SONGBIRD USE OF GALLERY WOODLANDS IN RECENTLY CLEARED AND OLDER SETTLED LANDSCAPES OF THE SELVA-LACANDONA, CHIAPAS, MEXICO

Many regions of Central America have undergone wide-scale habitat chan ge as land has been converted for cultivation or grazing. Clearing for agriculture often leaves a variety of regenerating and remnant patche s of wooded vegetation. Of particular importance is arroyo vegetation, or strips of trees or tall shrubs growing along streams. Although it is widely, acknowledged that tropical arroyo vegetation supports high densities of birds as avian habitat it remains poorly studied. We used point counts to study populations of migrant and resident songbirds i n the arroyo vegetation of settled areas of the Selva Lacandona adjace nt to the Montes Azules Biosphere Reserve of southeastern Mexico. Two study areas were established on lands that had been cleared and settle d 20-35 and 10 years previously. Our objectives were to assess the val ue of arroyo vegetation to the conservation of avian species diversity and abundance in agricultural landscapes and to compare the compositi on and abundance of songbirds in cleared areas settled at different ti mes over a 35-year period. Arroyo vegetation had a wide diversity of s ongbird species that, in overall terms differed little between those l andscapes cleared recently and those cleared up to 35 years previously . In both areas we found a high abundance of habitat generalists and a smaller number of forest-dependent species, particularly migrants. Lo ss of forest specialists occurs rapidly, with little further loss as t he arroyos become increasingly isolated. Our data also suggest that bi rds do not crowd into limited habitat as the surrounding vegetation is eliminated implying that the overall carrying capacity of the agricul tural landscape is greatly enhanced as larger areas of arroyo vegetati on are protected. Protection of arroyo vegetation will increase the di versity of birds living in agricultural areas and can be achieved simp ly by expanding upon land-use practices currently in use.