species nests exclusively in saguaro cacti.
A female lays two to five eggs, with the average clutch size increasing further north and inland. Incubation lasts twenty-six days, and the chicks fledge after another thirty-five days. Meanwhile, the male provides food and defends the nest aggressively, attacking trespassers with angry bill snapping and raking of talons. The hatching is synchronized with the spring northbound bird migration, so the parents have a good supply of small exhausted songbirds with which to supplement the diet. The chicks continue to receive their parents’ care for five to six weeks after fledging, before they disperse ready to establish their own breeding territory the following spring.
One interesting detail in this bird’s nesting arrangements, and one that it shares with the Eastern Screech Owl, is the male’s habit of collecting blind snakes and depositing them alive into the nest. These diminutive reptiles lurk among the debris at the bottom of the hole, where they feed on flies and parasites, and thus help keep the nest hole clean and healthy.
With an estimated population of 700,000 individuals, the Barred Owl is classed as Least Concern. It has suffered localized declines due to habitat loss, pesticides, and the westward spread of the Barred Owl, but in recent years the Western Screech Owl has offset this to some extent by moving into built-up areas. It takes readily to nest boxes, which helps considerably.
Owls, including this species, have proportionally the largest eyes of any birds.
Snakes and other reptiles often fall prey to this species.
A Western Screech Owl fluffs out its feathers for warmth.
An Elf Owl peers from its nest hole in a saguaro cactus, a plant to which its fortunes are closely tied.
ELF OWL
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.
SPOTTED OWL
STRIX OCCIDENTALIS
APPEARANCE
Robust, medium-size, with round head, no ear tufts, and relatively long tail; upper parts dark brown with pale spots; under parts graduate from brown and whitish barring on upper breast to heavy white spotting lower down; flight feathers and tail heavily barred; eyes dark brown/black in buff facial disk with dark rim.
SIZE
length 17 in. (43 cm)
weight 1.3 lb (600 g)
wingspan 45 in. (114 cm)
females larger than males
DISTRIBUTION
Pacific North America, from southwestern British Columbia south through western Washington and Oregon to southern California; also Rocky Mountains, from southern Utah and Colorado south through Arizona and northwestern Texas into central Mexico.
STATUS
Near