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A Vignette on the Birds of Prey

Birds of prey are found in a wide range of colors, shapes, and sizes. There are approximately 420 different types of birds included in the group. Most of them are either eagles, falcons, hawks, or vultures, but 139 different kinds of owls are also included. The variety of birds that are grouped together as Birds of Prey are often very dissimilar from each other. Owls, for example, are built differently from eagles and hawks. The owl hunts in much more trying conditions. They are nocturnal predators, while eagles and hawks are daytime hunters ( Wexo, 1991). At night, visibility is greatly reduced making prey difficult to find under the dim light of the moon. Further complicating this is the structure of the owl's eye which is designed for daylight vision. In addition, owls must hunt in complete silence as sound is enhanced in the still night air. Even the slightest noise would be detected by the acute hearing of the owl's prey. But the differences seem immaterial compared to the one great skill all birds of prey have in common which is their ability to take live prey. Other birds may also hunt, but none are nearly as skilled at it as the birds of prey (Runtz, 1996).

The Burrowing Owl (Speotyto cunicularia) in particular is a small, fossorial bird of prey that is dispersed discontinuously throughout the grasslands of North America. In Canada, it is a summer resident that breeds in the southern regions of Alberta, Saskatchewan, Manitoba and in the southern interior of British Columbia. The winter distribution of Canada's owls is currently unknown but is believed to be south of the United States-Mexico border. Breeding Burrowing Owls requires an adequate nest burrow in an open area engulfed in short vegetation, and enough permanent vegetative cover to provide a sufficient amount of prey. The quantity and quality of such grassland habitat has decreased substantially on the Canadian prairies. The most noticeable loss had occurred between 1976 and 1986. The conversion of grassland to cropland has slowed a considerable amount since then. Accompanying this decrease in habitat is an increase in habitat fragmentation, pesticide use, and predator populations all of which are contributing factors to the decline in Burrowing Owl populations. In addition, the migration route, wintering areas, and collisions with vehicles are also contributing to higher mortality in the Burrowing Owl. Presently, the breeding population in prairie Canada is at an historical low ranging between 1010 and 1685 pairs and the small number of owls in British Columbia (5-10 pairs) exist due to the intensive reintroduction programs. The density of owls has diminished greatly in the converge of their Canadian range, and they have vanished from much of the periphery, in particular the eastern and northern portions. Extensive surveying over the last seven years has revealed a rapid population decline (Wellicome and Haug, 1995). In fact, the population of Burrowing Owls nesting in Canada has been in decline since the mid-1900s, when modern agricultural practices began. However, this decline has significantly accelerated to the extent that the Burrowing Owl is now listed as endangered by the Endangered Wildlife Committee in Canada. Although moderate populations remain in Saskatchewan and Alberta, it has disappeared from some regions, and present trends indicate that many other regions will no longer have Burrowing Owls within 10 years. There is an urgent need to examine this trend and take immediate action to reverse it while an adequate population remains (Canadian Burrowing Owl Recovery Team, 1995).

The intentions of the Burrowing Owl recovery plan are to reverse the population decline across the Canadian prairies, subsequently maintain a stable population of at least 3000 pairs, and to re-establish a self-sustaining population in British Columbia averaging at least 50 pairs (Wellicome and Haug, 1995). As the population continues to decline in Canada, it becomes more difficult to accomplish these objectives. Therefore, it is essential to preserve historic nesting sites by encouraging land-owners to maintain small parcels of pasture in their present condition. It is also important to install artificial nest burrows in areas that are lacking. In addition, it is essential to maintain a 600-m radius surrounding nest burrows free of pesticide and herbicide application, gopher control, and other human disturbances that might jeopardize survival of both young and adult owls. All areas considered for installation of artificial nest burrows or release programs should be located at least 600-m from both primary and secondary roads. Also of great importance is to preserve uncultivated areas of dense vegetation within a 600-m radius of nest burrows in order to supply habitat for prey used by Burrowing Owls (Haug and Oliphant, 1990).

Birds of prey are in great danger. Their numbers have been drastically reduced over the last few years since people have been killing them in a variety of ways. Some people shoot and trap birds of prey because they are said to kill a numerous amount of farm animals. However, this is a mistaken idea. Birds of prey tend to kill relatively few farm animals. Instead, the main food source of birds of prey are the animals that are the farmers' worst enemies such as mice, rats, insects and other crop destroyers. Pesticides are yet another great danger to the birds of prey. Continuously, small animals absorb small quantities of pesticide. The amount may not be enough to kill them, but it does stay in their bodies. As birds of prey digest insects and rodents the amounts of pesticides in their bodies becomes increasingly toxic, often to the point of death. A third major danger is human population. As people convert wild places to housing developments and farms, the hunting territories are destroyed, leaving the birds with little or nothing to eat. The birds either leave or eventually die (Wexo, 1991).

It is not to late for people to take initiative and save the birds of prey. But in order to do this we must stop shooting and trapping these birds, using the kinds of pesticides that accumulate in the bodies of animals, and destroying wild areas. However, if areas must be destroyed the least we can do is relocate the birds to insure their survival.

Zoos and other animal care organizations have implemented programs to breed endangered birds of prey. Unfortunately, this will not guarantee the long-term survival of many species unless we all make conditions safer for the birds.

References

Canadian Burrowing Owl Recovery Team. (1995). National Recovery Plan For The Burrowing Owl (RENEW Report No. 13). Ottawa, Ont: Scientific and Technical Documents Division of the Canadian Wildlife Service.

Haug, Elizabeth A., & Oliphant, Lynn W. (1990). Movements, Activity Patterns, And Habitat Use Of Burrowing Owls In Saskatchewan. J. WildL Manage.54(1), 27-35.

Runtz, Michael W. (1996). Owls; Animal Behavior. Nature Canada.25(3), 42-43.

Wellicome, Troy I., & Haug, Elizabeth A. (1995). Second Update Of Status Report On The Burrowing Owl Speotyto Cunicularia. Ottawa, Ont: Committee On The Status Of Endangered Wildlife In Canada.

Wexo, John Bonnett (1991). Birds of Prey. Published by Creative Education.

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