eWestern Birds

Abundance and Site Fidelity of Migratory Birds Wintering in Riparian Habitat of Baja California

Steven C. Latta, Horacio de la Cueva, and Alan B. Harper

ABSTRACT: The ecology of migratory landbirds in Baja California has been little studied, yet the nonbreeding season is of critical importance in the life cycle of any bird. We used mist netting to quantify the relative abundance and demographic indices of six species of landbirds wintering in riparian habitat at two sites in Baja California. In addition, we assessed their persistence at the sites through area searches for and recapture of individuals marked with a unique combination of color bands. From the winter of 2004–05 through the winter of 2006–07 we captured 561 individuals of the six species along the Río Santo Tomás and Río San Vicente. The most abundant species, the Hermit Thrush (Catharus guttatus), Yellow-rumped Warbler (Setophaga coronata), and Ruby-crowned Kinglet (Regulus calendula), together accounted for 83.1% of all net captures of target species. The sex ratios of the six target species were not significantly different from 1:1 except for the Yellow-rumped Warbler, of which we found significantly more males than females. Persistence beyond one day and annual rates of return of the color-banded target species were generally low and did not differ by sex.

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