PARENT SESSION
Poster Session # 18: Avian Ecology.
Thursday, August 7 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.
Effects of habitat modification on the understory birds of southern Costa Rican countryside.
Ruiz-Gutierrez, Viviana2, Loarie, Scott*,1, Sekercioglu, Cagan1, Daily, Gretchen1, Ehrlich, Paul 1, 2 University of Costa Rica, Heredia, CR1 Stanford University, Stanford, CA, USA
ABSTRACT- We sampled 10,548 birds from 192 species with mist nets from the Las Cruces forest, small forest fragments, and coffee plantations around Las Cruces Biological Station in southern Costa Rica. Our objective was to understand the effects of forest fragmentation and land conversion on the diversity and composition of the local understory avifauna. We sampled both during dry (February through April) and wet (June through September) seasons in three different years between 1999 and 2003. We had 6929 captures in coffee plantations, 1935 captures in the Las Cruces forest, and 1584 captures in 3-5 ha forest fragments. The composition of the avifauna was significantly different between Las Cruces forest, fragments and coffee plantations. Understory insectivores were significantly more abundant and speciose in the Las Cruces forest, while granivores, omnivores, and northern migrants were significantly more common and speciose in small fragments and coffee plantations. Forest-dependent species were mostly absent from coffee plantations and were significantly under-represented in small fragments. The hotter, drier, and more volatile microclimatic conditions in small fragments, and especially in coffee plantations, were likely important factors in the absence of numerous forest bird species from these sites. Presence of a bird species in the agricultural matrix surrounding forest patches was the best determinant of its occurrence in the small forest fragments. Poor dispersal ability between forest patches was the most likely cause of the decline of many forest species, particularly in the superfamily Furnarioidea, from small fragments. Better integration of human-dominated ecosystems and small forest fragments into tropical conservation strategies can significantly increase the capacity of sub-optimal habitats to support native bird species.
Key words: neotropical conservation, understory birds, coffee plantations, fragmentation