(J. G. Cooper, 1861)
The Elf owl (Micrathene whitneyi) is a small grayish brown bird about the size of a sparrow found in the Southwestern United States, central Mexico, and the Baja California peninsula. It has pale yellow eyes highlighted by thin white “eyebrows” and a gray bill with a horn-colored tip. The elf owl frequently inhabits woodpecker holes in saguaro cacti; it also nests in natural tree cavities. It is nocturnal and feeds primarily on insects.
Elf owls usually choose abandoned, north-facing woodpecker cavities in saguaro cacti, sycamores, cottonwoods, and other hardwood trees, to raise their young. While some cavity nesters utilize vegetation as nesting substrate, elf owls have been observed removing this vegetation and prefer a bare cavity. While three eggs is a very common clutch size, females may lay anywhere from one to five eggs in springtime (late March to early May). The eggs are usually round or oval shaped with a white coloration and are from 26.8 x 23.2 to 29.9 x 25.0 mm in size. The eggs are incubated for about 3 weeks before the chicks hatch. The young owlets fledge at about 10 weeks. Usually, chicks are born in mid-June or early July. By the end of July, they are almost always fledged and ready to set out on their own.
Appearance and Behavior
It is the world’s lightest owl, although the long-whiskered owlet and the Tamaulipas pygmy owl are of a similarly diminutive length. It is also the world’s smallest owl. The mean body weight of this species is 40 g (1.4 oz). These tiny owls are 12.5 to 14.5 cm (4.9 to 5.7 in) long and have a wingspan of about 27 cm (10.5 in). Their primary projection (flight feather) extends nearly past their tail. They have fairly long legs and often appear bow-legged.
They are often found in chaparral, and are easily found during their breeding season. During dusk and just before dawn are the times this owl is most active, they can often be heard calling to one another just after dusk or at sunset in a high-pitched whinny or chuckle. Hunting is performed mostly during nocturnal hours. Straight line flight is often deployed for this purpose but they will use an arced flight when in the vicinity of the nest and for flying to and from perches. They live in cacti much like some birds, using the shade and climate the cacti provide.
Elf owls feign death when handled, an adaption the encourages a predator to relax its grip so that the owl can escape. Territories are established by the male and are defended by both the male and the female. This is done through the use of song. During the breeding season, elf owls are monogamous and stay in breeding pairs, but can be found in small groups during migration and when mobbing predators. Adults as well as young can be subject to predation by other predatory birds such as jays, hawks, and owls.
The Elf Owl migrates to the southwest United States; California, Arizona, New Mexico, and Texas, in the spring and summer for breeding. In the winter, it is found in central and southern Mexico. Migrant elf owls return north in mid-April to early May. Resident populations occur in a couple of places in south central Mexico and along the Baja peninsula.
Elf owls feed mainly on insects, so they occupy habitats with a ready supply of them. Agaves and ocotillos are ideal places for foraging, as moths and other insects may be found in their flowers. In urban areas they can be seen utilizing outdoor lights that attract bugs as areas for insect hunting. They are often seen chasing after flying insects, with a flight similar to a tyrant flycatcher‘s. They also feed on scorpions. Once the owl has killed the scorpion, they can be observed removing the stinger before consumption. The elf owls seem to not be bothered by scorpion stings. They feed primarily on invertebrates such as moths, crickets, scorpions, centipedes, and beetles. They will also feed on small mammals, reptiles and birds.
Elf owls live 3 to 6 years; in captivity they may live up to 10 years. The most common types of mortality for these owls are predation, exposure, and inter-species as well as intra-species competition.
These subspecies are currently recognized:
- M. w. graysoni Ridgway, 1886 (extinct)
- M. w. idonea (Ridgway, 1914)
- M. w. sanfordi (Ridgway, 1914)
- M. w. whitneyi (J. G. Cooper, 1861)
M. w. idonea, the subspecies in southernmost Texas to central Mexico, is resident, as are the isolated M. w. sanfordi of southernmost Baja California and M. w. graysoni (Socorro elf owl) of Socorro Island, southwest from the tip of Baja California. The Socorro elf owl apparently became extinct in the late 20th century, probably around 1970.