Blane Klemek: Adaptable kestrels probably the most observed raptor
Some people still call a favorite little raptor of mine “sparrow hawk”. And for many years I did as well. And though to the untrained eye she appears to be every bit a hawk that shares traits common to the group, the pint-sized bird-of-prey is not a hawk at all. In fact, the sparrow hawk is a falcon: the American kestrel.
This classy little falcon is as easy to misidentify as, I think, it is to identify. Perched upon a power line, she appears to be a dove from the distance, or some other similarly sized bird. But on the wing she assumes the beauty and grace of which can only be ascribed to falcons. Narrow and pointed wings power her through the air with such commanding speed, that few birds can outdistance or outmaneuver her.
A familiar kestrel habit will often give human admirers a positive clue. Kestrels typically hunt by hovering in near motionless, save for their fluttering wings, above grassy fields, ditches, or other likely small-rodent haunts. Her longish tail will be fanned, the body angled slightly upward, and her head tilted downward with eyes intensely riveted and searching for the movements of voles beneath tall vegetation.
Aided by headwinds, this mode of flight will be maintained indefinitely, occasionally dipping abruptly a few feet lower in altitude, only to regain the sedentary airborne posture if prey had yet to be sighted or secured. A complete free-fall to the ground below will occur if a hapless vole, mouse, or grasshopper fails to miss the clutches of the falcon’s quick strike.
In 1922, Floyd Bralliar wrote of his observing a kestrel striking a bird at rest upon the ground. He described it as a wonderful sight of such rapidity that, “ere a man hath power to say, Behold” it is over with. He added after watching the kestrel’s swooping dive, flashing wings, and the falcon’s sudden departure with its prey, “So quick [that] bright things come to confusion.”
Several years ago a pair of kestrels took notice of one of my wood duck nesting boxes that I had nailed to an oak overlooking Lake Assawa. Even before I took pleasure in viewing the eloquent couple, I listened to their cries. A flicker-like call, or, in some ways, a cry suggesting a species of shorebird: qui, qui, qui, qui, qui, qui, qui, etc.
Then, during the spring of 2011, another pair, possibly the same pair, took up residence in another artificial nest box that I had built specifically for kestrels — a smaller box with an entrance hole of dimensions that kestrels supposedly prefer. The pair courted and began nesting; soon after the hen laid five eggs and began incubating them.
All five chicks hatched, albeit asynchronous, but were growing well and seemed content together in the nest box as they waited for their parents to capture and bring them food. However, by early July, conditions began to deteriorate. And as the month wore on a heat wave that had begun during the first week of July stretched well into the latter part of the month.
My occasional check-ins on the nestlings was stressful, for I could clearly see that the young birds were extremely uncomfortable because of the heat and close confines of the nest box. Moreover, I believe the parents were having difficulty in finding prey; further adding to stress levels of the chicks. But Nature has a way with many species of raptors to increase the odds that survival — for some — is possible.
On one particular day when I climbed the ladder to check on the kestrel family, I was surprised to discover that three of the five chicks (now almost ready to fledge), were gone. At first I wondered if three hadn’t already fledged, but the stark truth became evident as I examined the inside of the box. The remains of three kestrels lay about inside the nest box, while two surviving but very healthy looking nest mates watched me closely.
In this particular case, the two surviving kestrels possibly killed their siblings and consumed them. Or at the very least, they fed on their bodies after they had perished. Whether they killed their nest mates or not, it was apparent that the survivors were no longer suffering, but were now well fed and more comfortable in a less crowded nest box. Common amongst raptors during unfavorable conditions, the surviving kestrels had engaged in what ornithologists term as “siblicide”, thus increasing the chances that one or more chicks survive to fledge. Indeed, the remaining kestrels fledged a short time later.
American kestrels are beautifully colored falcons; no other bird of prey in North America is so richly painted. Male kestrels sport a rusty back and tail, slate blue adorns his crown and wings, and a white terminal band tips his tail. White cheek patches are accented by two black “whisker” markings on each side of his head. Total length is about ten inches long and averaging slightly less than four ounces in weight. Not much for size, but any shortcoming is compensated by force and fearlessness.
Unique to most hawks, falcons, and eagles, the little “sparrow hawk” is fairly comfortable nesting in urban settings and backyards. The kestrels’ acceptance of artificial nesting boxes, abandoned woodpecker holes, and the crevices of buildings as nesting sites bespeaks of its extraordinary adaptability and tolerance of human presence. Couple this with the species frequent occurrence along roadways as they hunt for prey, kestrels are probably the most often observed raptor as we get out and enjoy the great outdoors.
(Klemek is a DNR Wildlife Manager. You can contact him at firstname.lastname@example.org.)