Athene cunicularia (Molina, 1782)
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Athene cunicularia, Speotyto cunicularia
Basis for Listing
The burrowing owl is primarily a western species, breeding in parts of Mexico and throughout the western half of the United States (excluding the humid Pacific Northwest) into the southern Canadian Prairie Provinces. In Minnesota, the species once bred throughout the western prairie margin from Jackson County to Marshall County. It was considered a regular breeder in other prairie regions in the first half of this century until the population began to decline dramatically.
The burrowing owl is a small, 23-29 cm (9-11 in.) high, light brown owl whose most distinctive features include its long legs, short tail, and lack of ear tufts. It is most often seen perched on the ground or atop a small raised mound or fencepost. The species bobs up and down when agitated and will usually dive into its burrow rather than take flight when approached too closely.
Burrowing owls select open, grazed pastures or native, mixed-grass prairies populated by burrowing mammals. In Minnesota, American badgers and Richardson's ground squirrels (Spermophilus richardsonii) are thought to be the primary nest excavators. In much of the burrowing owl's range in the western United States, prairie dog (Cynomys spp.) towns are commonly occupied as breeding areas. Areas of intensive agricultural use are usually avoided.
Biology / Life History
Little is known about the migratory habits of the burrowing owl, but the northern population segment is believed to overwinter in Texas. Burrowing owls in the Florida population may excavate their own burrows, but everywhere else they use abandoned burrows of small mammals, which may require enlargement by badgers before becoming suitable for burrowing owl inhabitation (Haug et al. 1993). Clutches average about 6-8 eggs. The female incubates the eggs and remains in the nesting burrow with the owlets for up to two weeks after hatching. During this time, the male hunts and brings food to the female, who tears it up and feeds it to the young. Owlets leave the nest after about 44 days. They learn to hunt by observing their parents and practicing prey capture on small objects, injured insects, and siblings. Burrowing owls may form loose colonies, with several pairs nesting in the same burrow system. Home ranges for most individuals are less than 100 ha (247 ac.). Burrowing owls are opportunistic feeders and will eat whatever prey they can catch. This includes mainly arthropods, but small mammals, birds, amphibians, and reptiles may also be eaten. Burrowing owls hunt by hopping along the ground or observing from a perch, primarily at dawn and dusk (Haug et al. 1993).
Conservation / Management
Preservation of short-grass habitat, particularly large pastures with Richardson's ground squirrel colonies, is important. Grazing or burning may be necessary to maintain the suitability of this habitat for the burrowing owl (Haug et al. 1993). Sites where owls have nested in the recent past should be monitored for breeding activity. Providing burrowing owls with artificial burrows may be necessary in short-grass areas that do not support burrowing mammal populations. Any future reintroduction efforts may require control of predators, particularly great horned owls (Bubo virginianus), at release sites in order to increase survival of burrowing owls (Martell 1990). A 600-m (1,968-ft.) radius around nest burrows should be protected from pesticide application (Haug and Oliphant 1990). Many burrowing owls are killed on roads, as they often sit on fence posts or on the roads themselves while hunting. Installation of perches for hunting and predator detection may help reduce road-kills (Haug et al. 1993). In the past, posters, mailings, and other media have been successful in obtaining information about burrowing owls and could be employed at regular intervals in the future. It is important to educate landowners to ensure their cooperation in conserving burrowing owls and owl habitat.
Conservation Efforts in Minnesota
A reintroduction effort began in Minnesota in 1985, with the release of four captive-bred burrowing owls in Rock County. In 1986, the Minnesota Department of Natural Resources, the Raptor Center, and the University of Minnesota joined forces to develop survey and management strategies for recovery of the burrowing owl (Martell 1990). Sightings of burrowing owls were solicited from the public beginning in 1986. From 1988 to 1990, posters were distributed throughout western Minnesota to solicit nesting reports. During 1988-89, road surveys were conducted in the historic range of the species. Between 1986 and 1990, 105 juvenile burrowing owls were released (Martell 1990). However, none of the released birds have been sighted in subsequent years and no band returns have been received. Due to the lack of success, further large-scale reintroductions cannot be justified (Martell 1990). The Minnesota Biological Survey continues to target this species as surveys are completed in the prairie region of the state. Burrowing owls were observed in western Minnesota in 1999, 2002, and 2004-2007. Nesting was confirmed in Norman County in 2006 and in Polk and Pipestone counties in 2007. These records represent the first documented nesting of burrowing owls in Minnesota since 1990.