Top predators of the arctic tundra are facing a long period of very low prey availability during winter and subsidies from other ecosystems such as the marine environment may help to support their populations. Satellite tracking of snowy owls, a top predator of the tundra, revealed that most adult females breeding in the Canadian Arctic overwinter at high latitudes in the eastern Arctic and spend several weeks (up to 101 d) on the sea-ice between December and April. Analysis of high-resolution satellite images of sea-ice indicated that owls were primarily gathering around open water patches in the ice, which are commonly used by wintering seabirds, a potential prey. Such extensive use of sea-ice by a tundra predator considered a small mammal specialist was unexpected, and suggests that marine resources subsidize snowy owl populations in winter. As sea-ice regimes in winter are expected to change over the next decades due to climate warming, this may affect the wintering strategy of this top predator and ultimately the functioning of the tundra ecosystem.

The (breeding) owls were marked in July 2007 over a 115 km² area on the southern portion of Bylot Island, Nunavut, Canada (73°N, 80°W), using a bow-net trap.Note that for owl F7 the transmitter stopped during summer 2008. Data extracted in the frame of a joint ICSTI/PANGAEA IPY effort, see http://doi.pangaea.de/10.1594/PANGAEA.150150

Supplement to: Therrien, Jean-François; Gauthier, Gilles; Bêty, Joël (2011): An avian terrestrial predator of the Arctic relies on the marine ecosystem during winter. Journal of Avian Biology, 42(4), 363-369