Species Fact Profile: Burrowing Owl (Athene cunicularia)

                                                           Burrowing Owl

                                           Athene cunicularia (Molina, 1782)

Range: Western North America (southern Canada, western United States), Central and South America.  Isolated population in Florida, as well as some of the Caribbean islands

Habitat: Open Grassland, Prairie, Desert

Diet: Insects (about 90% of their diet), such as grasshoppers and beetles.  They will also eat small mammals and birds, as well as snakes, lizards, bats, and earthworms

Social Grouping:  Colonial, becoming territorial during the breeding season

Reproduction: Monogamous (though up to one third of owlets may be produced via “affairs,” and sometimes a male will have two females).  Breed annually (can have more than one clutch per season, but not usual).  Courtship consists of singing, preening, and the presentation of food from the male to the female.  Engage in some display flights prior to breeding.  Nesting takes place in spring.  Females lay 2-12 eggs in a burrow lined with ungulate dung, which hatch after 28-30 days (the dung attracts insects, which the owls and their chicks can eat).  An egg is laid every 1-2 days, with incubation starting with the laying of the first egg.  Male hunts and provides food for himself and his mate and the chicks.  The female stays with the chicks until they can thermoregulate; once they can, she assists in hunting.  Fledge at 7-8 weeks, sexually mature at 10 months.

Lifespan: 10 Years

      Conservation Status: IUCN Least Concern, CITES Appendix II

• Males and females both weigh 125-255 grams, stand 19-25 centimeters tall, and have a wingspan of 53-61 centimeters.  The legs are long and lightly-feathered, the tail short (often a little longer in the male).  It’s been suggested that males are 3% larger than females, but with the wide weight ranges seen in adults, this finding is not likely to be significant
• Sexes alike (females may be a little darker on average, with less barring) with brown plumage, barred on the breast, with a white chin stripe and some spotting on the back.  Juveniles lack the chest barring and have less spotting. The eyes are yellow with white “eyebrows” above them.  Beaks are dark grey or yellow, varying by subspecies.  There are no ear tufts.
• Utilize burrows that are usually dug by other species, such as prairie dogs or tortoises, though the Florida owls typically dig their own burrows (which tend to be shorter than those seen elsewhere in the range).  Burrows are up to 3-4 meters long, often with a curve to prevent light from reaching the chamber at the end.  Will sometimes use other structures for shelter, such as rock cavities.  Will use pipes as artificial nests.  Sometimes put debris, such as bottle caps, at the entrance of the burrow, possibly to indicate that it is occupied
• Have a higher tolerance for carbon dioxide than many other birds, adaptation to burrowing
• Active by day (hunting at night has been observed), but most active at sunset and sunset.  Middle part of the day often spent dustbathing or preening
• Primary vocalization is a high-pitched two-note coo, used by males to establish pairs and demarcate territories.  Also have a defensive scream, a cluck, and a chatter.
• Most hunting takes place with 1.5 kilometers of the nest, but may range as far as 10 kilometers.  When hunting insects, owls often pursue their prey on the ground.  Can also hunt from perches or on the wing
• Will stash food during times of plenty, with some caches having over 200 rodents
• Eat some fruits and seeds, especially those of prickly pears and cholla cacti
• Predators include larger birds of prey (peregrine falcons, Swainson’s hawks, etc), as well as foxes, coyotes, bobcats, and badgers; reptiles may take eggs or chicks from nests
• When threatened, known to retreat from sight and make a buzzing noise, reminiscent of a rattlesnake’s rattle, apparently Batesian mimicry
• Species name from the Latin cunicularius, meaning “burrower” or “miner”
• At least 18 subspecies recognized, most of them in the Caribbean or the Andes.  At least two subspecies, the Antiguan burrowing owl A. c. amaura, and the Guadeloupe burrowing owl A. c. guadeloupensis, are now extinct.  A fossil subspecies is known from the Bahamas
• Decline of prairie dogs and other burrowing animals has led to a reduction in available nest sites, though they can be provisioned with artificial burrows.  In some cases, deforestation and conversion of habitat to pasture has provided additional habitat for the species, allowing it to expand its range in some directions
• Causes of mortality include predation from domestic dogs and cats, collision with cars, destruction of burrows, and pesticide poisoning.  Island subspecies were driven to extinction by introduced mongoose
• Captive breeding and reintroduction program underway in California, led by San Diego Zoo; previous programs in Manitoba, Minnesota, and British Colombia, with mixed results