Burrowing Owls
Last Update/Review: June 17, 2002
Status | Description | Habits | Reproduction | Food | Limiting Factors | Management and Outlook
Status
The Alberta Wildlife Act lists the burrowing owl as a threatened animal. Both the birds and their nests are fully protected.
The world distribution of burrowing owls includes the prairie regions of western Canada, the United States, Central America, and South America. Small populations are also found in Florida and the Caribbean islands. Once numerous, the species generally has declined throughout all areas. For example, burrowing owls are now absent from large parts of western North America.
Historically, Canada had good breeding populations of burrowing owls throughout the dry, short-grass prairie habitat of the four western provinces. Nests occurred in the Okanagan area of British Columbia and in an area outlined by Calgary, Wetaskiwin, and Wainwright in Alberta; Prince Alberta and Yorkton in Saskatchewan; and Winnipeg in Manitoba.
Since the 1930s, there has been a steady decrease both in the number of birds and their geographic range in the prairie provinces. They disappeared completely from British Columbia. In the late 1970s there were approximately 2100 breeding pairs left in Canada. Rough estimates suggested there might have been 1300 breeding pairs in Saskatchewan, 720 in Alberta, and 100 in Manitoba. By 1987 the population estimates decreased to 400 in Saskatchewan, 700 in Alberta and 35 in Manitoba. The 1987 Alberta population estimate was based on an extensive survey. (It is likely that the population was underestimated in 1977.) British Columbia has now established a few pairs to re-introduce burrowing owls in the Okanagan as part of a management program.
Detailed information about the Alberta population of burrowing owls is limited. Recent reports of breeding birds are restricted to an area bounded by Cardston, Calgary, Drumheller, Hanna and east to the Saskatchewan border.
For more information, check out the Status of the burrowing owl in Alberta report.
Description
Burrowing owls are comical little birds that generally look like a short fat owl on stilts. They have the typical large "owl" head and eyes, relatively large wings and a stubby tail. They often stand upright on long thin legs. By standing tall, they can see farther out over the flat prairie. Burrowing owls are coloured with a mottled pattern of dark brown and light brown spotted with white. The underparts are pale brown to white. This coloration provides good camouflage in a prairie habitat.
Burrowing owls are the only North American owl in which the female is smaller than the male. Adult females may be more heavily coloured on the underside and often, (but not always), appear darker than the male. Again, it is thought that the difference probably reflects the difference in the habits of the birds. While females spend much of their time underground, males are nearly always out in the direct sun and their colour appears to fade over the summer.
Habits
Burrowing owls do not seem to do many of the things we usually associate with owls. They live in burrows in the ground, are active during the day, and prefer to eat insects! In many populations of burrowing owls, breeding pairs live close together in colonies. They are often seen during the day "just standing around" on or near the entrance to their home burrow.
The burrow is probably the most unique feature of burrowing owls. It is important to the birds for protection, raising young, social contacts, temperature control, and attracting food. Burrowing owls rarely dig their own burrows, and in Alberta, they prefer to take over and modify abandoned burrows of badgers, ground squirrels, or foxes. Even on their wintering grounds, the owls use burrows for roosting and protection.
Adult burrowing owls will defend the area directly around their burrow. Often the male bird stands watch nearby while the female and young birds are underground. If an intruder comes near the burrow, the male sounds an alarm call and then tries to lure the animal away with a series of short distracting flights. If the female and young are above ground, the female usually runs away and helps to draw the danger away from the burrow. The adults may try a direct attack if the intruder continues. In most cases the young birds retreat to the back of the burrow and make a hissing noise which sounds remarkably like a rattlesnake. In most cases this is enough to scare any intruder!
Burrowing owls are found in Alberta only during the summer. It is not known exactly where our birds spend the winter but they probably migrate to the southwestern United States and Mexico. One young bird banded in Manitoba was found in Texas four to six weeks later.
In general, the birds return to Alberta in late April. The adults may use the same burrow as in previous years or may take over a new site. However, they usually stay in the same general area as long as it is suitable for nesting. The birds spend the entire summer at or near the burrow, seldom flying more than 1 km away. They leave for their wintering areas in September; the young may leave earlier than the adults.
Reproduction
Male and female burrowing owls do not pair for life, although some birds apparently stay together for more than one year. When the birds return in the spring, they begin an elaborate courtship display, which includes flashing white markings, cooing, bowing, scratching, nipping, stretching, and repeated short flights.
Once the pairs are determined, the male begins to modify a burrow. He may use his feet, beak, or wings to dig and scrape dirt out of the burrow. Then he lines the burrow with dried plants, feathers, and cow dung. The lining is thought to insulate the burrow and help keep it cool during the day and warm during the night. This would help incubate the eggs and keep the humidity high in the burrow. The lining also may provide some protection from predators by masking the scent of the owls.
When the nest is ready, the female lays 6 to 12 white eggs and incubates them for about four weeks. During this time, she remains underground and the male provides food for her. Incubation starts as soon as each egg is laid. Thus, the eggs hatch at different times (that is, the egg laid first will hatch first). Newly hatched young stay in the burrow until the nest gets too crowded (about two weeks). After this, they stand at the entrance to the burrow and simply wait for the adults to feed them. The young birds start to hunt for themselves seven or eight weeks after hatching.
