Peregrine falcon (pealei and anatum/tundrius) COSEWIC assessment and status report: chapter 2

Executive Summary

Peregrine Falcon
Falco Peregrinus
Pealei subspecies - Falco peregrinus pealei
Anatum / tundrius - Falco peregrinus anatum/tundrius

Species information

The Peregrine Falcon is a crow-sized, medium to large falcon with long, pointed wings.  Plumage and morphological differences exist between the three subspecies, Falco peregrinus anatum, F. p. tundrius and F. p. pealei that occur in Canada. Differences are, however, generally clinal, with paler birds occurring in dry areas and darker birds in wetter areas, and smaller birds in the north and larger birds in the south and west.

Recent genetic evidence suggests that the Pealei Peregrine Falcon is genetically distinct from the other two subspecies, but that historically the Anatum and Tundrius subspecies could not be distinguished genetically. Further, current differences between these two subspecies are weak and likely due to the limited gene pool associated with the introductions and introgression from non-Anatum birds from the USA.This report will consider Anatum and Tundrius Peregrine Falcons as a single designatable unit and Pealei Peregrine Falcons as a separate unit. Information on all three subspecies will, however, be included in the report because much of the available evidence is reported by subspecies.

Distribution

The Peregrine Falcon is nearly cosmopolitan in distribution breeding in Eurasia, Africa, Australia, North America and South America. The Anatum Peregrine Falcon breeds from the interior of Alaska, across northern Canada to southern Greenland, then south through continental North America to northern Mexico. In Canada, Anatums breed in all Canadian provinces and territories except Prince Edward Island, Nunavut, and insular Newfoundland. The Tundrius Peregrine Falcon breeds from Alaska, across northern Canada to Greenland. In Canada, the Tundrius Peregrine breeds from the northern Yukon east across the low Arctic islands, northern Northwest Territories and northern Nunavut to Baffin Island, Hudson Bay, Ungava and northern Labrador. The Pealei Peregrine Falcon is restricted to Pacific coastal areas and breeds from the Aleutian Islands and other coastal Alaskan islands south to Oregon. In Canada, the Pealei Peregrine Falcon breeds on the Queen Charlotte Islands, Triangle Island off the northern tip of Vancouver Island, the north and central BC coast, northern and western Vancouver Island, and eastern Vancouver Island and Gulf Islands south to Nanaimo. 

Habitat

The Peregrine Falcon inhabits a wide range of habitats from Arctic tundra, sea coasts, and prairies to urban centres. Most Peregrine Falcons nest on cliff ledges or crevices, but some will also use tall buildings and bridges near good foraging areas. At the landscape level, suitable nest sites are patchily distributed, but can be common locally in some areas. Extensive areas of Canada, where Peregrine Falcons are absent, appear to lack suitable nest sites and/or sufficient prey. Natural nesting habitat has not changed significantly since populations crashed and is still largely available, as are additional sites on human-made structures and in urban areas.

Biology

Peregrine Falcons prey primarily on birds. Burrow-nesting and cliff-nesting colonial seabirds, shorebirds, waterfowl, pigeons and songbirds are important prey for all subspecies. Peregrine Falcons are solitary breeders. Nests are scraped in substrate on cliff ledges. Nestlings leave the nest after about 40 days. Young are fed by adults and may remain in the vicinity of the nest site for three to six weeks after fledging.

Adult Peregrine Falcons demonstrate a high degree of breeding site fidelity and are known to reuse the same nest site for decades. Most juveniles disperse widely from natal areas. Peregrine Falcons are largely migratory although some coastal pairs and northern pairs are resident and may remain at nest sites through winter if food supplies are adequate. This is especially true for Pealei Peregrine Falcons and for urban-dwelling Anatum Peregrine Falcons in eastern Canada. In the fall, most Peregrine Falcons migrate south to the USA, Mexico and Central and South America. 

Population sizes and trends

National surveys to examine population trends of breeding Peregrine Falcons have been conducted in Canada every five years between 1970 and 2005. The surveys show substantial increases in Anatum and Tundrius Peregrine numbers since 1970, with notable increases between 2000 and 2005 survey periods. Although Pealei Peregrine Falcons escaped the large declines experienced by the two other subspecies, they did show declines associated with declines in prey. Their numbers have remained relatively stable, but lower than previously measured over this time period. Although these surveys are not designed to determine abundance, they can provide an estimate of minimum population size. Based on this information, the minimum population size in 2005 for Anatum Peregrine Falcons was 969 mature individuals and for Tundrius Peregrine Falcons 199. Together, a minimum population size for Anatum/Tundrius Peregrine Falcons in Canada is 1168 mature individuals. National survey information for Pealei Peregrine Falcons shows a minimum of 176 adult birds. Many additional breeding pairs of all subspecies exist, especially Tundrius Peregrine Falcons that breed in a vast, relatively uninhabited Arctic landscape.

