Falco rusticolus

Gyrfalcon

Family: Falconidae · Class: Aves · Order: Falconiformes

The Gyrfalcon is the largest falcon species in the world, with females measuring 50 to 65 cm (20 to 26 inches) in length and weighing 1.1 to 2.1 kg (2.4 to 4.6 pounds). Males are smaller, typically 48 to 61 cm (19 to 24 inches) long and weighing 0.8 to 1.3 kg (1.8 to 2.9 pounds). The wingspan ranges from 110 to 160 cm (43 to 63 inches). Gyrfalcons exhibit considerable plumage variation, occurring in three main color morphs: white, gray, and dark. White morphs are predominantly white with dark barring, gray morphs display brownish-gray upperparts with streaked underparts, and dark morphs are heavily barred dark brown throughout. All morphs possess the characteristic falcon features of pointed wings, a hooked beak, and sharp talons. In California, Gyrfalcons are rare winter visitors and passage migrants, typically occurring from October through March. The species breeds in Arctic and subarctic regions across Alaska, northern Canada, Greenland, Iceland, and northern Eurasia. During winter, some individuals migrate south, with California representing the southern edge of their North American wintering range. Most California observations occur in the northeastern counties, particularly Modoc, Lassen, and Siskiyou counties, though scattered records exist throughout the Central Valley and coastal regions. Gyrfalcons inhabit open landscapes including tundra, coastal areas, grasslands, agricultural fields, and desert regions during winter. In California, they frequent large agricultural valleys, wetlands, and open rangeland where prey is abundant. The species shows preference for areas with scattered perches such as power poles, trees, or rock outcrops that provide hunting vantage points. They typically avoid heavily forested or densely urban environments. Gyrfalcons are powerful aerial hunters specializing in bird prey, particularly ptarmigan in their Arctic breeding range and various waterfowl, shorebirds, and upland game birds during winter. In California, they prey on ducks, geese, doves, and medium-sized songbirds. Hunting techniques include high-speed stoops from great heights and low, sustained chases across open terrain. The species is known for its exceptional flight speed, capable of reaching over 200 km/h (124 mph) in hunting dives. Gyrfalcons nest on cliff ledges or occasionally in abandoned raven nests, laying 2 to 5 eggs between April and June. Incubation lasts approximately 35 days, with young fledging after 46 to 53 days. The Gyrfalcon is not federally listed in the United States and maintains stable populations across most of its range. The International Union for Conservation of Nature classifies the species as Least Concern globally. In California, the species is not state-listed but is considered a sensitive species due to its rarity and limited occurrence. Climate change poses potential long-term threats through habitat shifts in Arctic breeding grounds and changes in prey distribution. The species faces localized threats from human disturbance, illegal falconry capture, and collisions with power lines and wind turbines.

Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, and more.