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Rising global temperatures linked to bird population decline in remote areas

A team of environmental scientists from the Instituto Nacional de Pesquisas da Amazônia, Michigan Technologic University and the University of Oregon has found a link between rising global temperatures and the decline in bird populations in remote areas around the world. In their study in the journal Science Advances, the group tracked birds living in extremely remote forested areas and compared their findings against detailed climate data.

As human populations have grown over the centuries, the population of most other animals has decreased—this has been especially pronounced with birds. Prior research has shown that bird populations have been reduced virtually everywhere—even in remote places seemingly untouched by human encroachment.

Over the past two decades, researchers working in remote parts of the Amazon, for example, have found bird populations falling steadily, with some even going extinct. For many years, scientists have been baffled by the lack of a clear cause. In this new effort, the research team, working mostly in Brazil, has found a correlation between increasing global temperatures and declines in bird populations.

The work involved tracing bird population statistics compiled by other researchers working on the Biological Dynamics of Forest Fragments Project in Brazil over several decades, and comparing those numbers with climate data collected for the area covering the same time period.

The researchers found that as temperatures in the area rose, changes occurred to a variety of plants and animals, resulting in an environment less supportive of birds. The new drier seasons, they found, have reduced survivability in 24 of 29 bird species in affected areas. They also found that a change in average global temperatures of just 1°C led to a reduced average survivability of birds in the area by 63%.

They note that birds are particularly sensitive to changes in their environment because they build nests, lay eggs and forage for food for their young. Slight changes in temperature can lead to timing problems for birds—if the food they seek for their young, for example, has come and gone by the time their young hatch, the nestlings will starve, leading to a steadily declining population over time.