Research + Data

With multiple years of formal counting under our belts, the Mackinac Straits Raptor Watch continues to build a valuable data collection – and to set and then break its own records.

Did you know that MSRW and Mackinaw City still hold the nationwide records for Red-tailed Hawks (22,420 set in 2019) and the most Golden Eagles seen east of the Mississippi (374 in 2015)?

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Red-tailed Hawks in 2019
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Golden Eagles in 2015

Our data collection value is extended via our membership in an international network of hawk count sites. Through collaboration with the Hawk Migration Association of North America, we gain expert help analyzing our data, and a nationwide context for understanding its significance.

Analysis conducted by Robert Pettit of HMANA, on all the Spring raptor migration data MSRW has collected to date, offers new insights about migrating raptors.

Our first seven years of count data reveals changes in the mix of raptors migrating through the Straits each Spring.

MSRW’s raptor research has proven useful in identifying changes over time at the Straits of Mackinac. What local trends mean in the broader context of raptor populations and their movements is not yet clear. Fluctuations in our counts may reflect changes in population size or may result from other factors such as year-to-year differences in wind and weather patterns, which are known to affect migration routes and timing. MSRW will continue our counts, and will examine our data together with the counts recorded at other hawk watches across the Great Lakes and Midwest region. Our aim is to build a better understanding of raptor migration patterns, and to use that understanding to inform policy, raptor habitat conservation, and raptor research priorities.

Mackinac Straits Raptor Watch has illustrated beyond a doubt that the Straits of Mackinac are a vital corridor for migrating raptors. That’s why we are committed to long-term annual monitoring here. We truly appreciate all who give to support this research. Won’t you join us?

Broad-winged Hawk and Red-shouldered Hawk numbers have increased dramatically. Also increasing, to a lesser extent, are numbers of Bald Eagles, Turkey Vultures, Red-tailed Hawks, and Peregrine Falcons.

Other species have decreased over this period, including Ospreys, American Kestrels, and Sharp-shinned Hawks.

The iconic Bald Eagle has made a strong comeback in Michigan and the Great Lakes. In the 1950s and 1960s, they had nearly vanished due to the use of DDT. Ospreys are now in decline, and ornithologists suspect that competition with the increasing number of Bald Eagles for nest sites near good fishing lakes may be a factor.

The decline of American Kestrels observed at the Mackinac Straits is consistent with their decline nationwide and appears to result from a mix of factors. Continued monitoring at the Straits of Mackinac and other hawk watch sites can alert scientists to species population declines before they reach catastrophic levels.

Click here to go to HMANA’s HawkCount raptor migration database, showing the most recent month’s data logged from the MSRW count site.

Click here to go to HMANA’s HawkCount raptor migration database, showing last year’s Spring hawk count data, logged from the MSRW Spring count site in Mackinaw City.

Click here to go to HMANA’s HawkCount raptor migration database, showing last year’s Fall hawk count data, logged from the MSRW Fall count site in St. Ignace.