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Articles

Vol. 32 No. 2 (2001)

OCCURRENCE PATTERNS OF PEREGRINE FALCONS ON SOUTHEAST FARALLON ISLAND, CALIFORNIA, BY SUBSPECIES, AGE, AND SEX

Submitted
September 24, 2025
Published
April 1, 2001

Abstract

We summarize observations of 201 Peregrine Falcons (Falco peregrinus) at Southeast Farallon Island during the fall and winter from 1990 to 1999, categorized by age, sex, and subspecies. The northwestern subspecies (F. p. pealei) and the continental subspecies (F. p. anatum) occurred with roughly equal frequency. We recorded 10 individuals of the arctic subspecies (F. p. tundrius). During fall, adults occurred significantly earlier than immatures. Males tended to occur earlier than females, and anatumtended to occur earlier than pealei. Four to six birds per year (of both anatum and pealei) remained through the winter. Under the assumption that wintering individuals returned each year to the maximum extent possible allowed by the observed variation by age, sex, and subspecies, their survival rate was 0.78.

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