Occurrence Maps

Rough-legged Hawk

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Rough-legged Hawk is a quintessential Arctic raptor, breeding across the tundra and wintering in open country almost nationwide. It is most common to the north in winter, with peak abundance on the western Great Plains and Great Basin Desert. East of the Mississippi its distribution is quite patchy and largely restricted to those few areas that provide truly extensive grasslands (including marshes).

Since so many STEM models show Neotropical birds coming north for the summer, it is almost refreshing to see the opposite pattern. Rough-legged Hawks do not occur anywhere in the Lower 48 during summer, and instead begin to arrive in mid-October. By 1 April, most have withdrawn back to the north. This timing is almost a perfect mirror image of Swainson’s Hawk, which arrives in March and April and withdraws in September and October. Both occupy some of the same prairies and while Swainson’s eats lots of insects during the summer months, both are rather small and slender raptors that may take advantage of some of the same rodent prey.

As with many grassland and high desert species, the distribution of this species at its peak reflects where some of the wide open spaces are. A few well-known concentration points show up prominently, including the Klamath Basin (south-central Oregon and northern California) and the Snake River Valley (Idaho). The relatively high occurrence metrics (but quite low compared to other species, peaking at 6%!) in those areas swamp out many of the other areas, including the central Great Plains where the species is in fact quite common as well. For most of us, seeing even one Rough-legged Hawk is a treat, so the high counts in eBird in Washington, and especially Idaho, help us put these occurrence patterns in context.