Local extinctions of terrestrial insectivorous birds in a fragmented landscape near Manaus, Brazil

We examined the distributions of nine species of terrestrial insectivorous birds in 4- to 14-year old rainforest fragments north of Manaus, Brazil. We surveyed 11 fragments of 1. 10, ha, 95 ha of secondary vegetation, and nin e continuous forest plots (controls) of 1-100 ha. We augmented standard spo t-mapping with extensive playback surveys. The fragments had been sampled w ith mist nets before isolation, so our results could be compared with the p re-isolation distribution. For the nine species, there were 55 cases of loc al extinction in the 11 fragments between about 1 year after isolation and the time of our surveys. This corresponds to 74% extinction of the local po pulations in fragments. These extinctions occurred despite the second-growt h connection of some fragments to continuous forest as little as 70 m away. Three apparent colonization events by species non detected before isolatio n also occurred, but these may also reflect inadequate sampling before isol ation. Our comparison of fragments and control plots, but fragments had few er species than control plots of equal size. In a fragmented Amazonian land scape, the full suite of terrestrial insectivores would persist in the shor t term only in large fragments (>100ha), although much larger areas are pro bably necessary for the long-term persistence of their populations.