In the past several decades, researchers have become increasingly alarmed at dwindling numbers of North America's smallest falcon, the American Kestrel. But thanks to an expansive nest box program coordinated by Madison Audubon volunteers, 2016 may be a banner year for these little-but-fierce flyers.
The decline of kestrels, once-common hunters around south-central Wisconsin's prairies and woodlands, is thought to be primarily caused by a lack of nesting habitat. These cavity-nesting birds rely on dead trees and abandoned woodpecker holes to raise their brood, but the common practice of clearing dead standing trees has hit this species hard. Across the country, their numbers are dwindling. Thankfully, kestrels are adaptable - the small raptors love nesting in man-made boxes. That's where Madison Audubon members come in: for 30 years, MAS staff and volunteers have been maintaining (and expanding) a kestrel nest box trail throughout south central Wisconsin. The Madison Audubon trail now boasts 132 nest boxes and is considered the largest kestrel nest box program in Wisconsin.
Brand Smith, past MAS president and volunteer kestrel box coordinator, stated that this season's volunteers have found over 40 nests in the 134 boxes! In 2015, 29 boxes contained nests. This marked increase is a huge success for breeding kestrels in the region.
Madison Audubon partnered with Central Wisconsin Kestrel Research's Janet Eschenbauch, Maureen Brocken, and Gerry Janz to band this year's young. Janet and her colleagues at CWKR coordinate a 56-nest box kestrel trail in the Buena Vista Wildlife Area in Portage County, continuing the work of legendary researchers Fran and Fred Hammerstrom. In addition to banding kestrel young, Janet is also banding any adult kestrels in the nest boxes to learn more about site fidelity.
So far, Janet has banded 93 chicks and three adults from Madison Audubon's nest boxes! The average kestrel clutch size is four to five, and Janet is observing healthy and abundant chicks this year, perhaps thanks in part to an abundant small mammal population this spring. Kestrels as young as five days old can be banded, since their legs are large enough to hold a band and the future width of their legs will not increase much.
In addition to measuring, weighing, and banding the birds, Janet removes one breast feather from one bird per box to send to The Peregrine Fund. The Peregrine Fund Kestrel Project is looking at the genetic makeup of kestrel subpopulations so they can learn how climate change may affect them, and also to see differences between populations throughout the United States. About 20 feathers are needed for a genetic sample.
More than thirty of the young that were banded were from the six boxes located on Goose Pond Sanctuary properties. Be sure to look for kestrels perched along electrical lines near their nest boxes when you visit Goose Pond this summer!
Thanks to our kestrel nest box volunteers and for the generous support of Madison Audubon members who make this program a possibility.