Mercury (Hg) concentrations and their associated toxicological effects in terrestrial ecosystems of the Gulf of Mexico are largely unknown. Compounding this uncertainty, a large input of organic matter from the 2010 Deepwater Horizon oil spill may have altered Hg cycling and bioaccumulation dynamics. To test this idea, we quantified blood concentrations of total mercury (THg) in Seaside Sparrows ( Ammospiza maritima ) and Mars...

Insectivores of the tropical rainforest floor are consistently among the most vulnerable birds to forest clearing and fragmentation. Several hypotheses attempt to explain this pattern, including sensitivity to extreme microclimates found near forest borders, particularly brighter and warmer conditions. Importantly, this “microclimate hypothesis” has additional implications for intact forest under global climate change that cou...

How are rainforest birds faring in the Anthropocene? We use bird captures spanning > 35 years from 55 sites within a vast area of intact Amazonian rainforest to reveal reduced abundance of terrestrial and near‐ground insectivores in the absence of deforestation, edge effects or other direct anthropogenic landscape change. Because undisturbed forest includes far fewer terrestrial and near‐ground insectivores than it did histori...

The rainforests of the Amazon basin are being cut by humans at a rate >20,000 km 2 /year, leading to smaller and more isolated patches of forest, with remaining fragments often in the range of 1–100 ha. We analyzed samples of understory birds collected over 20 years from a standardized mist‐netting program in 1– to 100‐ha rainforest fragments in a dynamic Amazonian landscape near Manaus, Brazil. Across bird guilds, the conditi...

The impacts of potential linear barriers such as roads, highways, and power lines on rainforest fauna are poorly understood. In the central Brazilian Amazon, we compared the frequency of local movements (≤300 m long) of understory birds within intact forest and across a 30‐ to 40‐m‐wide road over a 2‐year period. Rainforest had regenerated along some road verges, to the extent that a nearly complete canopy was formed in some a...

We synthesized key findings from the Biological Dynamics of Forest Fragments Project, the world's largest and longest‐running experimental study of habitat fragmentation. Although initially designed to assess the influence of fragment area on Amazonian biotas, the project has yielded insights that go far beyond the original scope of the study. Results suggest that edge effects play a key role in fragment dynamics, that the mat...

Roads through tropical forest create linear disturbances that have unknown consequences for forest birds. We studied how a narrow, rarely used road through otherwise undisturbed Amazonian forest affected the movements and area requirements of understory birds that form mixed‐species flocks. Differences in road maintenance led to two distinct treatments along the same road. Trees along the “closed” road formed a partial canopy...

Forest fragmentation may negatively affect populations typically found within continuous forest tracts. Some effects, such as absence from small fragments, are obvious, but other effects may be subtle and easily overlooked. We evaluated the hypothesis that forest birds dwelling in fragments, where microclimatic conditions have been shown to be hotter and drier than in continuous forest, may be in poorer physiological condition...

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, and 100 ha, 95 ha of secondary vegetation, and nine continuous forest plots (controls) of 1–100 ha. We augmented standard spot‐mapping with extensive playback surveys. The fragments had been sampled with mist nets before isolation, so our results...