The composition of avian communities in remanescent woodlots in southern Brazil

Censuses of birds in remanescent tvoodlots of lJfOO } 250, and 21 ha on the subtropical Sao Paulo plateau in southeastern Brazil showed 202, 1^6, and 93 species of birds still present.Presumably all areas originally had about 230 species before forest cutting became widespread.Few species present in a small woodlots were absent from a larger one, so that the small woodlots added to bird preservation mainly by repeating species in a different area.The large and medium woodlots had much the same numbers of individuals per 100 h of observation, but the small woodlot had few individuals and hence did not show density compensation.Certain groups of birds and mammals ivere especially prone to extirpation in small woodlots: large fmgivores of the canopy (parrots, cotingids, monkeys, etc.), birds eating large insects on or near the ground (antbirds, woodcreepers), and small insectivores of forest bamboo thickets and other tangles.Frugivores were to some extent replaced by edge-living omnivores, ground-living doves, and by ground-living mammals (apparently leading to increases in oxcls) in small woodlots.Small birds eating small insects, on or near the ground became more abundant, although not more diverse., in small tvoodlots.Migrants, which here were mostly birds of the forest canopy and edges, were common in the medium-sized woodlot but not in the small owe.Edge-living species became more abundant or relatively more abundant in small woodlots.These changes cause small woodlots to become more like temperate zone forests in emphases on oscine birds of canopy and edge and on migrants, and in loss of fruit-eating binZs.Losses of large hawks and of birds of the forest understory may be due to low population numbers and, occasional extinctions in small areas.Losses of canopy frugivores and of hummingbirds, which fly easily between woodlots, are more likely due to loss of specific flowering or fruiting trees used at certain times of the year.The conservation of ecosystems has received less attention over the years than has the preservation of conspicuous species.The hope has rather been that, when by diligent effort one sets aside and protects a patch of habitat that is the home of one or several species