After the young are active above ground, the owls may move to another burrow or use two or three burrows at the same time. This makes it easier to distribute food more evenly to the young, avoids crowding, and reduces the chances of a predator killing the entire group. Also the birds can avoid the parasites (mainly fleas, mites, and lice), ants, and remains of prey which accumulate in the nest burrow.
Food
Burrowing owls consume a variety of foods. They eat a tremendous number of insects (mainly grasshoppers and beetles) as well as a few mice, voles, ground squirrels, toads, and small birds. burrowing owls also eat animals that they find dead. Grasshoppers are the most common food of young birds as they learn how to hunt. Although insects make up a large part of the diet (80% to 90% of the number of things eaten), small mammals and birds supply most of the energy for burrowing owls.
In the early summer, adult birds usually hunt at dawn and dusk (crepuscular). However, at other times of the year they hunt mainly during the night (nocturnal). The owls may also be active during the day (diurnal) although they usually are not hunting.
Burrowing owls use some unique hunting techniques. They chase down grasshoppers and beetles, use their feet to catch large bugs in mid-air, or hover close to the ground before diving at their prey. They also hunt from perches such as telephone poles, fence posts, or rocks. Young birds in particular pick up dead animals on roads. They also scurry after insects drawn to the warmth of the pavement on roads at night.
Limiting Factors
Burrowing owls require open areas with low ground cover, existing burrows, and abundant food. Each of these needs are threatened in the prairie regions. The critical factor in the decline of burrowing owl populations appears to be the loss of burrows. Ground squirrels, badgers, and prairie dogs (in the United States) are considered pest animals and their numbers have been reduced in many areas. Burrowing owls rely on these species to create new burrows or maintain old ones. Without the burrowing mammals, the owls cannot find suitable nesting sites.
Loss of habitat through cultivation, resource exploration and development, expanding human settlements, and road construction continues to reduce the area available to owls. In particular, cultivation often destroys burrows and replaces the natural low vegetation with high cereal crops. Burrowing owls cannot hunt in high vegetation.
Many burrowing owls have been killed accidentally as a result of poison programs aimed at reducing the populations of pests and insects. The owls may die when they scavenge carcasses of poisoned animals. It is not known what direct effects grasshopper insecticides may have on burrowing owls. However, the birds are affected indirectly by having fewer grasshoppers to eat. This shortage may be critical for young birds.
A large number of burrowing owls are killed on roads and highways, at night and during the day. Burrowing owls often fly low and are hit when they cross a road. As indicated earlier, young birds are attracted to dead insects and ground squirrels as well as live insects on roads.
Unfortunately, burrowing owls are often shot either accidentally or on purpose. They tend to be unafraid of people and are easy to see as they stand up on their long legs in open areas or on perches. At the mouth of the burrow, owls look about the same size and colour as ground squirrels and may be shot by mistake. In Alberta it is illegal to kill or disturb burrowing owls or their nests at any time of the year.
There is also a variety of natural factors involved in limiting the number of burrowing owls. Eggs and young birds may be killed by snakes, owls, hawks, badgers, skunks, foxes, weasels, cats, and dogs. Severe late spring storms may kill the adult birds or trap the female in the burrow. Heavy rainstorms occasionally flood burrows and destroy eggs or drown young birds.
Management and Outlook
Burrowing owls are protected by wildlife legislation in all four western provinces. In addition, each province is involved in management programs aimed at gathering more information about their birds assessing the status of the species, and trying to maintain or increase the number of breeding pairs. Methods of protecting current suitable range are being investigated as well.
Alberta currently has an ongoing research program on burrowing owls. This program involves banding owls in the area of Castor and Hanna. Researchers hope to gain information about overwinter survival rates, habitat preferences, reuse of nest sites (fidelity) and migration of these birds. A three-year survey of the population number and geographic distribution throughout the province concluded in 1988. The program depended heavily on information from the public. Once we know how many birds we have and where they are, the Natural Resources Service can design management policies to ensure future protection of the species.
Burrowing owls will readily use artificial burrows. This technique could be used to help solve the problem of not enough suitable burrows being available for the owls. We know the owls will nest in plywood boxes, plastic drain pipes, or concrete pipes. These "burrows" must include a sloping entrance tunnel, a 90-degree bend, and an enlarged nesting area. The bend in the tunnel provides darkness at the nest. The "burrow" is buried at least 15 cm in the ground to allow for natural temperature and humidity conditions.
The outlook for burrowing owls in Alberta and in Canada could be quite bright if we continue to give them care and consideration. The birds are adaptable and tolerate limited human disturbance. They can live close to people and still successfully raise their young as long as they are not disturbed. They help farmers by eating large numbers of insects and some rodents, many of which are farm pests. Burrowing owls survive well in habitats that are kept open and the vegetation cropped low to the ground. Thus, they are found often in pastureland, grazing leases, and grazed farmyards. Burrowing owls are being bred successfully in captivity at the Calgary Zoo.
Alberta currently has the habitat to support 1000 breeding pairs of burrowing owls. The initial goal of Natural Resources Service is to reach 850 pairs in the province. A primary tool in reaching that goal will be public awareness and willingness to help protect areas suitable for burrowing owls. Anyone willing to aid in the management of this species by reporting nesting sites is encouraged to contact the Fish and Wildlife Division.
For further information on the burrowing owl, check out the Status of the burrowing owl in Alberta report, contact your local Fish and Wildlife Office or write to:
Wildlife Management Branch
Fish and Wildlife Division
Alberta Sustainable Resource Development
9915 -108 Street
Edmonton, Alberta
T5K 2G8
