The effect of native human agricultural systems on avian diversity in neotropical forests is poorly understood. In 1996 and 1997 I conducted a study comparing landscape heterogeneity and raptor species diversity in pristine rain forests and forests affected by shifting cultivation of Indian peoples in northeastern Honduras. Raptors were surveyed in 1-km2 survey plots from points above the forest canopy. Landscape heterogeneity was calculated after mapping five natural and anthropogenic habitat types in these same plots. Differences in the diurnal raptor community were then compared along a gradient of landscape heterogeneity. Raptor species diversity, richness, and density all increased as a result of increasing levels of shifting cultivation, and species composition likewise differed among landscape heterogeneity classes. I found landscape heterogeneity to be the most important habitat variable in explaining changes in raptor species diversity. Although shifting cultivation at its current extent appeared to be increasing raptor species diversity on the study area, further increases in deforestation would likely lead to a loss of many interior forest species and an eventual decline in raptor species diversity in deforested areas.
This chapter reports the findings of a survey of the avifauna of the central Rio Platano Biosphere Reserve (RPBR) in the Mosquitia region of northeastern Honduras. I recorded a total of 248 species January – June 1996 and 1997 using both above-canopy and ground-based methods, including three species new to the avifauna of Honduras. Of this total, 191 species are considered “core” inhabitants of upland forest habitats. I also predict that an additional 103 species may also be found in the RBPR (based on published observations, ranges and habitat affiliations), bringing the estimate of the total bird species to 351.
The avifauna of the RPBR shares many similarities with two well-known avifaunas of similar lowland forest sites in Central America, La Selva, Costa Rica, and Barro Colorado Island, Panama, but is different in two regards. First, the RPBR has fewer species adapted to anthropogenic habitats and, second, has fewer species overall, due mostly to its greater distance from the species rich pool of South America. However, the avifauna of the RPBR is distinctive because it has species representative of North, South, and Central America.
In 64 hours of above-canopy surveys I observed 1075 individuals of 116 species. An additional 132 species were detected during incidental observations from the ground. During canopy surveys, significantly more species and individuals were detected in the canopy and air than in understory, shrub, and ground strata. These results suggest that canopy-based surveys may be a valuable addition to more standard ground-based survey techniques in estimating the numbers of species and their abundances in neotropical lowland rain forests.