.PTOR POPULATION CHANGES:

chers migrate as far south as Argentina and Chile.

excerpts from Bird Trends # 4, 1994/5

The latest issue of Bird Trends reports on the population status and trends of Canada's birds of prey (raptors). Complete copies of this report are available from ‘the .Migratory' Birds Conservation Division, Canadian Wildlife Service, Ottawa KIA 0H3.

"Responsibility for the management of the 35 raptor species that breed in Canada rest with the provinces and territories, not the federal government. The focus of raptor conservation by these jurisdictions has therefore been almost exclusively within their borders. Most raptors that breed in Canada migrate south during our winter, to the USA or the countries of Latin America. Nevertheless, raptors are not included under the 1916 Canada - US Migratory Birds Convention, nor under any formal conservation agreements between Canada and these nations. A partial exception is CITES, the Convention on International Trade in Endangered Species, which restricts trade in wildlife among signatory countries and under which all species of Canadian raptors are listed. However, CITES does not address aspects of species conservation other than trade.

Twelve species or subspecies of birds of prey have been designated of national conservation concern by COSEWIC (Committee on the status of Endangered Wildlife in Canada). Thus six of 21 species and subspecies of diurnal (day active) raptors and six of 16 species of owls that breed in Canada are listed as vulnerable, threatened, or endangered, a higher proportion than in any other species group. Many of these raptors in jeopardy migrate south of Canada in winter; some winter in the USA, and Little is known about

leir winter habitats or ecology, or the conservation issues that affect hem. Indeed, in the case of the Burrowing Owl, exactly where Canadian birds spend the winter is unknown.

Many conservation issues affect Canadian raptors. As a first step, we need to know more about the distribution and population status of many species. Most raptors are not well covered by current large~scale monitoring efforts such as the Breeding Bird Survey, a roadside survey particularly well suited to songbirds. Specialized surveys and monitoring efforts must be developed for raptors if we want to determine if any species are declining. ....Cha11enges for the conservation of birds of prey include contamination by persistent toxic chemicals in the environment; loss of food sources due to efforts to control wildlife of concern to agriculture; mortality associated with human activity (including shooting, disturbance, collisions with wires, vehicles, and buildings); and loss of suitable habitat. The last is perhaps the most fundamental problem facing all wildlife species." (excerpted from G. Holroyd, CWS, Introduction in Bird Trends # 4 1994-95)

"Raptors present special problems for estimating population status and trends. Firstly, they are usually widely dispersed, secretive species that nest at low densities. Secondly, breeding populations of some species may fluctuate over the short-term in response to fluctuations in abundance of their prey populations (e.g. Northern barrier, Northern Goshawk, Northern Hawk Owl, Short-eared owl, and Boreal Owl). Thus, many years of data are needed to detect non-cyclic long term trends in populations. Thirdly, the main survey techniques designed to census other bird species do not cover the remote regions where many raptors breed. Finally, many Canadian raptors

.Lgrate southwards for the winter and mix with birds from elsewhere in the

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