Terry McIntyre took this photo of a
white morph Gyrfalcon with a full crop. It almost landed on our ship
while we were sailing in Baffin Bay on 31 August 2017.
On this trip, we saw
five Gyrfalcons, the worldʼs largest falcon. Three were on land and
two were at sea where one Gyrfalcon carried prey in its talons and
the other had a full crop, having recently eaten. We discovered that
Gyrfalcons are as comfortable hunting at sea as they are on land.
During 2000-2004, researchers in Greenland tagged 48 Gyrfalcons with
satellite transmitters. They determined the breeding home range of
some female Gyrfalcons varied from 140 to 1197 square km and for two
males it was around 500 square km. Wintering ranges involved long
distances and time spent at sea. For example an adult male Gyrfalcon
travelled 3137 km over a 38-day period (83 km⁄day) from northern
Ellesmere Island, Nunavut, to its winter range in southern
Greenland, and an adult female travelled 4234 km from Thule in
northwest Greenland to southern Greenland via eastern Canada over an
83-day period (51 km⁄day). However some birds simply wandered
continuously during the non breeding season, presumably resting on
sea ice and icebergs and feeding on seabirds. This research
highlighted the huge size of the winter range of Gyrfalcons,
including at sea, and the importance of sea ice far from land.
Reference: Ibis, International Journal of Avian Science.
Seasonal Movements of Gyrfalcons falco rusticus include
extensive periods at sea. Authors Kurt K. Burnham and Ian Newton.