Data from: Low species turnover of upland Amazonian birds in the absence of physical barriers

Aim: One of the oldest and most powerful ways for ecologists to explain
distinct biological communities is to invoke underlying environmental
differences. But in hyper-diverse systems, which often display high
species richness and low species abundance, these sorts of community
comparisons are especially challenging. The classic view for Amazonian
birds posits that riverine barriers and habitat specialization determine
local and regional community composition. We test the tacit, complementary
assumption that similar bird communities should therefore permeate uniform
habitat between major rivers, regardless of distance. Location: Upland
(terra firme) rainforests of central Amazonia. Results: In all, we
detected 244 forest-dependent birds, with an average of 190 species (78%)
per plot. Species turnover was negligible, no unique indicator species
were found among plot pairs, and all documented species were already known
from a complete inventory at one of the three sites. Main conclusions: Our
study corroborates the classic biogeographical pattern and suggests that
turnover contributes little to regional avian diversity within upland
forests. Using a grain size of 100 ha, this implies that upland birds
perceive the environment as uniform, at least over distances of ~60 km.
Therefore, to maximize both local species richness and population
persistence, our findings support the conservation of very large tracts of
upland rainforest. Our analyses also revealed that the avifauna at Reserva
Ducke, encroached by urban sprawl from the city of Manaus, shows the
hallmarks of a disturbed community, with fewer vulnerable insectivores.
This defaunation signals that even an enormous preserve (10 × 10 km) in
lowland Amazonia is not insulated from anthropogenic degradation within
the surrounding landscape.