Elf owls, with the scientific name Micrathene whitneyi, are the smallest owl species in North America. They are found across the southwestern United States and Mexico. Their preferred habitat is the Sonoran Desert, known for its iconic saguaro cacti. So do elf owls make their homes in the holes and cavities of these towering cacti? Let’s take a closer look.
Quick Facts About Elf Owls
Here are some key facts about elf owls:
- They are extremely small, only about 5-6 inches tall.
- Their wingspan is around 12 inches.
- They weigh just over 1 ounce.
- Elf owls are grayish-brown in color with white speckling on the wings and back.
- They have yellow eyes and lack ear tufts.
- Their call is a series of short whistles.
- Elf owls are nocturnal and sleep in cavities during the day.
- Their diet consists of insects, small reptiles, and spiders.
- The breeding season is from March to July with a clutch size of 2-5 eggs.
- Elf owls have an average lifespan of 6 years in the wild.
An Overview of Saguaro Cacti
The saguaro cactus (Carnegiea gigantea) is an iconic symbol of the Sonoran Desert. Here are some key facts about these enormous cacti:
- Saguaros can grow over 40 feet tall and weigh up to 4,000 pounds.
- It takes about 10-15 years for a saguaro to grow its first arm.
- Saguaros can live 150-200 years.
- Their white flowers bloom at night and are pollinated by bats.
- The red fruit of the saguaro provide food for desert animals.
- Saguaros have an extensive shallow root system to collect water.
- Their trunks and arms have accordion-like pleats that expand to store water.
- Saguaros provide shelter and nesting sites for birds in their holes and cavities.
Do Elf Owls Nest in Saguaro Cacti?
Yes, elf owls do make their nests inside holes and cavities found in saguaro cacti. Here’s why:
- The holes and cavities provide a protected nesting area that keeps the owls safe from predators and sheltered from the elements.
- Cavities located high up on the arms of saguaros give elf owls an ideal vantage point for spotting insects and small prey at night.
- The cacti help regulate the temperature inside the cavity, keeping it cool during the hot desert daytime.
- Saguaros provide a stable structure for the owls to build their nests in.
- Elf owls can reuse the same nesting cavities in saguaros for many years.
In addition to saguaro cavities, elf owls have also been known to nest in holes in other large cacti, trees, and crevices in rocks. However, the saguaro appears to be their preferred nesting site.
Ideal Cavity Traits for Nesting
Not all saguaro cavities are equally suited for elf owls. The owls prefer cavities with the following traits:
- Cavity openings about 3 inches wide – large enough for the tiny owls to enter.
- Interior height of at least 6 inches to accommodate the small birds.
- Cavities located 15-30 feet off the ground for protection from predators.
- Holes facing east to avoid hot afternoon sun and get morning sunlight.
- Smooth, debris-free floor for nest building.
Elf Owl Nesting Behavior
Here are some key facts about elf owls’ nesting habits in saguaro cavities:
- Breeding pairs work together to build nests of grasses, feathers, and debris.
- The female lays 2-5 eggs over the course of several days.
- The female incubates the eggs while the male brings food.
- After 3-4 weeks, the eggs hatch asynchronously over several days.
- Both parents feed and care for the owlets as they grow.
- Young owls fledge the nest at around 4-5 weeks old.
- The parents continue to care for fledglings for a few more weeks.
- Elf owls may reuse the same nest for consecutive years.
The saguaro provides excellent nesting conditions for these tiny cavity nesters to safely raise their young.
Do Other Birds Use Saguaros for Nesting?
Elf owls are not the only bird species that utilize the cavities and holes in saguaro cacti for nesting and shelter. Some other birds that nest in saguaros include:
Gila Woodpeckers
- Cavity nesters that drill holes into cacti.
- Main creator of nest holes used by elf owls.
- Nest in early spring, allowing reuse by owls.
- Also nest in cottonwood and mesquite trees.
Gilded Flickers
- Cavity-nesting woodpecker related to Gila woodpecker.
- Require larger cavities to accommodate size.
- Often take over nest holes excavated by other birds.
- Also nest in sycamores, willows, and oak trees.
American Kestrels
- Small falcons that nest in abandoned woodpecker cavities.
- Don’t build their own nests but reuse old ones.
- Lay clutches of 3-7 eggs.
- Also use cavities in trees, buildings, and rock crevices.
Cactus Wrens
- Energetic birds that build stick nests in protected cavities.
- Use thorns and fibers as building materials.
- Nests provide shelter from sun and concealment.
- Also nest in brush, trees, and rock crevices.
Purple Martins
- The largest North American swallow.
- Nest colonially in abandoned woodpecker holes.
- Use mud to partition and shield nest cavity.
- Also nest in artificial boxes and gourds.
In addition to birds, some small mammals like squirrels and woodrats may also use saguaro cavities for dens. Overall, the giant cacti provide valuable nesting real estate for a diversity of desert creatures.
Threats Facing Saguaros and Elf Owls
Both saguaro cacti and elf owls face a number of threats to their survival in the Sonoran Desert, including:
Saguaros
- Habitat loss due to development and agriculture.
- Climate change altering weather patterns.
- Collection by humans.
- Vandalism and gunshot wounds.
- Invasive non-native plants.
- Fungal diseases like saguaro rust.
Elf Owls
- Loss of nesting cavities in saguaros.
- Predation by expanding raven populations.
- Habitat loss and fragmentation.
- Collisions with buildings and vehicles.
- Pesticides reducing insect prey populations.
- Light pollution disrupting nocturnal behaviors.
Protecting remaining stands of mature saguaro cactus and designating wilderness areas will be key conservation strategies to protect both the iconic cacti and the diminutive owl that depends on it.
Conclusion
In conclusion, elf owls do indeed make their nests inside cavities and holes in the giant saguaro cacti found in the Sonoran Desert. The saguaro provides the ideal nesting site for these tiny owls, giving them shelter from predators, insulation from harsh desert conditions, and a stable structure for raising their young. Elf owls have a strong affinity for saguaros, but also make use of nest holes in other cacti, trees, and rock crevices. A diversity of other desert birds join elf owls in utilizing the cavities within saguaros for their own nesting needs. Unfortunately, both elf owls and saguaros face threats from human activities and climate change. Protecting remaining populations of saguaros will be key to conserving the habitat of the diminutive elf owl.