula migrations within the PSBC, while some relatively few appear to remain year-round on a single island (Miller et al, 1982(Miller et al, , 2005. No consistent di erences in body size or other traits between the interisland migrants and the resident caribou have been detected.…”

“…No consistent di erences in body size or other traits between the interisland migrants and the resident caribou have been detected. Boothia Peninsula also contains a resident population of barren-ground caribou, but their range does not appear to overlap temporally with that of the migrant island caribou (F. Miller, unpublished data;Miller et al, 2005). We consider any caribou, other than barren-ground caribou, that occurs or was collected on Prince of Wales Island as a potential seasonal resident anywhere within the PSBC.…”

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

“…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.…”

“…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.…”