THE BURROWING OWL
by Eileen Dowd Stukel
Originally published in the July/August 1994 edition of the SD Conservation Digest.
Picture an owl in your mind's eye. Chances are you're thinking of a large, bulky bird with huge eyes huddled furtively in a tree. Think again, this time of a small, long-legged owl of open country, readily seen during the day--the burrowing owl.
The burrowing owl's scientific name (Athene cunicularia) and its many nicknames leave little doubt about its lifestyle. Athene was a Greek goddess of wisdom, and cunicularia means burrower. Nicknames include prairie dog owl, gopher owl, ground owl, and howdy owl.
This 8-inch-tall raptor is found throughout much of the western United States, portions of southcentral Canada, and much of Central and South America, excluding the jungles of the Amazon. Burrowing owls nest in vacant burrows excavated by prairie dogs, badgers, Richardson's ground squirrels, and even tortoises of the Southwest. This adaptation has served burrowing owls well, since burrows not only furnish nest sites, but also escape from predators and temperature extremes. Burrowing owls nesting in the northern portions of their range migrate south for the winter, while birds in the southern range and Florida are year-round residents.
Burrowing owls return to South Dakota alone or in pairs in April or early May. Observations of banded birds have shown that they do not mate for life, but a male will frequently defend and use the same burrow for more than one year, as long as the burrow has not collapsed or been destroyed.
A male owl shows off the white feathers of his throat and eyebrows during a bowing display, while he repeatedly calls "cu-coo" to attract a mate. Once a pair is bonded for the season, they begin converting an abandoned burrow into a nesting chamber for their clutch of 3-10 eggs. The pair may enlarge a burrow by digging with their claws, or less typically by digging with their bills or by walking through with wings extended to scape dirt from tunnel sides. Favored burrows may slope gradually away from the entrance and have a sharp turn, which keeps the enlarged nesting chamber dark.
Next the pair displays an extremely unique characteristic. They line the entire nesting burrow and entrance with dried animal dung, preferably from cows or horses. Many believe this custom serves to mask the scent of the owls and owlets to protect them from predators. In experiments where researchers removed the dung lining, the owls replaced the stolen material within a day.
Only the female burrowing owl has a brood patch, evidence that she alone incubates the eggs for approximately 3 weeks. She appears at the burrow entrance begging to be fed by her mate. He may be perched on a nearby fencepost or busily capturing mice, snakes, locusts, crickets, beetles, lizards or small birds, ground squirrels, prairie dogs, or cottontails. Each adult eats more than its 5-6 ounce weight each day.
Only two weeks after hatching, the grayish-white chicks begin appearing at the burrow entrance. To meet the increasing food demands of a typical brood of 3-6 chicks, now both the mother and father forage by hovering over prey, low-level aerial chases, capturing prey on foot, or darting from perches after flying insects. The adult male is the main nest defender, but neighboring pairs share foraging areas.
Among North American owls, only the barn owl can rival the vocal variety of the burrowing owl, which produces at least 17 different sounds. The dangers of living in a barren landscape with many potential ground and aerial predators can be offset with clear and specific communication, seen in both prairie dogs and burrowing owls. Even young burrowing owls use at least 3 different sounds. One call imitates a rattlesnake's rattle, an obvious survival strategy in an ecosystem where rattlers may be common residents.
Before fledging at about 6 weeks of age, young owls accompany parents on foraging trips. By late summer, both young and adult owls disperse from their nesting colonies. Burrowing owls banded in South Dakota have been relocated in at least 6 states, the most southern and presumed wintering areas being Texas and Oklahoma. At least a few birds winter in the state, because this species has been documented in Pennington, Brown, and Clay counties during various winters.
Fewer and fewer burrowing owls return to their nesting colonies each year. This species has greatly declined in Canada and is considered endangered in our neighboring states of Minnesota and Iowa. The burrowing owl is of "special concern" in several states, including South Dakota, North Dakota, Wyoming, and Montana. Conversion of prairie habitat for other uses, loss of nesting habitat from poisoning of prairie dogs and ground squirrels, poisoning of burrowing owls through methods that are not specific to rodents or predators, and accidental and intentional shooting have all contributed to the burrowing owl's decline.
This unique and beneficial creature need not go the way of the black-footed ferret, an animal that declined almost to extinction before we took meaningful action. The ferret, swift fox, and burrowing owl comprise only a fraction of the species that are partially or completely dependent on the prairie dog ecosystem. The burrowing owl can be conserved and restored with a change of attitude about the importance and complexity of this ecosystem. Please report any sightings of burrowing owl nesting colonies to the South Dakota Natural Heritage Program and help this resilient and interesting prairie bird endure for future South Dakotans to enjoy and value.