Gould observed 'In the air their actions are playful, and their evolutions highly graceful and interesting, sometimes circling at immense height, at others chasing and dipping after each other...Those who have witnessed...the flight of a pair in pursuit of their prey over the mountain-side, or apparently playful tiltings with the Eagle, cannot but have admired their sweeping and graceful motions; at all events, mine are feelings of delight when watching them with never-tiring eyes.'

The illustration shows a male about two-thirds lifesize on a branch of Spruce Fir.

DISTRIBUTION: Breeding distribution is Holarctic and Neotropical, between 78°N and 15°N. Winters sporadically to lower elevations and to areas south of breeding range