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Kestrel Box Monitoring

The American kestrel is the smallest North American falcon, about the size and shape of a mourning dove, and is the most colorful of raptors. But don’t let their size fool you, as their small body is packed with a lot of intensity, their nickname is prairie lightning. They primarily feed on insects and other small prey such as small rodents. As you drive down highways and country roads, if you see a single bird on the power line, it is probably a kestrel searching for their next meal. You will also see them hovering over a field facing into the wind, flapping and adjusting their wings to stay in place.

The kestrel is experiencing a population decline in North America. In Wisconsin, we are seeing a 6.3% annual decline. The cause of the decline is unknown due to the lack of data. This underscores the need and importance for monitoring. Kestrels are a cavity nesting bird, so the lack of habitat is one probable cause, competition from the common starling for nesting spots is another and the use of pesticides in agricultural areas, and potential exposure to the West Nile virus add to the list of harzards for kestrels.

Presented below are the nesting results for my kestrel boxes. It should be noted that kestrels are quite territorial and the boxes need to be ½ mile apart, and, if the nesting attempt fails, they do not try again. I use a “camera on a stick” to view inside the box.

Nesting Box Results

Year # of Boxes

       Nests

Eggs Young Fledged Fledged per Occupied Box
2013 1 0 0 0 0 0
2014 3 2 10 9 9 4.5
2015 8 5 26 7 7 1.4
2016 9 7 36 30 26 3.7
2017 9 8 40 24 23 2.9
2018 9 8 39 32 26 3.2
2019 9 7 34 24 20 2.8