Sharjah24 – AFP: Even the wildest parts of the Amazon untouched by humanity are being impacted by climate change, according to new research.

Hotter, drier conditions over the past four decades are decreasing the body size of the rainforest's birds while increasing their wingspans, a study published in the journal Science Advances said Friday.

The changes are thought to be a response to nutritional and physiological challenges, especially during the June to November dry season.

"The biggest takeaway for me is that this is happening far from direct human disturbance, such as deforestation, in the heart of the world's biggest rainforest," Vitek Jirinec, an ecologist at the Integral Ecology Research Center and the paper's lead author told AFP.

"That is something to ponder on the last day of COP26," he added.

Jirinec and colleagues analyzed data collected on more than 15,000 birds that were caught, measured, weighed, and tagged over the course of 40 years of field work.

They found that nearly all the birds had become lighter since the 1980s.

Most species lost an average of two percent of body weight every decade, meaning a bird species that would have weighed 30 grams in the 1980s would now average 27.6 grams.

The data was not tied to a specific site but rather collected from a large range of the rainforest, meaning the phenomenon is ubiquitous.