Burrowing Owls

Until the 1970s, Burrowing Owls had healthy populations in Canada’s three prairie provinces but was already gone from the grasslands of British Columbia. Today, it breeds in Alberta and Saskatchewan, with some rare appearances in southwestern Manitoba. These prairie owls migrate 2,500 to 3,500 km to winter in south Texas and central Mexico.

In addition, captive-bred Burrowing Owls breed in and some return to the grasslands near Kamloops, British Columbia, where they are introduced each spring.

Most British Columbia owls migrate to the west coast from Washington to California. In the south, Burrowing Owls live in agricultural fields, as well as in more open, grassland country, orchards, and even thorn shrub woodlands.

Many Burrowing Owls that breed in Canada do not return. Only half of the adult Burrowing Owls come back to their northern breeding grounds, and a mere 6 percent of young owls return to breed in Canada the year after they are born. Scientists are trying to learn if the owls that do not return are breeding elsewhere, or die in winter.

At one time, the Burrowing Owl was common in the four western Canadian provinces. Now, it is one of the most endangered birds in Canada. The population decline began in the 1980s and accelerated during the 1990s to an average rate of 22 percent a year. In 1977, more than 2,000 breeding pairs of Burrowing Owls lived in Canada; by 2000, the number of pairs had dropped to fewer than 1,000.

Human activity has a great impact on the Burrowing Owl. Chemical pesticides, applied to control ground squirrels and grasshoppers, sometimes poison the Burrowing Owl. Strychnine-covered grain has also killed owls that eat the grain that is left in burrows to kill ground squirrels. Pesticides also kill animals and insects that the Burrowing Owl eats. This may force the bird to hunt far from the safety of its nesting site, making it more susceptible to predators and other dangers.

The extermination of burrowing mammals, particularly badgers and ground squirrels, often killed as “pests,” reduces the number of suitable homes for the Burrowing Owl. Fewer of these digging animals means fewer nests and nearby roost, or resting, burrows for the birds.

Burrowing Owls sometimes die along roads. Young owls in particular hunt on and beside roads at night. Because they are slow flyers and have difficulty escaping oncoming traffic, they are often killed.

Habitat loss and changes in the quality of habitat reduce hunting and nesting territories and are associated with low birth and high death rates among Burrowing Owls. In Canada, less than 24 percent of the original prairie habitat remains. Native grasslands lost to housing, farming, roads, and energy exploration have eliminated some of the bird’s living space or changed it into something that the Burrowing Owl can no longer use.

In 1995, the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) declared the Burrowing Owl endangered, meaning that it may soon no longer exist in the wild in Canada. The Burrowing Owl has been designated as a species at risk in all four western Canadian provinces and is protected under provincial wildlife acts from capture, harassment, trade, killing, or nest disturbance. The Convention on International Trade in Endangered Species also protects the Burrowing Owl.

A national Burrowing Owl recovery team, a program that includes governmental and non-governmental groups, approved a recovery plan in 1995 and updated the plan in 2002. This plan aims to increase Burrowing Owl populations in Canada to levels where they can sustain themselves.

In addition, the recovery team members are involved in the experimental release of captive-bred owls in Saskatchewan and the reintroduction of owls in British Columbia. Few of the birds released in Saskatchewan have returned there. Some of the more than 250 birds introduced into the Kamloops region of British Columbia since the program began in 1989 have mated and produced young, and a few have returned to British Columbia the following spring.

Despite its efforts, the recovery team has not been able to identify the key factors behind the population decline, although research has shown that some combination of factors is to blame. To help it reach some conclusions, the team is working to gather information about migration, winter range, changes on the breeding grounds, mortality, and the effects of various land uses on the owl.

One of the reasons assembling this knowledge is taking time is because Burrowing Owls are difficult to track. They are very cryptic, or hard to see because of coloration that camouflages them. They migrate at night and fly alone, not in flocks. In addition, because of their small size, they cannot carry satellite transmitters like those used on larger birds, making it necessary for biologists to attach smaller radio transmitters with shorter ranges.

A number of governmental and nongovernmental programs in Canada’s four western provinces are conserving habitat for the bird, studying its habits, banning the use of some pesticides, and raising awareness about the needs of the Burrowing Owl. Through two nongovernmental programs alone—Operation Burrowing Owl in Saskatchewan, which began in 1987, and Operation Grassland Community in Alberta, which started in 1989—more than 700 landowners have conserved roughly 70 000 hectares of Burrowing Owl nesting habitat.

Operation Burrowing Owl – Saskatchewan
Wildlife Preservation of Canada – Burrowing Owl Program
Nature Canada Blog –  Recovery Strategy for Endangered Burrowing Owl Incomplete

 

One Response to Burrowing Owls

  1. nest boxes says:

    It would be a real shame to let these birds decline further. They look very similar to the UK’s “Little Owl” which is our smallest species. Although we do not have any that burrow, our “Small Eared Owl” is known to nest on the ground.

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