American kestrels fight for winter survival

Jan 5 2010 - 6:44pm

Images

Paul Higgins courtesy photo
A male American kestrel finishes a deer mouse at Farmington Bay Waterfowl Management Area on Christmas morning, 2007.
Paul Higgins courtesy photo
A male American kestrel finishes a deer mouse at Farmington Bay Waterfowl Management Area on Christmas morning, 2007.

All parts of a bird except the distinctive bobbing tail were hidden behind a light fixture atop a pole as I pulled into the Riverdale Target parking lot. That meant the smallest falcon in North America, an American kestrel, had just landed on the fixture and was regaining its balance post-flight.

Kestrels are the most common raptor in North America. They're a familiar sight along roadways and are especially visible perching on power poles and on wires perfectly sized for their tiny feet. While their summer diet is high in insects such as grasshoppers and dragonflies, they can take songbirds and subsist mostly on small rodents in the winter.

I only got a second or two to see the whole light-fixture bird when I repositioned because the falcon dropped from the pole and bee-lined toward another behind the store and along I-84.

It was a male. His slate blue wings spotted with black contrasted with his bright rust back and tail as he flew away.

American kestrels are not only the tiniest falcon at a mere nine inches from beak to tail, but they're the most colorful, too. In addition to the males' blue and rust upper parts and the females' rust upper parts, both birds' foreheads are slate blue, their crowns rust, and their breasts and bellies a soft buff spotted with black (the males) or smudged with rust (the females).

It's hard not to be impressed with the beauty of a kestrel when seen close and in bright light, revealing all the colors.

My parking-lot bird dipped low and flared up to the next light fixture, and a small dark object dropped from the pole to the snow below. A great flapping of two pairs of sharply pointed wings ensued. Two kestrels were struggling with each other and then dropped to the ground like a stone, locked together as they grappled, prey forgotten.

The male landed on his back, wings open. The second bird, a female, pinned him from above while extending her wings and flaring her bright rusty tail against the snow. Their talons were likely still locked.

Both birds wore aggressive faces with beaks open. The dark marks on their heads, including the characteristic falcon black mustaches that appear to drip down the sides of their faces, were obvious as they remained rigid.

More struggling caused them to begin sliding down the snowy embankment, the male serving as a toboggan for the female. They stopped in just a foot or so. The male wrenched away and took to the air again, returning to one of the light poles in the parking lot.

I suspect I had just witnessed a survival struggle. The male kestrel, known to be more intensely territorial in the winter, challenged a female that was hunting successfully in his territory. She could even have been his mate, but the realities of winter survival make that point moot. While kestrels might sometime share winter territories, more birds in a territory also means less prey for each, and it was in his best interest to drive her away.

When the male attacked the female, she dropped a small vole she had likely caught along the roadside. But from the moment the female defended herself, things went badly for the male. He was the underdog.

Males of all our North American raptor species are smaller than the females, giving the girls the advantage in combative encounters. A female kestrel is about 10 percent larger than her mate. Males usually avoid physical fights like the one I witnessed, perhaps because the results are predictable. Not only did he lose the skirmish, but he also didn't get the prey.

In addition to maintaining territories and challenging intruders, another survival tactic kestrels use is to cache uneaten food for later. This past summer, I watched a kestrel cache a tidbit along Snowbasin Road. He landed atop a spruce spire, tail bobbing as he surveyed a grove of aspens, one of which probably housed his mate and their young in an old woodpecker hole. When he flew, a blob in his talons became obvious. The bird landed on another spruce rusty with dead boughs, plucked the item from his foot, tucked in into the dead foliage and flew away.

That sighting represented a time when both male and female not only shared the same territory, but the male provided food to the female and the brood as the parents teamed up for their survival. Until the warm weather returns, it's each bird for him or herself.

Kristin Purdy can be reached at gobirding@comcast.net.

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