Breeding Site Faithfulness, Reproductive Biology, and Adult Survivorship in an Isolated Population of Cassin's Finches

Publication Type:Journal Article
Year of Publication:1985
Authors:L. Mewaldt, R, King, JR
Journal:The Condor
Date Published:1985
ISBN Number:00105422
Keywords:Burrica, Burrica cassinii, Carpodacus, Carpodacus cassinii, Fringillidae, Haemorhous, Haemorhous cassinii
Abstract:We used mist nets in a capture-recapture demographic study of the birds of an isolated relict grove of ponderosa pines (Blue Sky) on Hart Mountain in southern Oregon. Cassin's Finches (Carpodacus cassinii), usually considered nomadic, returned each spring. Females were more faithful to breeding site than males. As evidenced by cloacal swelling and incubation patch formation, 96% of females laid eggs in the 18 days following 24 May. When June snow storms destroyed most nests in 1975 and 1979, many females attempted second nestings. Most apparently abandoned these second nestings in early July when the finches left Blue Sky to wander more widely over Hart Mountain while they underwent their annual molts. Most yearling females and males were sexually active and apparently nested. Although obscured by reduced mobility of females during incubation and early brooding, the sex ratio was close to 50/50. There were 20 to 25 pairs per hectare of suitable (pine) finch habitat. Breeding density may be limited by the zone around the female that is defended by the male during nest-site selection and nest building. The minimum annual survival rate for finches one year old and older was 0.64 (SE = ± 0.02) for males and 0.60 (SE = ± 0.03) for females.
Short Title:The Condor
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