Читать книгу A Parliament of Owls - David Tipling - Страница 15

MICRATHENE WHITNEYI

APPEARANCE

Tiny, with round body and large round head with no ear tufts; faint facial disk, strong white eyebrows, and yellow eyes; upper parts brown, with pale blotches and scalloping that grades to barring on flight feathers, and strong white scapular line on shoulder; breast pale with soft, broad, rufous-brown streaks; in flight, shows short round wings.

SIZE

length 4.9 – 5.7 in. (12.5 – 14.5 cm)

weight 1.4 oz (40 g)

wingspan 10.5 in. (27 cm)

females larger than males

DISTRIBUTION

Southwestern United States, from Arizona, New Mexico, and southeast California south to northern and central Mexico; separate population in southern Baja California.

STATUS

Least Concern

THIS POCKET PREDATOR IS the world’s smallest owl. No larger than a sparrow, it is lighter on average than any other owl species. However, what it lacks in size it more than makes up for in charisma. Its intense face, peering from a hole in its spiny cactus citadel, is one of the bird world’s most distinctive.

This is an owl of arid terrain; it ranges across the semideserts and chaparral of the southwestern United States. This breeding population migrates south and east to winter in Mexico, where it finds a more abundant insect supply. A separate population in Baja is sedentary. In pure desert habitat, the Elf Owl is strongly associated with the saguaro cactus, a giant that towers up to 42 feet (13 m) and thrives across the uplands of northwest Mexico, where this owl is abundant. Elsewhere, it inhabits lightly wooded desert fringes and scrublands, from canyons up to mountain slopes. In winter, with no need for breeding trees or cacti, it often moves to more open ground.

The Elf Owl is nocturnal, roosting by day in holes or, on its winter quarters, among low ground vegetation. At dusk, it sets out to hunt, flying low in search of prey. The staple diet comprises large arthropods, ranging from crickets and beetles to spiders and scorpions. In flight, it appears tiny, its short round wings no wider than the span of some tropical butterflies. However, this owl is adept at capturing winged insects in the air, either sallying out from a perch flycatcher-fashion or hovering until the prey takes flight, then snatching it with deft talons. The Elf Owl lacks the sound-dampening feather adaptations of most owls, as the insects on which it subsists are not alerted by sound. Indeed, in flight it is one of the most audible of owls. It may occasionally also capture vertebrates, including small rodents, snakes, and reptiles. In general, this owl’s diet reflects both location and season: in the midsummer rains, for example, the Elf Owl takes advantage of the mass emergence of beetles from their underground pupae.

Like many migratory birds, the Elf Owl seldom sustains a pair bond beyond one season. For migrants, courtship starts when the males return to their breeding grounds in late February. On moonlit nights, they deliver their squeaky chuckle of a song enthusiastically from exposed perches. Once a female arrives, the male moves into a potential nest hole to entice her closer. Soon the pair is duetting as she checks out all potential nest sites around the territory. At this stage, they spend much time preening one another and copulating.

Nest sites are invariably woodpecker holes. The female lays an average of three eggs and starts incubating from the second. Incubation lasts twenty-one to twenty-four days, after which the male provides food at a frantic rate—as often as one item per minute—while his mate broods the chicks. The young can catch their own insects immediately after they leave the nest. When nesting in saguaro cacti, this species has the highest breeding success rate (70 percent) for any North American owl, largely because the spines help to deter any would-be mammalian nest raider. It is not aggressive when defending its nest, however, preferring flight to fight. Females may even feign death if surprised inside the hole.

The Elf Owl has an estimated population of 190,000 and is classified as Least Concern. However, it is vulnerable to loss of food due to pesticide use, and also to competition for its nesting holes, especially from the introduced European starling (Sturnus vulgaris). It may live six years in the wild and up to ten in captivity.

An Elf Owl returns to the nest with insect prey for its young.

Old-growth forests, festooned with mosses and lichens, are prime habitat for this threatened species.