Gyrfalcons make icebergs home

Back in World War II there was a clever idea to use icebergs as floating aircraft carriers, but now we know birds of prey got there first.

A recent study that tracked the seasonal movements of 48 gyrfalcons with radio transmitters showed that some birds spent most of the winter over the ocean, probably using sea ice and icebergs as floating bases to hunt from.

A report of the research is published in the journal Ibis.

Kurt Burnham, who led the research whilst at Oxford University’s Edward Grey Institute and now runs the High Arctic Institute, told Matt Walker at BBC Nature:
‘I was very surprised by this finding… These birds are not moving between land masses, but actually using the ice floes or pack ice as winter habitat for extended periods of time.'

It’s almost unheard of for a land-based predatory bird to behave in this way, the only other example is the Snowy Owl, which is known to spend up to three months living on sea ice. An abundance of prey such as gulls, black guillemots, and sea ducks are believed to tempt the gyrfalcons into adopting this unusual lifestyle.

‘In the big picture this shows how adaptable and mobile gyrfalcons have to be in order to survive and reproduce in the harsh arctic environment they live in,’ Kurt comments.

The Edward Grey Institute is part of Oxford University's Department of Zoology.