Bird communities of natural and modified habitats in Panama

Only a small proportion of land can realistically be protected as nature re serves and thus conservation efforts also must focus on the ecological valu e of agroecosystems and developed areas surrounding nature reserves. In thi s study, avian communities were surveyed in 11 habitat types in central Pan ama, across a gradient from extensive forest to intensive agricultural land uses, to examine patterns of species richness and abundance and community composition. Wooded habitats, including extensive and fragmented forests, s hade coffer plantations, and residential areas supported the most species a nd individuals. Nearctic-Neotropical migratory species were most numerous i n lowland forest fragments, shade coffee, and residential areas. Introduced Pinus caribbea and sugar cane plantations supported the fewest species com pared to all other habitats. Cattle pastures left fallow for less than two years supported more than twice as many total species as actively grazed pa stures, such that species richness in fallow pastures was similar to that f ound in wooded habitats. Community similarities were relatively low among a ll habitat types (none exceeding the observed 65% similarity between extens ive and fragmented lowland forests), bur communities in shade coffee and re sidential areas were 43% and 54% similar to lowland forest fragments, respe ctively. Fallow pastures and residential areas shared 60% of their species. Bird communities in shade coffee and residential areas were characterized by higher proportions of frugivorous and nectarivorous species than in nati ve forests. These same guilds also were better represented in fallow than i n grazed pastures. Raptors and piscivorous species were most prevalent in c attle pastures and rice fields. These results, though based upon only speci es richness and abundance, demonstrate that many human-altered habitats hav e potential ecological value for birds, and conservation efforts in tropica l areas should focus greater attention on enhancement of agricultural and d eveloped lands as wildlife habitat. To understand the true conservation val ue of these modified lands will require examination not only of numbers but also of the types of species supported by these habitats, their reproducti ve output and survival rates.