Owls are known for being nocturnal birds of prey, excellent hunters with a range of adaptations that aid their hunting and survival. However, contrary to popular belief, not all owls are strictly nocturnal or live in trees or forests. There is one very unique species of owl that lives primarily underground – the burrowing owl!
The Burrowing Owl
The burrowing owl (Athene cunicularia) is a small, long-legged owl found throughout open landscapes of North and South America. As their name suggests, burrowing owls nest and roost in underground burrows, often those dug by prairie dogs, ground squirrels, and other small mammals. This makes them unique among owls as most other owl species nest and roost in trees, cliffs, caves, or crevices.
Some key facts about the burrowing owl:
- Length: 7.5-11 inches
- Wingspan: 21-24 inches
- Weight: 4.5-8 ounces
- Lifespan: Up to 9 years in wild, over 10 years in captivity
- Diet: Insects, small mammals, reptiles, amphibians
- Habitat: Grasslands, prairies, agricultural areas, deserts
- Range: Western and central North America, Florida, Mexico, Central and South America
- Conservation status: Least concern but declining in parts of range
The burrowing owl gets its name from its unique habit of nesting and roosting in underground burrows. They prefer burrows dug by ground squirrels, prairie dogs, badgers, foxes, and coyotes, but may dig their own if no suitable burrows are available. Living underground provides shelter and protection.
Adaptations for Underground Living
The burrowing owl has several key adaptations that allow it to thrive underground:
- Long legs: Their long legs allow them to swiftly run across open ground and quickly dive into a burrow when danger approaches.
- Compact size: Weighing only 4-8 ounces, their small size lets them easily maneuver through burrows.
- Feathers: Their cryptic brown and beige barred and spotted plumage provides camouflage in open dry environments.
- Eyes: They have bright yellow eyes and excellent vision adapted for hunting in low light underground.
- Hearing: Asymmetrical ear placement allows them to precisely locate prey by sound.
- Burrow maintenance: They keep their burrows clean and maintain the entrance to monitor for predators.
Hunting and Feeding
Despite living underground, burrowing owls emerge at dawn and dusk to hunt. They perch on posts or mound entrances, scanning for prey across open ground. When prey is spotted, they swiftly fly or run along the ground to catch it.
Their diet consists mainly of large insects like grasshoppers, beetles, and moths. They also prey on small mammals like voles, pocket mice, and kangaroo rats, as well as small birds, reptiles, and amphibians. They may catch several prey items during each hunting session.
After catching prey, they carry it back to their burrow to eat. They swallow small items whole and tear larger prey into pieces with their beak and feet. Indigestible parts like fur, bones, and exoskeletons are compacted into pellets and later regurgitated.
Breeding and Nesting
Burrowing owls form monogamous breeding pairs during the spring breeding season. The breeding season runs from March to August, varying somewhat across their range. The male calls from a burrow entrance or mound to attract a female.
Once paired, the female lays a clutch of 6-12 white eggs within an underground nesting chamber lined with grasses, feathers, and mammal dung. She incubates the eggs for 3-4 weeks while the male provides food. The chicks hatch with closed eyes and remain in the nest chamber for 2-3 weeks, cared for by both parents.
At around 3 weeks old, the chicks emerge from the burrow and perch at the entrance as adults provide food. They learn to hunt starting at 4 weeks old and fledge at around 6 weeks, though the parents continue to provide some food for a couple more weeks as they hone their skills.
Threats and Conservation
Though still widespread, burrowing owl populations have declined significantly in parts of their range. Habitat loss from urbanization and agricultural expansion is a major threat, as they require open native grasslands and prairies with abundant mammal burrows.
Other threats include:
- Vehicle collisions in areas near roads
- Control of burrowing mammals like prairie dogs, eliminating nesting sites
- Pesticides reducing prey availability
- Climate change and drought
Conservation efforts focus on protecting intact grassland habitat, managing agricultural lands to support owls, installing artificial nest boxes where burrows are lacking, and public education campaigns. Continued habitat loss could worsen declines, but well-planned conservation measures can secure the future of this unique burrowing owl.
Conclusion
The burrowing owl is the only owl uniquely adapted to nesting and living underground, inhabiting burrows dug by small prairie mammals. Long legs, cryptic feathers, small size, keen hunting skills, and tolerance of low light allow them to thrive. They play an important role controlling insect and small mammal populations in prairie ecosystems. Ongoing conservation efforts focused on habitat protection and management will help ensure the burrowing owl continues gracing North and South American grasslands with its presence for years to come.