PARENT SESSION
Contributed Oral Session 18: Avian Communities and Populations
Monday, August 8, 8:00 AM - 11:30 AM, Meeting Room 524 C, Level 5, Palais des congrès de Montréal
Environmental correlates of bird species richness in a Neotropical landscape.
Rompre, Ghislain *,1, Robinson, Douglas2, Angehr, George3, Desrochers, Andre 1, 1 Universite Laval, Quebec, Quebec, Canada2 Oregon State University, Corvallis, Oregon, U.S.A.3 Smithsonian Tropical Research Institute, Panama City, Panama
ABSTRACT- A fundamental observation from ecology is that species are not distributed uniformly. Local species richness is influenced by many factors including environmental and anthropogenic ones. In Central Panama, bird species richness is very high, including nearly 200 forest-specialist species in an area of 60 x 25 km. Local levels of richness increase three-fold from the Pacific slope forests northward to the Caribbean slope forests. We mapped the distributions of all forest-dwelling bird species in all major forest reserves as well as many terrestrial fragments, totaling 57 different sites. We then asked what major environmental factors explain the strong increase in richness across such a relatively short distance on the isthmus. Species richness was positively related to annual rainfall, which was in turn positively related to distance to Pacific Ocean. Caribbean coastal forests receive more than twice as much rain per year as Pacific coastal forests. Area or fragment size, as expected, was also a positive correlate of species richness. But multiple regression shows that rainfall is a strong predictor of species richness when effects of habitat area are held constant. Small forest patches usually lack large fractions of the forest bird community and host only common, widely distributed species. Forest type, altitude, and topography also influence species richness. Richness also declines as time since isolation of fragments increases. Overall, the best models explaining bird species richness across this landscape include area and rainfall. These basic ecological data and analyses can be used to predict which sites are most likely to lose the most species as this region undergoes rapid economic development and experiences high rates of forest loss. Sites with more rainfall, greater topographic complexity, greater range of altitude, and more area are most likely to lose the most species.
Key words: bird species richness, distribution patterns, Central Panama, fragmentation