The elf owl (Micrathene whitneyi) is a small species of owl that is native to the southwestern United States and Mexico. Measuring only about 5-6 inches tall, elf owls are the smallest owls in North America. They have a fascinating and unique life cycle that is intricately tied to the life cycle of the saguaro cactus.
What does an elf owl look like?
Elf owls are tiny owls with large heads and no ear tufts. Their plumage is grayish-brown above and whitish below with white spotting. They have long legs with feathering down to the toes and a short tail. Their facial disks are pale gray. Compared to other owls, elf owls have very small bills and large eyes, likely an adaptation to being active at dusk and dawn.
Male and female elf owls look alike. Juveniles have less white spotting below and more buffy edges to the wing and tail feathers. Elf owls weigh only 1.5 to 2 ounces as adults.
Where do elf owls live?
Elf owls are residents of the Sonoran and Chihuahuan Desert regions in the southwestern United States (California, Arizona, New Mexico, Texas) and Mexico. Their range extends south to central Mexico.
Within their desert habitat range, elf owls are typically found in areas with saguaros and cottonwoods, as these provide cavities for nesting and roosting. They avoid higher altitude and grassland areas. Elf owls are well-adapted to arid environments, getting most of their water needs from prey.
What is the elf owl’s habitat?
Elf owls occupy desert scrub habitat characterized by stands of giant saguaro cacti and riparian corridors with cottonwoods and willows. They rely on the saguaro for nesting cavities and are rarely found far from saguaro cactus forests.
Typical elf owl habitat contains components such as:
- Saguaro cacti – Provides cavities for nesting and roosting
- Cottonwoods – Also supplies cavities
- Mesquite, palo verde, ironwood – For foraging
- Cholla, prickly pear, barrel cacti – Provides cover
Elf owls frequent desert scrublands with fairly dense vegetation. They avoid open or rocky areas. In some parts of their range, elf owls occupy riparian woodlands along desert rivers and streams.
What does the elf owl eat?
Elf owls are small predators that hunt mainly insects, spiders, scorpions, centipedes, small lizards, and occasionally small rodents. They are agile, acrobatic hunters that can glean prey items from vegetation as well as capture them on the wing.
Typical elf owl prey includes:
- Moths
- Beetles
- Crickets
- Grasshoppers
- Caterpillars
- Cicadas
Elf owls are primarily nocturnal or crepuscular hunters, but can occasionally be seen foraging during the day, especially at dawn and dusk hours. At night, they typically hunt from perches 3-10 feet above ground, dropping down on prey detected by sound. Their diet varies seasonally based on prey availability.
When is the elf owl breeding season?
Elf owls begin their breeding season in late winter or early spring. Courtship activities increase through March and April. The exact timing can vary based on geographic location.
In Arizona, egg laying typically begins in mid-April. Further south, elf owls breed earlier. In Mexico, breeding activities may start as early as late February.
Elf owl breeding season reaches its peak from May to June across most of the range. The last active nests are usually seen in early July. Most breeding activities subside by late summer.
How does the elf owl attract a mate?
During breeding season, male elf owls use a primary song to advertise their territory and attract a mate. Their song is a rapid series of short, whistled notes described as a “bouncing-ball” call.
Male elf owls may also perform courtship flights at dusk involving spiraling flight displays up to 200 feet in the air above their territory. They give their primary song during these flights.
In addition to vocalizations, mutual preening helps strengthen the pair bond between male and female elf owls once they form a pairing. Like other owls, elf owls do not build nests. They rely on natural cavities for nesting.
Where does the elf owl nest?
Elf owls are cavity nesters that nest almost exclusively in holes excavated by woodpeckers in saguaro cacti. The nest cavity is usually 10-30 feet above ground in the arms or trunk of a saguaro.
Ideal elf owl nest sites include:
- Old woodpecker holes in living or dead saguaros
- Natural cavities in cottonwoods
- Cavities in tall, old willow trees
- Wooden nest boxes put up specifically for birds
The elf owl’s dependence on the saguaro cactus makes it a keystone species of the Sonoran Desert ecosystem. Outside of the range of the saguaro, elf owls are very limited in their breeding.
How many eggs does the elf owl lay?
A typical elf owl clutch contains 2-3 eggs. The female elf owl lays one egg every 1-2 days over a period of a few days until the clutch is complete.
Elf owl eggs are small and elliptical. They are creamy white and measure about 1.14 x 0.89 inches. The eggs are incubated by the female only.
In years with abundant prey, elf owls may produce two or even three clutches in a season. Second clutches are usually smaller with only 1-2 eggs laid.
