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Wintering site fidelity and movement patterns of Western Sandpipers Calidris mauri in the San Francisco Bay estuary
Author(s) -
WARNOCK SARAH E.,
TAKEKAWA JOHN Y.
Publication year - 1996
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.1996.tb04323.x
Subject(s) - calidris , bay , sandpiper , home range , estuary , geography , range (aeronautics) , fishery , ecology , oceanography , habitat , biology , geology , archaeology , materials science , composite material
Western Sandpipers Calidris mauri are the most numerous shorebird species in the San Francisco Bay estuary during winter. A sample of 106 Western Sandpipers was captured in mist nets and radio‐marked with 1‐g transmitters to examine their wintering site fidelity and movements. Differences in distances moved, home range extent and core area size were examined by age, sex, season, site, time of day and tide. All birds remained in the south San Francisco Bay region during winter and exhibited strong site fidelity, with a mean home range of 22.0 km 2 or only 8% of the study area. First‐year birds had larger home ranges (26.6 ± 3.6 km 2 ) than adults (17.2 ± 2.5 km 2 ) in winter, but home range sizes of males and females were not significantly different in any period. Home range sizes were similar between seasons, but core areas were smaller in spring (6.3 ± 1.2 km 2 ) than in early (9.6 ± 4.0 km 2 ) or late (11.6 ± 1.6 km 2 ) winter. Movements and home range size were similar for radio‐marked birds located during day and night. The high degree of regional and local site fidelity demonstrated that the mixture of natural mud fiats and artificial salt ponds in southern San Francisco Bay provided sufficient resources for large wintering populations of Western Sandpipers.