eWestern BirdsThe Quarterly Journal of Western Field Ornithologists
Vol. 44, No. 4
Western Field Ornithologists
Movements of the Mangrove Warbler in Baja California Sur
Cheryl L. Schweizer and Robert C. Whitmore
ABSTRACT: Mangrove forests are one of the most productive ecosystems in the world. Despite this, over half of the world’s mangroves have been lost through human activities. As suitable habitat declines, mangrove birds are forced into small isolated patches, exposing them to the dynamics of small populations. Our primary objective was to quantify local movement of Mangrove Warblers of the apparently sedentary subspecies Setophaga petechia castaneiceps, endemic to mangroves of Baja California Sur. In 2010, we captured and color-banded 108 breeding adult Mangrove Warblers at 16 sites, then surveyed all surrounding mangroves during the following winter and breeding seasons. We found no movement from one stand of mangroves to another, but we did find territory switching within a stand from winter to the breeding season. The rate of replacement of birds in a territory was high, suggesting that the proportion of floaters is high. We found no significant changes in population density by season or sex.