Elf owls primarily eat insects — especially moths, beetles, and crickets — but occasionally they eat small mammals and reptiles, like spiny lizards, earless lizards, blind snakes and kangaroo rats. In southeastern Arizona, elf owls change their diet based on the weather. They eat mainly moths and crickets until the summer rainy season begins, then they switch to scarab beetles. Elf owls employ a sit-and-wait strategy when foraging. They search for food on the ground, in the air, and in lower to mid-level vegetation. In urbanized areas, they forage by outdoor lights, lighted windows and at hummingbird feeders. They can catch insects in flight, capturing them with their feet or beak. Sometimes elf owls chase insects on the ground and beat them from plants. Elf owls move their food back and forth between their feet and beak in order to kill, pluck, and/or eat it. They avoid consuming dangerous body parts of prey; they remove the stingers of scorpions before eating them. Elf owls cache large prey in cavities in order to eat them at a later time.
Animal Foods: mammals; reptiles; insects
Foraging Behavior: stores or caches food
Primary Diet: carnivore (Insectivore )
Adult and fledgling elf owls face predation by great horned owls (Bubo virginianus), mexican jays (Aphelocoma ultramarina), and probably by Cooper’s hawks (Accipiter cooperii). Eggs and hatchlings are exposed to predation by gopher snakes (Pituophis catenifer sayi), green rat snakes (Senticolis triaspis), and maybe ringtails (Bassariscus astutus). In response to the presence of a predator in the area of the nest, the nesting pair of elf owls as well as 1 to 4 neighboring elf owls will cooperatively mob the predator by directing physical assaults on its head.
Known Predators:
Elf owls are the smallest owls in the world; the total length of an adult is 12.4 to 14.2 cm. Adults weigh 35 to 55 grams. Males and females resemble each other, but the total length of the female is 3% larger than the male, and the female is 6% larger in mass. Elf owls have short tails, yellow irises, conspicuous white eyebrow marks and two rows of white spots on the wings. Their backs are grayish-brown with buff mottling; cinnamon-brown blurry vertical streaks occur on the breast. Their bills are greenish yellow and their legs and feet are tan to dull yellow.
Range mass: 35 to 55 g.
Range length: 12.4 to 14.2 cm.
Sexual Dimorphism: sexes alike; female larger
Other Physical Features: endothermic ; bilateral symmetry
Average basal metabolic rate: 0.259435 W.
The maximum age of elf owls is about five years in the wild, although they can reach 14 years in captivity. Causes of mortality among elf owls include: predation, competition with other species, competition between nestlings, and exposure.
Range lifespan
Status: captivity: 14 (high) years.
Typical lifespan
Status: wild: 5 (high) years.
Elf owls live in a wide variety of habitats, including upland deserts, subtropical thorn woodlands, montane evergreen woodlands and canyon riparian forests, as well as in partially urbanized areas. Elf owls nest in old woodpecker holes in columnar cacti, such as the saguaro (Carnegiea gigantea), trees, such as the Arizona sycamore (Platanus wrightii) and agave and yucca flowering stalks. Sometimes they nest in deciduous foliage. The alligator juniper (Juniperus deppeana) is commonly used for nest cavities in canyon riparian and evergreen woodlands. In suburbs and agricultural areas bordered by woods they use fence posts, utility poles and nest-boxes.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: desert or dune ; forest ; scrub forest ; mountains
Other Habitat Features: urban ; suburban ; agricultural
Elf owls are often found in the upland deserts of Arizona and Sonora, Mexico, their range also spreads into parts of California, New Mexico and Texas. Most are members of three populations that breed in the area of the United States-Mexico border and spend the winter in southern Mexico. Three other distinct populations exist in southern Baja California and Puebla, Mexico; these populations are nonmigratory.
Biogeographic Regions: nearctic (Native )
Elf owls eat insects and small mammals and are eaten by larger raptors and snakes. While they have an important place in the food chain, they are not keystone or indicator species.
Elf owls may have a symbiotic relationship with both blind snakes (Leptotyphlops dulcis and Leptotyphlops humilis) and tree ants (genus Crematogaster). Blind snakes put in the nest to feed the nestlings may occasionally escape, remain in the nest debris, and consume ants and fly maggots that eat part of the food caches meant for the nestlings. Tree ants are symbiotic with whiskered screech-owls, and they may have a similar relationship with elf owls, in which they attack intruders but leave the owls alone.
Mutualist Species:
We do not have information on economic importance for humans for this species at this time.
There are no known adverse affects of elf owls on humans.