How long does it take elf owl eggs to hatch?
Elf owl eggs hatch after an incubation period of 18-21 days. Only the female incubates the eggs, while the male provides food for her.
The eggs generally all hatch within 24-36 hours of each other. Hatching is asynchronous because the eggs are laid 1-2 days apart. Newly hatched elf owlets weigh only 4-6 grams, less than the weight of a nickel.
How do elf owl parents care for their young?
Elf owl parents provide extensive care for their offspring from hatching through fledging:
- The female broods the hatchlings to keep them warm for the first 7-10 days.
- Both parents defend the nest cavity aggressively against predators.
- The male passes food to the female, which she tears into small pieces to feed the owlets.
- Parents continue to provision the owlets for 3-4 weeks until they fledge.
- Fledged young are fed by the parents for another 2-3 weeks as they learn to hunt.
Elf owlets grow rapidly and are able to leave the nest cavity at around 20-24 days old. They can fly competently by about 4 weeks of age.
What are the risks to elf owl eggs and chicks?
Elf owl eggs and chicks face threats from a few key predators:
- Rat snakes – A major predator able to access nest cavities
- Coyotes
- Bobcats
- Ringtails
- Raccoons
Elf owl parents actively defend their nest, mobbing and dive-bombing intruders. But rat snakes are adept at raiding nests and remain a primary danger. Nest loss to predators may approach 50% in some populations.
How long do elf owls live?
In the wild, elf owls typically live around 5-6 years. The oldest known wild elf owl was over 11 years old when recaptured and rereleased during banding studies.
In captivity, elf owls have lived up to 14 years under human care. However, average lifespan is lower in captive individuals than wild owls.
Major causes of mortality for wild elf owls include predation, starvation, disease, and harsh weather. Vehicles and flying into windows also contribute to elf owl deaths, especially among young owls.
What are the elf owl’s enemies?
As a tiny owl, the elf owl faces predation threats from a variety of desert predators, including:
- Coyotes
- Bobcats
- Ringtails
- Foxes
- Raccoons
- Rat snakes – A major nest predator
- Raptors – Hawks, falcons, and owls will prey on elf owls
- Feral cats
Vehicles and flying into windows also kill many elf owls each year. Elf owls may mob larger owls who compete for their cavities, occasionally resulting in their death.
What time of day is the elf owl active?
Elf owls are primarily crepuscular and nocturnal. This means they are most actively hunting around dawn and dusk, and at night.
During daylight hours, elf owls roost in cavities, remaining inactive and hidden. Their large eyes and excellent night vision allow them to locate and capture prey after dark.
Elf owls may occasionally forage during the day, especially early and late when the sun is low. But the majority of their activity occurs at night when risks from diurnal desert predators are lowest.
In hot desert environments, being nocturnal also conserves water and keeps elf owls cooler. Their biological clock is naturally attuned to the rhythms of nighttime activity and daytime rest.
Is the elf owl endangered?
No, elf owls have a large range and relatively stable population numbers. They are classified as Least Concern on the IUCN Red List. Their numbers can fluctuate locally based on habitat and prey availability.
However, elf owls do face some conservation threats:
- Habitat loss in riparian areas
- Urbanization reducing saguaros
- Saguaros dying off from drought
- Pesticides reducing insect prey populations
- Vehicle collisions and window strikes
Ongoing conservation efforts focus on creating and preserving public lands protecting Sonoran Desert habitat. Providing artificial nest boxes also helps offset cavity losses. Elf owls readily accept nest boxes.
What is unique about the elf owl?
Some fascinating traits make the elf owl unique among owls:
- Smallest owl: Weighing 1.5-2 ounces, elf owls are the lightest owl in the world.
- Saguaro dependence: Elf owls rely almost solely on saguaro cacti for nesting cavities.
- Territorial: Despite their size, elf owls aggressively defend their territory.
- Insectivorous: A highly insectivorous diet compared to most owls.
- Cryptic: Excellent camouflage helps them disappear into the desert environment.
The elf owl fills a unique ecological niche as a small, highly specialized desert predator.
Conclusion
In summary, elf owls have a fascinating life cycle tuned to the seasonal cycles of the Sonoran Desert. Their breeding activities peak in spring and early summer. Elf owls are cavity nesters, relying heavily on saguaro cacti for nest sites. Parents provide extensive biparental care until the young fledge. Though small, elf owls are fierce defenders of their nest and territory.
Elf owls are uniquely adapted to the desert where they form an important part of the ecosystem both as predators and as prey. Conservation of their fragile desert habitat remains crucial to preserving elf owl populations into the future.