Gyrfalcon

Gyrfalcon, Falco rusticolus  is a species of falcon in the Falconidae family. It is a very large, heavy-bodied, broad-necked falcon. It displays sexual dimorphism, the females being larger than the males  and they are the largest falcons. It comes in three colour morphs: white, grey and dark

Description
The gyrfalcon's tail is very broad and moderately long; wings fairly long and broad-based for a falcon; outer wing tapers to a blunt tip. It tail length equals that of its wing width.