From the Spring 2025 issue of Living Bird magazine. Subscribe now.
Long-term studies from rainforests in Central and South America have shown puzzling declines among forest birds in remote, intact habitats—the kinds of places where birds should be thriving. A new, landmark 27-year study published in the journal Science Advances adds a crucial piece to the puzzle, pointing to climate change impacts as a cause of tropical forest bird declines.
Jared Wolfe, an ornithologist at Michigan Tech, and colleagues analyzed monitoring data for bird species within intact tropical forests in Brazil, in relation to changes in precipitation and temperature. They found that hotter and drier conditions during dry seasons (typically from March to September) significantly reduced survival rates for 24 out of the 29 species they studied. For every 1.8°F increase in dry season temperature, bird survival dropped by 63% on average. The spectacular White-plumed Antbird, which follows army ant swarms in the forest understory, declined significantly year over year as temperatures increased.
More on Tropical Bird Declines
Reduced rainfall even in the dry seasons also had a negative effect on these birds. A 0.4-inch decrease in rainfall led to a 14% reduction in survival rates among tropical forest birds in the study. These super dry conditions, the authors suggest, negatively affect understory insect populations that these birds rely on.
“These findings challenge the assumption that intact tropical rainforests are resilient to climate change. These birds serve as sentinels of climate change and broader disruptions to the whole ecosystem that we find inside these rainforests,” said Wolfe in a press release issued by Michigan Tech. “This study signals an emerging crisis for birds in one of the world’s most biodiverse regions.”