At hatching, Elf Owls are covered with thick white down to the base of the claws and have large feet and bare heel pads. In 5-6 days their eyes open. Within 9-12 days they can observe, sit up, snap their beaks and rear back. After 21-22 days, the Elf Owl is active and might try ineffectively to fly. Fledging occurs 28-33 days after hatching. To incite them to leave the nest, parents may refuse to bring food to the nest cavity. Fledglings are adult size and can fly weakly upon leaving the nest. Parents continue to feed the fledglings for an unknown period of time, although the fledglings are able to catch crickets by themselves almost directly after fledging. About four months after hatching, juveniles molt to resemble adults (Henry 1999; Ligon 1968a).
Elf owls are classified as endangered in California. In some areas where deforestation is occurring, elf owls face losses of breeding habitat due to the destruction of the woodpecker holes they use as nest cavities. Attempts at conservation have generally been unsuccessful up to this point. For example, a 1983 endeavor to bring back native riparian woodland along the Lower Colorado River had mixed results because the salinity content of the soil was too high and irrigation of the native trees proved difficult. Another attempt at conservation occurred in 1994 at the Black Gap Wildlife Management Area in Trans-Pecos, Texas. Nest-boxes modeled after disappearing ladder-backed woodpecker holes were set up. The effectiveness of the attempt is unknown because no studies were conducted before the nest-boxes were set up, and there were no control groups. Conservation efforts that should continue include: field experiments that assess the habitat and populations of elf owls before the introduction of nest-boxes, the result of introducing nest-boxes into the elf owl’s habitat, and a continuous censusing of elf owl populations, which are subject to natural cycles of population increases and declines.
Elf owls are protected under the US MBTA and are listed under Appendix II by CITES, but are not listed by the IUCN or US ESA.
US Migratory Bird Act: protected
US Federal List: no special status
CITES: appendix ii
IUCN Red List of Threatened Species: least concern
Hungry nestlings peep or squeak softly, twitter, and rasp at a rate of up to 48 times a minute. The rate and volume of their vocalizations indicate how hungry they are. They trill at high pitches when fed. Males have a song type that both claims their territory and advertises themselves to females. Males sing a variant of that song that includes more notes and rises and falls in volume. The male sings continuously from a possible nest cavity. As a female nears, the male goes into the nest cavity while still singing. This advertises the potential nest cavity and incites the female to accept it. Males also have distinct songs for use in flight and before copulation. Females make unique sounds during copulation and when being fed by males. Both sexes make a short, single, soft whistle to communicate during nesting, typically when the pair is feeding their young. This strengthens the pair bond. Elf owls bark as they face intruders or mob predators. In such a situation, they flip their tails quickly back and forth. Elf owls also clap their bills during threatening situations.
Communication Channels: visual ; acoustic
Perception Channels: visual ; tactile ; acoustic ; chemical
Elf owls struggle to regulate their body temperatures when humidity is low. As the temperature of the surrounding environment increases, elf owls cease activity, compress their feathers, hold their wings away from their bodies, close their eyes and start panting. They also practice gular fluttering. Because elf owls have difficulty keeping cool, it has been suggested that the desert is a secondary habitat for them. Desert vegetation arrived in the Sonoran Region around 8,000 ago. Elf owls probably originally inhabited evergreen woodlands and riparian forests in the area where the Sonoran Desert is now located.
Elf owls are usually monogamous. They may be serially monogamous (pairs remain together for the length of a breeding season but may choose a new mate for the next breeding season) or remain with the same mate for life.
Males are polyterritorial; they defend more than one nest cavity. The alternative cavities are places of roosting or of renesting if the first nest fails. The location of a roosting site seems to be based on behavioral thermoregulation.
Mating System: monogamous
Elf owls breed annually from April to July. Females begin breeding their first year following hatching. Elf owls raise only a single brood per year, but they do replace lost clutches and may replace lost broods. Clutches usually contain three eggs, but clutch size ranges from one to five eggs. Clutches in deserts are larger than in other habitats, probably because nesting begins earlier in deserts since food is more abundant early in the season in warmer, lower-elevation areas. Young fledge 28 to 33 days after hatching.
Breeding interval: Elf owls breed once yearly.
Breeding season: April to July
Range eggs per season: 1 to 5.
Range fledging age: 28 to 33 days.
Average age at sexual or reproductive maturity (female): 1 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); oviparous
Average time to hatching: 24 days.
Average eggs per season: 2.
The male captures the majority of the food for the altricial young. Often he will give the food to the female, and she will feed the chicks. After the nestlings are 2 to 3 weeks old, the female also helps to collect food.
