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Winter Raptor Surveys

Dark morph Rough-legged Hawks are not uncommon in the Sax-Zim Bog during the winter.

Started during the winter of 2015-2016, Winter Raptor Surveys have taken place in the Sax-Zim Bog Important Bird Area, as part of Hawk Migration Association of North America’s Winter Raptor Survey program. Surveys are undertaken once a month from November to late February/early March. The goal of the surveys are to document raptors on their wintering grounds. Species detected on the surveys vary greatly by region, with the most common winter raptors in the Sax-Zim Bog being Rough-legged Hawk, Bald Eagle, and honorary winter raptor Northern Shrike.

Our survey begins in Culver, MN and ends at the Lake Nichols boat landing. The route is outlined in yellow in the map above.

Our survey route stretches from the very southern border of the Sax-Zim Bog Important Bird Area and ends at the boat landing on Lake Nichols Road, covering a total of 93 miles.

To date, 34 surveys have been completed, documenting 194 birds of prey from 12 different species. Species documented include 4 owl species (Great Horned, Great Gray, Snowy, and Northern Hawk Owls), 2 eagle species (Bald and Golden Eagle), Northern Harrier, American Goshawk, 2 buteo species (Rough-legged and Red-tailed Hawk), Peregrine Falcon, and Northern Shrike. Of those species listed, Bald Eagle, Northern Shrike, and Rough-legged Hawk are the only regularly detected species.

In 2022, Head Naturalist Clinton wrote a summary of the project which was published in the Minnesota Ornithologists Union publication, The Loon. Read the summary below:

As result of these surveys, we have developed an understanding of how birds of prey utilize the Sax-Zim Bog during the winter season. One of the important bits of information gained from surveys has been the value of the region as stop-over habitat. Stop-over habitat refers to habitat utilized by birds during migration, as places to rest and refuel. Based on our detections of large numbers of birds during November and again in late-February/early-March, the farm fields and roadsides of the Sax-Zim Bog are crucial habitats for raptors to refuel on their way further south (or north!). Certainly, the habitat is also valuable for those birds of prey that overwinter in our area, but numbers of birds are detected at a much higher rate on the fringes of migration through our area.