Small Birds, With Long Wings: Even in the heart of the Amazon, birds have had to adapt to global warming.

Warmer temperatures have made these animals evolve, according to a new study conducted on 77 species of birds over the past 40 years, and a new study published Friday in the journal Science Advances.

Researchers hypothesize: With less heavy and larger wingspan, birds could fly more efficiently while expending less energy. Smaller fins that carry more weight require you to beat them faster, which creates more body heat.

According to the study, greater pressure on food resources may have affected their weight as well.

“All of this is happening away from direct human disturbance (such as deforestation), in the middle of the world’s largest rainforest,” study lead author Vitek Jirinek told AFP. According to him, these results thus underscore the general impact of climate change caused by humans.

He and his colleagues analyzed data collected on more than 10,000 non-migratory birds caught, measured and released over an area of ​​about 40 kilometers in Brazil.

They also used climate models that allowed them to determine that temperatures increased by 1 °C during the rainy season, and 1.65 °C during the dry season since 1966.

All species studied were found to have lower body mass than in 1980. And most species lost an average of 2% body mass each decade.

In fact, a bird species that averaged 30 grams in the 1980s weighs about 27.6 grams today.

“These birds do not vary greatly in size,” study co-author Philipp Stauffer said in a press release. “So when an entire population loses a few grams, it’s important.”

Birds that walked the most were most affected by this weight loss compared to those that lived closer to the ground. However, the former are exposed to hotter and drier conditions.

In addition, according to the study, 61 species also showed an increase in the length of their wings.

Its authors believe that a similar effect is likely to affect other species living elsewhere in the world. “It certainly happens everywhere, and maybe not just in birds,” insisted Philipp Stauffer.