Meeting Abstract

P3.23  Tuesday, Jan. 6  Conservation ecology and social organization of the White-breasted Thrasher on St. Lucia MORTENSEN, J.L*; CURRY, R.L; Villanova University; Villanova University jennifer.mortensen@villanova.edu

The White-breasted Thrasher Ramphocinclus brachyurus is an endangered songbird endemic to the islands of St. Lucia and Martinique. Research in 2002-2004 established that the population comprises ca. 600 breeding pairs, 80% of which inhabit dry forest along the east coast of St. Lucia in two subpopulations. This work also revealed that the thrasher is a facultative cooperative breeder. The Praslin subpopulation is now facing an immediate threat: a resort under construction will destroy or fragment habitat containing up to 35% of the global thrasher population. Here we examine the effects of habitat loss associated with resort construction on White-breasted Thrasher reproductive success and social ecology. Mayfield nest success estimates did not differ between the pre (2002-04) and post-disturbance (2006-07) periods. From 2006 to 2007, nest success remained the same within fragments (27 fragments, 0.02-20 ha) and decreased in the resort nature reserve (26 ha plot bordering contiguous forest); edge nests were more successful than those in the interior. Group size and the proportion of groups cooperatively breeding increased significantly from 2002-04 to 2006-07, though we did not see any evidence of displaced birds joining previously established territories, as was predicted. This research advances understanding of how indirect mechanisms may magnify overall impacts of habitat loss, determines the degree of site fidelity of thrashers living in fragments on the development site and the effects of fragments on their tendency to maintain territories and group stability, and will influence future decisions about habitat protection on St. Lucia.