One of several species and varieties of large Arctic falcons, esp. Falco rusticolus and the white species Falco Islandicus, both of which are circumpolar. The black and the gray are varieties of the former. See Illust. of Accipiter.

large and rare arctic falcon having white and dark color phases

The gyrfalcon (Falco rusticolus), also spelled gyr falcon (the 'g' is pronounced as "j" in "jar"), and also sometimes spelled gerfalcon, is the largest of all falcons. The gyrfalcon breeds on Arctic coasts and islands of North America, Europe and Asia. It is mainly resident, but some gyrfalcons disperse more widely after the breeding season, or in winter.

Gyrfalcon is a note / thought / task management system. Take your notes and other bits of information and: put the notes in hierarchical trees, tag, search, hyperlink, etc. Gyrfalcon is also designed with a clean interface that avoids modal interactions.