Five birds to look for in January and February
By Brian Sullivan, Marshall Iliff, Chris Wood, and BirdWatching staff
Published: December 22, 2011
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Rough-legs shift winter range north
Rough-legged Hawks are wintering farther north than they did 30 years ago, and scientists say climate change and increasing numbers of Red-tailed Hawks are the likely causes.
Researchers Edward Pandolfino and Kimberly Suedkamp Wells analyzed Christmas Bird Count data from 1979 to 2006 and divided the data sets into two 14-year periods (1979-1992 and 1993-2006). The abundance of Rough-legs declined between the two periods on 91 percent of the count circles on the east and west coasts and across the southern half of the hawk’s winter range.
Numbers increased in only one region: the northern Great Plains from Montana and Wyoming east to Minnesota and Iowa, where 84 percent of count circles recorded more birds.
In winter, the hawk is found in open areas with little snow cover; it moves on after heavy snowfalls because deep snow hinders its hunting ability. It also competes for habitat and prey with the Red-tailed Hawk.
The increasing numbers of Rough-legs on the northern Great Plains coincided with decreased snow cover in the region, a symptom of the warming climate. Plus, the numbers of Red-tails on the coasts and in the southern half of the Rough-leg’s range went up, giving an advantage to the Red-tails.
Pandolfino and Suedkamp Wells reported their results in 2009 in the journal Western Birds.
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eBird is the real-time online checklist operated by the Cornell Lab of Ornithology and Audubon. Marshall Iliff, Brian Sullivan, and Chris Wood are eBird project leaders. Submit your bird sightings at ebird.org.
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