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Image Credits: top photos by D. Low, sketch in "Birds of British Columbia", Campbell et al. bottom photo taken by Dick Cannings, Royal British Columbia Museum, Historical facts Historically, Burrowing Owls in British Columbia bred mainly in the Okanagan-Similkameen and south Thompson basins: Osoyoos, Oliver, Penticton, White Lake, Coldstream, Okanagan Landing, Knutsford, Savona, Kamloops, Douglas Lake and Lulu Island in the Fraser Delta; with occasional records over a slightly wider area in southern British Columbia - east to the Kootenay River valley, north to Horsefly in the interior and north to Comox on the coast. Last breeding record in 1970. Designated threatened in 1979 and reconfirmed as threatened in 1991; re-examined in 1995 and uplisted to endangered. Except for some recent nests derived from introductions, its true breeding status is not clear but there may still be a few isolated nesting pairs in the Okanagan Valley each year. The reintroduction of Burrowing Owls has not been successful in establishing a stable population. Within the owl family, Burrowing Owls; being a grassland rather than a forest species, are unusual in many respects: they live in underground burrows, are often active in broad daylight, and eat insects as well as rodents. Ranked second to the Barn Owl as the most economically beneficial owl in North America because it eats so many insects and rodents near agricultural areas. Another distinguishing feature of the owl is its tolerance of non-threatening human activity. Nests are sometimes found in cow pastures near farm buildings, on airports, or on road right-of-ways. This tolerance, together with its habit of loafing around the nest burrow or on fenceposts in daylight, make this one of the most observable of all owl species. The Burrowing Owl has been described as a short fat owl on stilts. The long, almost bare legs and stubby tail of this plump-looking little owl are indeed distinctive. It is similar in size to the American Robin, with a total length (head to tail) of about 24 cm. Long legs help this "ground owl" see over the low "short-grass" prairie vegetation in a landscape with few elevated perches, and also aid in running down insect prey. Female Burrowing Owls are slightly smaller than males, an uncommon situation for birds of prey. This may be an adaptation for squeezing into narrow burrows. The sexes have similar colouring, although males often appear faded, possibly from spending more time exposed to the sun. Adults are a rich sandy-brown colour, thickly spotted with whites and buffs on the underparts; the underparts are whitish, barred with brown. This colouring provides good camouflage in dry grassland habitats. Other features include a rounded head without ear tufts, yellow eyes, white eyebrows, and a white throat with a dark brown half-collar. Juveniles have buffy underparts without bars during the first few weeks after emergence from the burrow. Map British Columbia North America In the U.S.A., Burrowing Owls have a wide distribution in open, well-drained grasslands, steppes, deserts, prairies, and agricultural lands. They occur in all states west of the Mississippi Valley, breed south through the western and mid-western States; and are resident in Florida. They extend south into Mexico, Central America and South America but populations have declined in many areas due to human-caused habitat loss or alteration. Over much of the owl's range, it is most abundant in active colonies of ground squirrels or prairie dogs, where numerous nesting and satellite burrows are available. This indicates that the availability of burrows is a major factor controlling the abundance of Burrowing Owls. Burrows dug by badgers are also important in many areas. In British Columbia there are relatively few burrowing mammals in habitats that are otherwise suitable for this owl. A viewing site, marked with a sign, has been set up north of Osoyoos Lake on Black Sage Road, where the birds can be viewed from a distance without disturbance. The overall abundance of Burrowing Owls is limited by the availability of suitable habitat. The grasslands in which they live are restricted to the dry valley bottoms of the southern interior, and comprise less than one percent of the area of the province. This small area of natural grassland is being further diminished by expanding towns, intensive agriculture, and a multitude of other industrial uses and developments, especially in the Okanagan Valley. The quantity and quality of grassland has declined substantially across the Canadian Prairies with most striking losses occurring between 1976 and 1986 for conversion to croplands. The Burrowing Owl used badger holes and when cattle were introduced to the grasslands the badgers were shot because of the holes they made. Badgers probably declined as a result of over-hunting, habitat loss and habitat fragmentation. The development of grasslands and sagebrush steppe for other uses has also reduced population