Rigor Vitae: Life Unyielding

Thursday, April 06, 2006

VANISHING OWLS OF THE WASATCH—PART I

In Utah's Wasatch Mountains, spring is elusive in early April. The other day I was hiking comfortably in a t-shirt at noon—by 2pm it was snowing sideways. The same songbirds I see now have been in evidence all winter, and forget about seeing reptiles or amphibians. Still, a sign appears here and there: blooming Glacier Lilies (Erythronium grandiflorum) poke through the shallow snow on the hills' warm sides, and many of the big birds are thinking seriously about breeding. At dawn the area's small Sage Grouse (Centrocercus urophasianus) population congregates to display on their leks. Turkey Vultures (Cathartes aura), Golden Eagles (Aquila chrysaeotos), Ferruginous Hawks (Buteo regalis) and Prairie Falcons (Falco mexicanus) are all getting amorous. Great Horned Owls (Bubo virginianus), the earliest of all our birds, are mostly well into incubation, and normally their nocturnal breeding calls are replaced this time of year with the eerie wailing of Long-eared Owls (Asio otus), once the commonest large owl of the Wasatch. Roughly two-thirds the size of a Great Horned Owl, the Longear's huge, lanky wings make her look far bigger in the air. A pair of dark-rimmed lemon eyes closely set in the center of a ruddy disk of a face give the bird a permanently flabbergasted look, though her mobile facial feathers and ear tufts give her a range of expressions within the bounds of flabbergastion. Those long ear tufts also disrupt her shape and help her to assume the appearance of her surroundings.

Usually thought of as a forest bird, the Longear is indeed mostly seen in dense trees, where she prefers to sleep and to nest, but at night much of her time is spent in open country. Here in the Wasatch, the birds usually nest in an old Cooper's Hawk (Accipiter cooperi) nest in a dense grove of Bigtooth Maple (Acer grandidentatum) or in a thick Gambel's oak (Quercus gambelii) clone, where an old Black-billed Magpie (Pica hudsonica) nest is usually appropriated. I've never found one nesting in a conifer, but I credit this solely to the difficulty of finding such nests. Three to nine eggs are usually laid in April or May, and incubation begins as soon as the first egg is laid, so the brood always shows a range of ages. The hen sits very tight on the nest, and continually broods the young until they're quite large. If an intruder climbs the nest tree, she usually waits until the last minute to leave. At that point she will call her mate in, and both birds will perform displays of intimidation that are as spectacular as any in the bird world. Longears are often very aggressive; I've been hit and raked by them many times. Perching but a few feet away, they will face their foe with feathers puffed and wings spread and rotated forward so as to present the largest possible surface of avian fury. Swaying to and fro, and emitting a repertoire of hoots, shrieks and demonic wailing that would embarrass Yoko Ono, they are as frightening as a ten-ounce bird can possibly be. Occasionally one will drop to the ground and engage in a broken-wing display, or even pounce into deep grass and produce squeaks like a dying rodent to lure away the threat.

From what I've seen, the birds around here hunt mostly in sagebrush meadows, where they course about at low altitude, searching for voles (Microtus spp.), pocket gophers (Thomomys spp.), and other small mammals in much the same manner as their more diurnal cousins, the Short-eared Owls (A. flammeus). The flight is harrier-like, but even more buoyant, with the body bobbing up and down with each stroke, the wingtips almost appearing to remain level while the body flaps up and down. Like that of many other birds that breed in the Wasatch Mountains, the winter migration of Long-eared Owls is more elevational than geographic. Most of our birds winter in the desert plains to the west, where I am told they feed largely on Desert Cottontails (Sylvilagus nuttallii), a powerful and dangerous prey that more than doubles the owl in weight. I've never seen a Longear kill large quarry, but I assume it's done in the typical owl fashion: the victim clutched firmly with both feet and bill, and the bird hanging on for dear life, in a semi-comatose state until the struggling subsides to the point where the prey can be dispatched. Like Great Gray Owls (Strix nebulosa) and some other species that spend much of the night flying low over fields, Long-eared Owls are very vulnerable to car traffic. While driving across the Nevada desert last September, I counted 27 freshly-killed Longears on a 70-mile stretch of highway.

Sadly, these once common birds seem to have all but vanished from my study area in the Wasatch. Raccoons (Procyon lotor), introduced in the 50s and 60s, have increased in tandem with the human population, and no creature has been hit harder by them than the Longears. In the late 70s I began seeing their nests raided by Raccoons, and within a few years virtually none escaped the masked rascals, which eat the eggs, the young, and even the incubating hens when they can catch them. For a while I worried that I was leading Raccoons to nests, but it seems that A. otus is particularly vulnerable to the carnivores with or without my help. Perhaps there is an attractive scent about the nests.

In the summer of 2004 I found the first successful Longear nest in my study area in 20 years, from which four young birds were successfully fledged. How they evaded the Raccoons is beyond me, but I hope it marks a trend. Last year I was disappointed to find the nest unused. I'm tempted to hike up there tonight to listen for courting owls, but rather than take a chance of disturbing them, I'll wait until late May, after the danger of stressing an incubating owl is over. Once that time comes, a no-holds-barred search for Longear nests will be in order.

In the second half of this post I'll discuss the other local owl that's seen a dramatic decrease in numbers recently, the beautiful little Flammulated Owl (Otus flammeolus).
___________________
illustration: LONG-EARED OWL PORTRAIT (2006) acrylic 15" x 7"

7 Comments:

Anonymous Cindy said...

long-eareds are becoming quite a rarity in Michigan.. same old story, loss of habitat.
As always, I love the painting :)

5:42 PM  
Blogger Money Maker said...

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11:57 PM  
Blogger cpbvk said...

Thanks, Cindy. I'm surprised to hear they're succumbing to habitat loss. Is that forest loss? I would expect that an increase of forest edge would benefit them. Out here they don't seem to like to live too close to humans, though. Last night I heard a pair of courting Longears. Sadly, I also saw two raccoons in the same area.

12:59 PM  
Blogger wolf21m said...

Thanks for the post. I am sorry the news is so bad. I haven't seen any long ears here in Boise Idaho, not sure if they were common at one time or not. We do have a number of successful Great Horned Owl pairs. Hopefully they will stay safe from the Racoons, I know that my yard is not.

3:21 PM  
Blogger cpbvk said...

A friend of mine found a nesting Longear colony near Boise twenty some-odd years ago. It would be interesting to see if it's still active. The phenomenon of gregariousness in that bird is interesting. I've never found them nesting in groups, but have often found groups of them in the winter. Down here the Great Horneds are doing great. The 'coons don't seem to be much of a problem for them.

7:23 PM  
Blogger sexy said...

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11:09 PM  
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