Site Fidelity and Annual Survival of the Western Yellow-breasted Chat (Icteria virens auricollis) at the Northern Edge of its Range

Résumé

We studied return rates, site fidelity, dispersal, and survivorship of an endangered population of the Western Yellow-breasted Chat (Icteria virens auricollis) in the southern Okanagan River valley, British Columbia, between 2001 and 2007. Between 2001 and 2006, we banded a total of 75 adults and 385 nestlings. Apparent survival for male Western Yellow-breasted Chats banded as adults was 65%, and survival and recapture were constant across time. Other results were as follows: 44% of males and 13% of females banded as adults were re-sighted during the period 2002–2007; 33% of males and 10% of females were re-sighted the year after they were banded; 31% of males and 10% of females had fidelity to the study site where they were banded as adults; 10% of Western Yellow-breasted Chats banded as nestlings returned and, of these, 62% of males and 54% of females returned to their natal study site to breed. The dispersal distance for males banded as adults (n = 5) that did not return to their sites ranged from 6.4 km to 42.9 km. Natal dispersal ranged from 2.5 km to 15.6 km for males (n = 7) and 2.3 km to 2.6 km for females (n = 2); 16 males and 7 females banded as nestlings did not disperse. These findings contrast with predictions that species at the northern limit of their range will have low site fidelity and return rates and higher dispersal distances than passerine populations at the core of their range.