Amazonian Birds Are Shrinking, Studies Show

In the past 40 years, birds in the Amazon rainforest have gotten significantly smaller, according to a study published in Science Advances. Scientists believe the change in body mass is correlated with climate change, as warming temperatures are affecting the available resources in the birds’ habitat.


All of the 77 bird species that researchers looked at had a lower mean mass than they did in the 1980s, and a third of the species had increased wing length. The decrease in the mass-to-wing ratio is correlated with warming temperatures, as scientists believe that longer wings and a lighter body consume less energy and therefore keep the birds cooler. The effects of climate change on seasons and water availability, such as a drier, hotter season, are correlated to the physical shifts in birds.

Other studies have found the same pattern in migratory birds, which have also been developing longer wings and lighter bodies.