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Effects of Habitat Alteration on a Tropical Avian Forest Community

1985; Issue: 36 Linguagem: Inglês

10.2307/40168333

1941-2282

John H. Rappole, Eugene S. Morton,

Ecology and Vegetation Dynamics Studies

Individuals of a tropical forest avian community at a site near Catemaco in southern Veracruz were captured, banded, and observed during field work in the winters of 1973-1974 and 1974-1975. The site was revisited and resampled in November-December 1 980 and 1981. Vegetation on the site had been changed during the interim as a result of human activity, from mature forest to various forms of disturbed forest and second growth. Changes in avian populations associated with habitat alteration included drastic decreases in total numbers of forest-dwelling migrant and resident species and individuals on the site and changes in the behavior of individuals from territoriality to nomadism. We hypothesize that destruction of mature forest will cause declines in forest-dwelling tropical residents and wintering migrants that breed in temperate North America. RESUMEN. Durante un estudio de campo llevado a cabo en los inviernos 1 9731974 y 1974-1975, se capturaron, anillaron y observaron individuos de una comunidad de aves de un bosque tropical en una localidad cerca de Catemaco en el sur de Veracruz. El sitio fue visitado nuevamente y se volvieron a juntar muestras en noviembre-diciembre de 1 980 y de 1981. Como resultado de la actividad humana durante el interin, la vegetaci6n del sitio ha cambiado de bosque maduro a varios tipos de bosque alterado y vegetaci6n secundaria. Cambios en las poblaciones de aves, asociados con la alteraci6n del habitat, incluyeron disminuci6n drastica en el numero total de especies que habitan en el bosque, tanto residentes como migratorias, ya sea para cantidad de especies o de individuos; asi mismo hubo cambios en el comportamiento de individuos anteriormente territoriales, ahora n6mades. Nuestra hip6tesis es que la destrucci6n del bosque maduro causara reducciones en las especies tropicales residentes que habitan en el bosque, asi como en las aves migratorias que invernan en la regi6n pero que reproducen en regiones templadas de America del Norte. Habitats in many parts of the neotropics are being converted rapidly to agriculture (Myers 1980). The high conversion rates are cause for concern for the welfare of tropical resident avian species as well as migrants from Canada and the United States that winter in the Neotropics (Vogt 1970; Briggs and Criswell 1979; Terborgh 1980; Deis 1981). Here we report on the first study of changes in wintering bird populations at a tropical site converted from undisturbed mature forest to disturbed forest and second growth. We believe the results have important implications for our understanding of tropical avian ecology. Furthermore, the data may help resolve the question of relative suitability of mature versus disturbed forest habitats for forest-dwelling species. The birds wintering at the site were studied originally during winters (November-March) over a two year period from 1973 to 1975 (Ramos and Warner 1980; Rappole and Warner 1980). Five years later we returned to renew our studies and found that the site had been changed from primary tropical forest to various forms of undisturbed, isolated forest, disturbed forest, pasture, second growth, and edge. This change allowed us to compare our netting and observational results from the different sampling periods with regard to changes in the species composition of the community and social behavior of selected species. We were also able to obtain a measure of relative habitat suitability for these species before and after human disturbance. STUDY SITE AND METHODS The study area is located in the Tuxtla Mountains of southern Veracruz, Mexico, roughly 30 km northeast of the town of Catemaco. The climax vegetation for the lowlands of the region is selva alta perennifolia, or tall rainforest (Andrle 1964; Pennington and Sarukhan