Parental Investment: no parental involvement; altricial ; pre-fertilization; pre-hatching/birth (Protecting); pre-weaning/fledging (Provisioning: Male, Female)
The elf owl (Micrathene whitneyi) is a small grayish-brown owl about the size of a sparrow found in the Southwestern United States, central Mexico, and the Baja California peninsula.[3][4] 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.[5] It is nocturnal and feeds primarily on insects.[6]
The elf owl was formally described in 1861 by the American naturalist James Graham Cooper from a specimen collected near Fort Mohave in Arizona. He coined the binomial name Athene whitneyi, choosing the specific epithet to honour the geologist Josiah Whitney.[7] The owl is now the only species placed in the genus Micrathene that was introduced in 1866 specifically for the elf owl by American ornithologist Elliott Coues.[8][9] The genus name combines the Ancient Greek mikros meaning "small" and the genus name Athene that had been introduced by Friedrich Boie in 1822.[10]
A molecular phylogenetic study of the owls published in 2019 found that the elf owl is a sister species to the South American long-whiskered owlet (Xenoglaux loweryi) that was first described in 1977.[11]
Four subspecies are recognized:[9]
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 has not been recorded since 1931 and is assumed to be extinct.[12]
The elf owl is the world's lightest owl, although the long-whiskered owlet and the Tamaulipas pygmy owl are of a similarly diminutive length.[13] It is also the world's smallest owl.[14] 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).[15] 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, when they can often be heard calling to one another in a high-pitched whinny or chuckle. These songs often consist of 5–7 notes that repeat in short duration, similar to the sound of a young puppy. [16] The distinctive vocalizations of elf owls vary according to sex, with males exhibiting a wider repertoire of complex notes as opposed to females of the same species. Males have two primary classifications of songs, each of which share similar characteristics of structure and function. Most avian observers refer to "Class A" songs to describe those that vary in length (generally 5–15 notes), and are used as both territorial proclamation and to herald the arrival of males to females in the area. While Class A tones reflect changes in environmental factors — wind, precipitation, moonlight, and temperature — Class B songs have significantly less variation among individuals. Class B functions as the primary mating call, stimulating females and encouraging them to accept male sexual advances. As the season goes on and mating begins, Class A songs are observed with lower frequency than Class B. There are also a handful of locational, so-called "scolding", and territorial songs belonging to both male and female birds of the elf owl species. [17]
The elf owl is known to migrate in large groups, with patterns of migration varying depending on flock and habitat location. Some broods of elf owl migrate 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.[18]
Elf owls feign death when handled, an adaption that encourages a predator to relax its grip so that the owl can escape. Elf owls are also notoriously territorial. Territories are established by the male and are defended by both the male and the female, and males also tend to view their chosen female mate as a territory to be defended, as well.[17] This defense is often accomplished 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.
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 elf owls primarily use natural structures for their nesting, they have been known to nest in man-made structures such as telephone poles in urban areas. As populations decrease due to encroachment by urbanization, this may serve elf owls well (for more, see Conservation status). [19]
They generally mate for periods of three months, with male and female birds remaining in close proximity. During this time, females engage in the singing of locational calls (see Description for more information on elf owl vocalizations), and males respond with mating rituals of their own. Males and female forage independently during this time, but the male elf owl will often hunt for the female as she remains in the pairs' chosen habitat for the mating season. [20]
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 24 days before the chicks hatch.[20] 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.
After the young hatch, the female elf owl watches over them in the nesting cavity while the male often hunts for the young and the female herself. The male elf owl does most of the caretaking himself, feeding his brood independent of the female, who resides in the cavity. Generally this period of communal rearing lasts until the brood is 17 to 21 days of age.[20]
Elf owls live 3 to 6 years; in captivity they may live up to 10 years.[21] The most common types of mortality for these owls are predation, exposure, and inter-species as well as intra-species competition.[22]
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 feed mainly on arthropods such as moths, crickets, scorpions, centipedes, and beetles. 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 will also feed on small mammals (such as kangaroo rats), reptiles (spiny lizards, earless lizards and blind snakes) and birds, on occasion.[23][24]
Populations of elf owls have continued to decline in recent years due to a continued loss of native habitats, particularly those in the desert areas of California.[25] Human activities, like increasing water diversion and home construction, have decimated these desert and riparian areas, as well as increasingly abundant invasive species (such as the salt cedar). The destruction of habitat leaves many elf owls unable to nest, hunt, and reproduce in areas like California, Arizona, and elsewhere.[25]
To date, elf owls are not considered a globally threatened species, yet they are listed as "endangered" in California due to a population of fewer than 150,000 individual owls in the United States. California has implemented a captive breeding program in an attempt to increase this number, while numerous environmental and government agencies work to preserve their riparian and desert homes.[26] Some sources report that the elf owl has already been nearly eliminated in California.[27]
An elf owl named Gylfie is a major character in the Guardians of Ga'Hoole book series by Kathryn Lasky, and the 2010 film adaptation. An elf owl plays a major role in the technothriller The Elf Owl and Imagined Amenities, by Sam Biondo.
{{cite book}}: CS1 maint: multiple names: authors list (link) {{cite book}}: Check |url= value (help) The elf owl (Micrathene whitneyi) is a small grayish-brown owl 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.
