American Kestrel

The American Kestrel is the smallest falcon of North America. It occurs throughout the Western Hemisphere except the Amazon Basin and the Arctic, although within this expansive range it is less common in areas with extensive tree cover. Kestrels are birds of open country, historically nesting in old woodpecker cavities and hunting birds, rodents, and insects in short vegetation. They usually do this from a perch, but where those are rare kestrels are often seen hovering over fields instead.

Formerly widespread and common in New Hampshire, kestrel populations have been in gradual decline since the 1960s. This trend is not unique to the Granite State, and some estimate that North America has lost half its kestrels in that time frame. But while the trends are clear, the reasons for them are far from it. It’s likely that habitat loss, from development or reforestation, is part of the problem, but this doesn’t fully explain the absence of kestrels from apparently suitable areas, including much of their former range in New Hampshire. Other theories involve the effects of pesticides (on both kestrels and their prey), more intensive agriculture that has eliminated nesting snags and the hedgerows where kestrels often hunt, and even predation by increasing species like the Cooper’s Hawk. So far, no one’s been able to come up with clear answers.

One way to help kestrels is to put up nesting boxes, which the birds readily take to, and there are several coordinated efforts to do this in New Hampshire and surrounding states. If birds use a box they often produce young successfully, suggesting that there’s not a problem with local food supplies. What we don’t know is whether fledged young encounter threats later in their first migration and winter that they are unprepared for. In addition, box use is often low, with many unoccupied despite being in suitable habitat. This again suggests problems with overwinter survival, there are fewer “new” birds” despite successful breeding.