Climate change aggravates bird mortality in pristine tropical forests

Stable understory microclimates within undisturbed rainforests are
commonly regarded as refugia against climate change. Yet, this assertion
has rarely been tested, and contrasts with pervasive population declines
observed for many bird species in Amazonian forests unaffected by
landscape change or direct exploitation. We tested if population
vulnerability of resident rainforest birds may stem from climatic effects,
particularly during dry seasons with elevated temperatures and reduced
rainfall. Data from 4264 individual bird captures collected over 27 years
reveal strong negative consequences of harsher dry-season conditions on
survival for 27 of 29 species; an increase of 1° C reduced the aggregate
survival of the understory bird community by 34%. These results link
climate change to demographic processes in the heart of Amazonian
rainforest, raising doubts about the capacity of pristine rainforests to
protect their unparalleled biodiversity under increasingly severe climate
change.