| The Loggerhead shrike is a medium-sized passerine with
a grey back, black wings, white breast and a notable black mask around the eyes
extending across the forehead. Although the Loggerhead shrike is a songbird, it
has a predatory lifestyle. While shrikes have a strong, hooked beak resembling
that of a bird of prey, they lack strong talons and must impale larger prey on
thorny trees, or barbed wire. This serves a number of functions: it secures
larger prey items while the shrike tears them into pieces that can be eaten; it
provides a store of food; and it serves as a courtship display by males to
attract females to a potentially successful mate and territory.
The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) became concerned as to the status of the Loggerhead Shrike (Lanius ludovicianus) in the early 1980's and designated the eastern subspecies as threatened in 1985 (Cadman, 1985). Due to the continued decline in numbers, the small size of the remnant population and threats to the species' primary breeding sites, their status was upgraded to endangered in 1991, while the status of the Great Plains population was upgraded to threatened.
Distribution and Abundance in Canada
The Loggerhead shrike has a widespread distribution throughout North America, with three subspecies being found in Canada (Godfrey 1979). Lanius l. migrans, the Eastern subspecies, was formally found in Manitoba, Ontario, Québec, New Brunswick and Nova Scotia, but is now restricted only to southern Ontario. Lanius l. excubitorides, the Great Plains subspecies, breeds in southwestern Manitoba, central and southern Saskatchewan and Alberta. Lanius l. gambeli is a northwestern United States subspecies which has been recorded as a rare transient in British Columbia.
Numbers of Loggerhead shrikes in eastern Canada have declined since 1900, especially in the last 25 years (Cadman 1985). Extensive annual surveys began in the core areas in 1992 to monitor the species' population. As shown to the left, the number of shrikes in the province has decreased substantially since then and the population is now at extreme risk of extinction in Ontario.
The current wild population of migrans birds is estimated at 20-25 pairs
situated entirely in southern Ontario. At present in Ontario, it breeds almost
entirely in three core areas, all of which are located on limestone plains
immediately adjacent to the Canadian Shield. The map to the right shows the
approximate locations of these three core areas within the shrike's historic
range in Ontario. The current wild population of excubitorides birds is
estimated at close to 4000 situated in Alberta, Saskatchewan and Manitoba..
Captive Breeding of Loggerhead Shrikes at the ASCC
1992, the ASCC established a colony of western Loggerhead Shrikes (Lanius
ludovicianus excubitorides) using 19 young collected from Saskatchewan.
Between 1994 and 1996, this colony was used to develop management and captive
breeding techniques for the critically endangered eastern subspecies (L.
l. migrans). In 1997, 15 wild shrike nestlings were collected, and 8
were raised at the ASCC by curator Ian Ritchie. The remaining 7 went to
the Toronto Zoo, the other main partner
in this important breeding effort. Work at both facilities has
found that collecting young at eight to 10 days of age is the most effective way
of obtaining a breeding stock. At the ASCC, once the young have been
hand-reared to the fledging stage, they are transferred to large flight rooms
where various young birds grow up together until the onset of winter. They are
then moved to individual holding pens in a heated room for the winter.
Cadman, M.D. 1985. Status report on the Loggerhead Shrike (Lanius ludovicianus) in Canada. COSEWIC report, Ottawa, Ont.
Canadian Wildlife Service. 1993. Loggerhead Shrike. Hinterland Who's Who publication. Environment Canada.
Chabot, A.A., R.D. Titman and D.M. Bird. 1995. Habitat selection and breeding biology of Loggerhead Shrikes in Eastern Ontario and Québec. in Yosef, R. and F.E. Lohrer (Editors). Shrikes (Laniidae) of the world: Biology and Conservation. Proceedings of the Western Foundation of Vertebrate Zoology 6(1):155-156.
Gawlick, D.E. and K.L. Bildstein. 1990. Reproductive success and nesting habitat of Loggerhead Shrikes in North-Central South Carolina. Wilson Bull. 102(1): 37-48.
Godfrey, W.E. 1979. The Birds of Canada. National Museum of Natural Sciences, Ottawa, Ont.
Haas, C.A. and S.A. Sloane. 1989. Low return rates of migratory Loggerhead Shrikes: winter mortality or low site fidelity? Wilson Bull. 101: 458-460.
Johns, B., E. Tefler, M. Cadman, D.M. Bird, R. Bjorge, K. DeSmet, W. Harris, D. Hjertaas, P. Laporte, R. Pittaway. 1994. National Recovery Plan for the Loggerhead Shrike. Report No. 7. Ottawa: Recovery of Nationally Endangered Wildlife Committee. 32 pp.
Long Point Bird Observatory. 1997. Endangered Loggerhead Shrikes and other grassland birds: a landowner's resource guide. Canadian Wildlife Service, Long Point Bird Observatory. 11pp.
Robert, M. 1989. Les oiseaux menacés du Québec. Environment Canada, Canadian Wildlife Service, Quebec City, Que.
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