numbers. Control of problem wildlife or other mortality factors affecting burrowing mammals, such as badgers and ground squirrels, results in lack of burrows. As well, susceptibility to pesticides (notably Carbofurans), either directly or by ingestion of prey species containing pesticides can affect habitat quality both directly and indirectly, by causing adult mortality and low reproductive success. Heavy grazing pressure may lead to disturbance, burrow damage and degradation of nearby foraging areas by eliminating tall grasses. Burrowing Owls also have to contend with many natural hazards, such as predators and weather-caused mortality. However, the addition of human-caused mortality and habitat degradation has caused population declines in many areas. A BC Environment program has attempted reintroduction of this species since 1983. Financially supported by the Habitat Conservation Fund, the partially successful program is carrying out a captive breeding program for release of Burrowing Owls. Since the 1980s, when about 500 individuals were transplanted as family units from Washington State, the population status has improved. Primarily juveniles, the owls were transplanted to recovery areas near Vaseux and Osoyoos lakes from 1983 to 1990. They were placed in artificial burrows made from plastic pipe with an inverted bucket at the end for a nest chamber. Adult owls showed a strong attachment to their broods and continued to care for them despite the disruption of the move. The program also included construction of satellite burrows to provide cover for adult males and to give the developing young space to spread out. The South Okanagan recovery program has been initially encouraging. During the years 1986 through 1992, 87 introduced owls have returned as adults and have produced a total of about 90 fledged young. Similar but smaller introduction programs have also been carried out at Cache Creek and Douglas Lake, using juvenile owls hatched in captivity at the Owl Rehabilitation Centre in Ontario. The long-term success of these programs is dependent on whether self-sustaining populations are established. As of 1995, there were between 5-10 breeding pairs existing in the province due to the reintroduction programs. Emphasis of the Burrowing Owl recovery program is now on captive breeding in wildlife rehabilitation centres, including Stanley Park in Vancouver and the Kamloops Wildlife Park. The long-term goal of BC Environment is to establish self-sustaining populations of at least ten breeding pairs of owls in each of five different locations in the southern interior. The program is part of the National Recovery Plan developed in cooperation with Alberta, Saskatchewan, Manitoba, the Canadian Wildlife Service (CWS), and the World Wildlife Fund (WWF). The outlook for Burrowing Owls in British Columbia is reasonably good. Although habitat loss is an on-going problem, many human-cause impacts are lower now than in earlier years. With public support, these curious little ground-owls may become firmly and permanently established in southern grasslands. Although the Burrowing Owl has almost disappeared from the Okanagan Valley, perhaps the recent introductions will help it regain a secure place in the Okanagan fauna. We can hope that it may once again become even more common than in 1909 when E.P. Venables of Vernon wrote: "...sometimes in the evening the call note may still be heard, but it comes from a long distance, and is a rare sound." It is a migratory summer visitor, usually appearing in the Okanagan Valley in April. The beginning of southward migration if difficult to determine from the few records available, but the date of the disappearance of adults and young from the nest site ranges from mid-July to the beginning of October. Adult females migrate earlier than young. Adults usually leave late July to early August whereas juveniles usually leave August to September. Most autumn migration probably takes place in September. Wintering locations of birds from the interior are unknown but are thought to be south of the United States-Mexico border. The individuals occasionally seen on the south coast of British Columbia during winter are probably from nests in the Fraser River Delta. Although Burrowing Owls are known to winter occasionally around the Strait of Georgia on the Pacific Coast, there is only one winter record for the Okanagan (1963). Breeding Nests of the Burrowing Owl are usually built in the abandoned burrows of Yellow-bellied Marmots, Belted Kingfisher, Striped Skunks, Prairie Dog, ground squirrels, badgers and occasionally fox. Nests have even been recorded near White Lake in an old drainpipe and in a natural crevice in a railway embankment. Both sexes prepare the burrow for nesting, using feet, beaks and wings to scrape out dirt. They often begin these renovations at several burrows, eventually selecting the best one as a nest site. This is then lined with horse or cow dung or other material. It has been speculated that the lining material