Depending on the mosaic of habitats that is created, forest fragmentation can reduce the abundance and diversity of forest birds. Temperate deciduous forests in South America are rapidly being replaced by pine plantations, causing changes in habitats for both breeding and migrant birds. We examined differences in avian species richness and abundance in three areas: a reserve with continuous tracts of native forest, forest fragments and pine plantations. Four species were negatively affected by fragmentation, with their abundance declining from continuous forest to pine plantations. Fourteen species were not affected by fragmentation and eight had significantly increased abundance in pine plantations compared to continuous forest. Overall abundance in pooled and ground/understorey birds was higher in forest fragments and pine plantations compared to continuous forest. The abundance of granivorous species was higher in the pine plantations than in the forest reserve, but the abundance of insectivorous species was higher in the forest reserve and in forest fragments than in pine plantations. Thus, forest fragmentation affects birds differentially according to their feeding ecology.