Naturespeak A naturalist's view of the world

January 31, 2010

High Wire Act

Filed under: Uncategorized — wykes @ 9:10 pm

Chances are pretty good that if you spot a solitary bird perched high on a telephone wire it will be a kestrel. You’ll be able to identify it even before you get a good look. The odds for early I.D. are improved if that wire is along a country road and almost guaranteed if they are situated in a weedy right of way. Oh, there are plenty of high wire birds out there during the winter. Mourning Doves, Starlings, and even overwintering bluebirds all will sit upon the highwire, but the key to this discussion is the word “solitary.” These other guys tend to flock together as birds of a feather. Kestrels are loners during the wintertime.

Kestrels make so much use of telephone lines as hunting perches that it is fair to say that these two entities are inseparable. They are rarely seen without them (although it doesn’t work the other way around – there are plenty of telephone poles without falcons attached to them). Although I can’t verify this, I’m fairly sure that this relationship stands true throughout the bird’s extensive range. I came upon this high wire kestrel while on the way to Moscow, for instance. O.K., it was on the way to Moscow, Michigan, but my point is still valid.

These birds can be found all the way from Alaska and northern Canada to the very southern tip of Chile. From the land where they are called Crecerelle d’Ameriques  to the southern hemisphere where they are called Cernicalo Americanos, American Kestrals are creatures of lofty vision. I am admittedly ignorant of the number of telephone wires in Chile and the Northwest Territories, so I’d better qualify my remarks by saying this thought only applies in areas “where telephone lines are present.” Perhaps Llamas would do as substitute perches in South America.

From a distance, removing the presence of the wire perch for a moment, the familiar outline of these robin-sized falcons is diagnostic enough (see above). They sit like tiny hunchbacks as they steadily scan the ground below for mice. Creatures of nervous habit, kestrels frequently bob their tails up and down when on the hunting perch. They betray their inner energy by tail bobbing in the fashion of a stalking cat twitching only the end of its tail. I counted the tail bobs of a wire-perched bird the other day and found that the individual flicked his tail no fewer than 72 times per minute. That’s more than once per second. This bird was aware of my presence and was likely showing a little more anxiety than usual. I do tend to elicit that same reaction in people as well.

Up close, the birds present a dazzle of color to add to their familiar profile. Male birds, like the one pictured here, have rich blue-gray wing coverts and rufous tails.  The females are heavily barred all over, even on their tails, and lack the blue-gray portions. All individuals have striking black facial marks – called mustaches on the males and well…, the same thing on females (I have seen old Italian women with mustaches, so there is some precedent for this). You know, now that I think of it, I probably make people nervous because I say things like I just stated. But, this isn’t about me, is it. It’s about Kestrels, so let’s get back to the subject at hand.

During the winter months these colorful falcons concentrate on meadow voles (mice), shrews and a few small birds as target prey. Of these, however, the voles are at the center of the target. There is no better vole habitat on earth than the grassy areas found along those Kestrel infested power line right-of-ways. Kestrels are very good at nabbing voles. They drop down onto their selected prey, clutch it in their powerful little talons and return to the power line for a power lunch. This is not the only hunting method employed by the kestrel. They are expert hang gliders as well, but we’ll leave topic for another time.

Whether by dropping down from a telephone line or a stationary aerial station, the birds descend upon the mice from above. You’d think that meadow voles would catch onto this scheme, but they don’t. They are content with the fact that Kestrels, like all predatory birds, miss a great majority of the time. I’m not sure why I found it funny, but I found this quote from an Ohio Journal of Science article published in 1982. The piece was talking about how meadow mice don’t look up that much. I quote: “Microtus (meadow voles) are usually under protective cover and don’t see aerial predators, and thus have not developed precise aerial predator detection capabilities.”  These are sweet words of reality for a wire perched Kestrel.

3 Comments »

  1. Power lunch? Groan. Great post, though. I used to work with a kestrel (trained to come to the glove, etc.), so I’m rather fond of these small falcons. Don’t see them much here in the mountains, though – we get merlins instead.

    Comment by Ellen — February 2, 2010 @ 4:44 pm

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