2015 April – Commonly Uncommon

cont…

greg-long-eared-owl

Our “common” falcon may be the colorful little American kestrel, because it is not only widespread but prone to settling down on telephone lines in neighborhoods everywhere, not much different than any other small bird. If there is a “common” owl in the United States, it is most likely the great horned owl, the big, powerful, and widely ranging raptor that dominates evenings in Arizona and throughout the country. But just because these birds are commonly seen, doesn’t mean that they are the only ones around. There are raptor species in Arizona that are among the most widespread birds of prey in the world, yet most people don’t know that they even exist. “Common” and “conspicuous” are two very different concepts, and though they might not be very conspicuous at all, two of our state’s owls, the long-eared and short-eared owl, are among the most widely represented of their kind, anywhere.

The long-eared owl and the short-eared owl are similarly sized, 15-16 inches long and weighing up to a pound. Their names are somewhat misleading, in the same way that the great horned owl’s name is misleading: when an owl’s name references “ears” or “horns,” it’s typically in reference to the prominent feather tufts that many owls have on their heads, tufts that add a definite eared or horned look to their silhouette. The presence, absence, or prominence of feather tufts can aid in the identification of owl species or in discerning them from one another. The long-eared owl is named for its tufts, but its real ears are critical to its survival. Its ear openings are asymmetrically placed on the sides of its head, and the slight difference in position gives it an aural acuity that human beings can’t even dream about. Long-eared owls are true nocturnal hunters, and their faces feature two exaggerated disc shapes around their eyes, which help them pinpoint the source of incoming sounds with incredible accuracy. If this tactic seems familiar, it is because the far more famous barn owl, also a disc-faced, purely nocturnal hunter, operates in an identical fashion. The long-eared owl flies back and forth through its domain, listening for the sound of movement and using its incredible hearing to home in on scurrying rodents. The special feathers that allow owls to fly silently grant the long-eared owl a final edge: predator and prey may not be able to see each other, but if only one can hear the other, that one has a huge, and typically decisive, advantage.

The short-eared owl, by contrast, is a more traditional owl, operating in low light instead of no light. We usually think of owls as creatures of the night, but many do their best hunting at dawn or dusk, when the sun’s rising or setting rays provide just enough illumination to complement the owl’s superior ability to see in the dark. The short-eared owl is one such predator, and its preferred hunting time, coupled with the fact that it favors wide open territory instead of dense forests like the long-eared owl, means you are more likely to come across it than its longer-eared cousin. The short-eared owl makes use of both sight and sound to find its prey, and it can be readily spotted by its erratic, up-and-down hunting flights, which the National Audubon Society compares to “looking rather like a large moth.” Rodents are its bread and butter, and short-eared owls have been known to dynamically migrate in order to keep up with varying prey populations. Unfortunately, since the wide open spaces they live in are also valued heavily by man, the increasing urbanization of flatlands is beginning to take its toll in some areas.

Despite this sad reality, one faced by animals of every size and shape, these two owl species are nonetheless incredibly prolific, found throughout the Americas, in Europe and Asia, and on many islands in between. The great horned owl may be Arizona’s most “famous” representative of its kind, but its range, while extremely diverse, is limited to the Western Hemisphere; these two “lesser known” owls are in fact denizens of the entire world.

It simply goes to show, that you don’t have to be obvious to be everywhere.

References:
http://www.audubon.org/field-guide/bird/short-eared-owl
http://bna.birds.cornell.edu/bna/species/062/articles/introduction

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