acts as an absorbent, attracts dung beetles eaten by the owls, masks odours produced by the birds (making detection by predators more difficult), or produces heat by decomposition, aiding in the incubation of the eggs. Six to ten white eggs are laid at the end of the sloping tunnel on the floor of the nest chamber covered with dried horse or cattle droppings. Eggs have been found during the month of May and young at the beginning of June. The female incubates the eggs for three to four weeks. The male brings food to the female during incubation, and stands guard near the burrow by day. Hatched young stay in the nest chamber for about two weeks. By this time the young are large, the burrow is very crowded, and they will often stand at the burrow entrance eagerly waiting for the parents to bring food. Young birds have been observed outside the nest hole (when about 4-6 weeks old) from June to October. The young owls begin flying at about this time and can fly quite well when six weeks old. They start to hunt for themselves seven or eight weeks after hatching but can catch insects on the ground even before they can fly. During this period the female remains near the burrow and helps to distribute food brought in by her mate. Once the young owls are active above ground, the family often uses several burrows in the immediate area. The Penticton nest (1970) provides the most complete breeding chronology. Burrowing Owls have an incubation period of 28 days and the young emerge from the nest at two weeks of age. Behaviour Burrowing Owls are most active at night but often hunt during daylight, mainly in the early morning and late afternoon, especially when they have young to feed. They may be seen standing at the burrow entrances throughout the day or sitting on posts and other perches. The owls have often been reported to nest in loose colonies. Such groupings may be a response to local abundance of burrows and food, or an adaptation for mutual defense. Colony members can alert each other to the approach of predators and join in harassment of them. During the nesting season, adult males forage over home ranges 2 to 3 square kilometres in size and the ranges of neighbouring males may overlap considerably. A small area around the nest burrow is aggressively defended against intrusions by other Burrowing Owls and predators.
Diet or Growing requirements The entrances to burrowing owl burrows are usually littered with feathers of small birds, rodent, reptile and amphibian bones and fragments of insects such as grasshoppers and ground beetles, and even cherry stones. In the Okanagan Valley, recorded prey items include the Great Basin Pocket Mouse, Western Harvest Mouse, voles, crickets, beetles, scorpions, and grasshoppers. On September 27, 1984, 19 pellets found at a nest of introduced owls at the north end of Osoyoos Lake contained the skulls of 12 Great Basin pocket mice, the remains of at least 40 sand crickets, 7 ground beetles, and 1 darkling beetle. Like other owls, this species probably relies on acute hearing as much as eyesight for capturing prey at night. Besides leaving food remains, Burrowing Owls collect what seem to be fascinating material - pieces of cardboard, scraps of cloth and tufts of cattle hair have been found around Okanagan nests. Burrowing Owls daily consume about 15 percent of their body weight. Undigested food remains (mostly hair, bones, and insect parts) are regurgitated in the form of two or three pellets per day, and these accumulate around the burrow, providing an indication of what has been eaten. The pellets are cylindrical in shape, 3 to 4 cm long and about 1.5 cm thick. The owls are quite versatile in the ways they capture prey. They chase down grasshoppers and beetles on the ground, use their talons to catch large insects in the air, or hover in mid-air before swooping down on unsuspecting prey. They also watch patiently from perches, then glide silently toward their target. Predators Predators, mostly of eggs and young owls, include weasels, skunks, and snakes. Because Burrowing Owls do not nest in trees, they have many potential predators as well. The predators are of two general types: 1) predators that enter or dig up burrows to eat eggs, nestlings, and/or adult females; or 2) predators that prey on older nestlings and adults when they are above-ground. In Canada, mammals that can potentially access nest chambers and are therefore possible predators are: badgers, foxes, striped skunks, weasels, and raccoons. Species that mainly catch owls above the ground are: coyote, domestic dog, cat, Swainson's Hawk, Great Horned Owl, Ferruginous Hawk, Northern Harrier, Short-eared Owl, and Prairie Falcon. Badgers, skunks, and long-tailed weasels seem to present the most serious threats to female Burrowing Owls and their eggs in Canada, while avian predators cause the majority of mortalities in adult males and fledglings. Related On-line Sites to Visit Publications this section sponsored by:
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