Kestrels in Our County
Yolo County’s smallest and most familiar falcon, the American kestrel, has been declining in numbers across its wide North American range in recent years. There is some evidence that it is losing ground locally as well. In natural situations, kestrels nest in tree cavities in or at the edge of wide-open spaces. It is probable that nest holes are in short supply, both because safety concerns prompt us humans to remove holey tree limbs, and because ever-aggressive starlings compete with kestrels for the remaining ones. Here I report on a marvelous local effort to provide nest boxes to give kestrels a better chance.
Three years ago, Yolo Bird Alliance member Kevin Hunting and City of Davis wildlife specialist John McNerney installed ten boxes in spots on City of Davis property that looked auspicious—in the open spaces of fields or grasslands, with kestrels present and tree cavities absent. They chose sites with security and good access. Later they expanded to include properties restricted by conservation easements that keep them in open space.
American Kestrel ©Erna Tarara
This spring, at the start of their fourth season, the duo has made twenty-six boxes available. They plan to monitor all of them for occupancy by kestrels, presence of eggs and young, and fledging success. Earlier efforts yielded one or two successful nests per season, but 2024 was a disaster. Long periods of extreme heat were likely to blame for the death of all nestlings. Unsurprisingly, a similar nest box project in Napa, Solano, and Yolo counties also experienced heat-related mortalities in the latter part of the season in their Yolo county boxes. So now the work involves exploring redesigning the boxes to include heat protection, such as better insulation and air venting, and box placement that offers some shade in the afternoon. They will also put tiny temperature monitors in some nests.
They use a scope and camera to peer into the boxes from the ground. They would like to furnish at least one nest with a video camera that can be viewed remotely so as not to disturb the birds. Boxes are placed ten to fourteen feet above ground; you need a ladder. This is important because, in my experience, boxes at arm’s reach can be vandalized.
All said, this is a lot of volunteer work. There may be opportunities for Yolo Bird Alliance members to help. At the least, report kestrel use of local boxes to John McNerney or Kevin Hunting. Both men are mines of information about these birds. To learn more about efforts to help American kestrels that use nest boxes, visit Cornell University’s NestWatch program at nestwatch.org.
–Michael Perrone, Conservation Chair