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Turnover and recruitment in a tundra population of Peregrine Falcons Falco peregrinus
Author(s) -
COURT G. S.,
BRADLEY. D. M.,
GATES C. C.,
BOAG D. A.
Publication year - 1989
Publication title -
ibis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.933
H-Index - 80
eISSN - 1474-919X
pISSN - 0019-1019
DOI - 10.1111/j.1474-919x.1989.tb04785.x
Subject(s) - tundra , population , biological dispersal , demography , nest (protein structural motif) , geography , peregrinus , ecology , biology , zoology , arctic , biochemistry , sociology
The population dynamics of tundra‐nesting Peregrine Falcons Falco peregrinus tundrius was studied over 7 years on a 450 km 2 study area in the Keewatin District of Canada's Northwest Territories. Peregrines showed strong fidelity to nest sites; none of 25 males ringed changed territories, while five of 38 females ringed were recorded changing territories. Such changes usually occurred after nesting failure. Annual turnover of territorial adults was estimated to be 22% (15% for males and 26% for females). Annual mortality of adults was estimated to be 17% (15% for males and 19% for females). If we assumed that territory vacancies, in addition to mate replacements, were indicative of mortality, then maximum annual mortality was estimated at 24% for each sex. Territories were held only by adult Peregrines. The oldest male on territory was at least 7 years old, the youngest was 2. The oldest female on territory was at least 7 years old, the youngest was 3. Territories were held by individuals of each sex for at least 6 years. One pair remained together for at least 4 years. Less than 4% of all young Peregrines produced on the study area in the first 5 years of the study were recruited into the breeding population. More male than female young were recruited despite an even sex ratio among nestlings. Peregrines did poorly in their first breeding attempts. The single young female recruited into the study population dispersed more than three times the median dispersal distance of six recruited males, suggesting that other females probably dispersed beyond the boundaries of the study area.