Limiting factors and threats

The primary factor causing the decline of Peregrine Falcon populations was reproductive failure following exposure to organochlorine pesticides, particularly DDT. Declining trends of organochlorine levels in Peregrine Falcon tissues are encouraging and are linked with improved reproductive success. However, pesticide loads in some birds still exceed safe thresholds and organochlorine pesticides continue to be used in parts of the wintering range of Anatum and Tundrius Peregrine Falcons. A potential new threat from polybrominated diphenyl ethers has also been recently identified. These compounds bio-magnify in natural systems and are present in high concentrations in some Peregrine Falcons. Their effects are unknown.

Pealei Peregrine Falcon populations on Langara Island, British Columbia are known to fluctuate in response to changes in their seabird prey populations, declining as prey declines. Seabirds face threats from introduced mammalian predators at some sites and the Pealei Peregrine Falcons at those sites could decline if seabirds decline; the same may be true for marine coastal nesting Anatum and Tundrius Peregrine Falcons.

Other limiting factors include human disturbance at nest sites, potential for increased legal harvesting for falconry, and illegal harvest of eggs and nestlings for falconry.

Special significance of the species

The Peregrine Falcon has become an icon of the environmental movement in North America and elsewhere. The collapse of Peregrine Falcon populations in southern Canada and the USA helped galvanize a shift in widespread public attitude toward better environmental stewardship. 

Existing protection

The Peregrine Falcon is protected under the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), which restricts the import and export of birds and eggs in signatory countries. Like other raptors, Peregrine Falcons are not protected by the federal Migratory Birds Convention Act, but they are protected under provincial and territorial wildlife and endangered species acts. The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) has assessed, in 2000, Anatum as Threatened (Schedule 1 of SARA), while Pealei was assessed as Special Concern in 2001 (Schedule 1) and Tundrius was assessed as Special Concern in 1992 (Schedule 3). Species on Schedule 1 are provided protection by the federal government under the Species at Risk Act.

COSEWIC History

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) was created in 1977 as a result of a recommendation at the Federal-Provincial Wildlife Conference held in 1976. It arose from the need for a single, official, scientifically sound, national listing of wildlife species at risk. In 1978, COSEWIC designated its first species and produced its first list of Canadian species at risk. Species designated at meetings of the full committee are added to the list.  On June 5, 2003, the Species at Risk Act (SARA) was proclaimed. SARA establishes COSEWIC as an advisory body ensuring that species will continue to be assessed under a rigorous and independent scientific process.

COSEWIC Mandate

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assesses the national status of wild species, subspecies, varieties, or other designatable units that are considered to be at risk in Canada. Designations are made on native species for the following taxonomic groups: mammals, birds, reptiles, amphibians, fishes, arthropods, molluscs, vascular plants, mosses, and lichens.

COSEWIC Membership

COSEWIC comprises members from each provincial and territorial government wildlife agency, four federal entities (Canadian Wildlife Service, Parks Canada Agency, Department of Fisheries and Oceans, and the Federal Biodiversity Information Partnership, chaired by the Canadian Museum of Nature), three non-government science members and the co-chairs of the species specialist subcommittees and the Aboriginal Traditional Knowledge subcommittee. The Committee meets to consider status reports on candidate species.

Definitions

Wildlife Species

A species, subspecies, variety, or geographically or genetically distinct population of animal, plant or other organism, other than a bacterium or virus, that is wild by nature and is either native to Canada or has extended its range into Canada without human intervention and has been present in Canada for at least 50 years.

Extinct (X)

A wildlife species that no longer exists.

Extirpated (XT)

A wildlife species no longer existing in the wild in Canada, but occurring elsewhere.

Endangered (E)

A wildlife species facing imminent extirpation or extinction.

Threatened (T)

A wildlife species likely to become endangered if limiting factors are not reversed.

Special Concern (SC) Footnotea

A wildlife species that may become a threatened or an endangered species because of a combination of biological characteristics and identified threats.

Not at Risk (NAR) Footnoteb

A wildlife species that has been evaluated and found to be not at risk of extinction given the current circumstances.

Data Deficient (DD) Footnote c

A category that applies when the available information is insufficient (a) to resolve a species' eligibility for assessment or (b) to permit an assessment of the species' risk of extinction.

 

Canadian Wildlife Service

The Canadian Wildlife Service, Environment Canada, provides full administrative and financial support to the COSEWIC Secretariat.

 

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