Gyrfalcon (Falco rusticolus)

Measurements: 0.48-0.60m long; wingspan 1.2-1.3m

Many birds of the far north have great charisma, and the Gyrfalcon, the largest and bulkiest of the falcons, is no exception. It is scarce, very shy, an inhabitant of extreme habitats, and often very distinctive to look at, especially the magnificent white morph from the High Arctic of Greenland. All this adds up to an exciting package.

By Ómar Runólfsson – Flickr: Gyr falcon – Falco rusticolus – Fálki, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=18526036

The Gyrfalcon feeds mainly on medium sized prey, especially birds. It usually catches them by flying low over the tundra or mountaintop and attempting to flush them into flight; if it is successful, it then lifts into the air to give itself momentum, and stoops down to strike from above. This policy is particularly successful in snaring grouse, and Ptarmigan and Willow Grouse can constitute a major part of the annual diet – after all, in winter there can be rather few other birds available at such high latitudes. A significant number of Gyrfalcon pairs also breed close to seabird colonies, especially those of auks, and gorge themselves upon the adults. When hunting they can take some birds straight from the water surface.

A minority of Gyrfalcons also feed on voles and lemmings and these, as well as grouse, show distinct cycles of abundance: boom and bust every 3-4 years for the rodents and the same every 10 years for grouse. This can make the production of young a complicated affair for the falcons, but if things look promising they will lay up to seven eggs, instead of the usual three or four. In good years, larger numbers than usual may move southward from their breeding areas in the winter, often turning up in numbers in Iceland and other parts of Northern Europe. 

From ‘Birds: A Complete Guide to All British and European Species’, by Dominic Couzens. Published by Collins and reproduced with permission.