A study of birds in The AmazonResearch in the rainforest suggests that birds are becoming smaller physically over the last 40 years.
“This study is an example of climate change — human actions globally — affecting a fundamental thing such as the size and shape of these birds in the middle of the Amazon, the symbol of terrestrial biodiversity,” ecologist Vitek Jirinec told NBC News. Jirinec was the lead author of this study. published in the journal Science AdvancesOn Friday.
This paper examined the weights and measurements of 77 bird species over the past 30 years. Nearly every bird species has become lighter with time. Most species have lost about 2% per decade on average. That is quite significant considering the small size of these creatures.
“These birds don’t vary that much in size,” co-author Philip Stouffer, a professor of conservation biology at Louisiana State University, said in a releaseFrom the institution. “They are fairly fine-tuned, so when everyone in the population is a couple of grams smaller, it’s significant.”
While birds’ bodies have gotten smaller over time, their wings have gotten longer. Researchers believe that this is an adaptation to higher temperatures. Birds with longer wings are more efficient at moving around and use less energy.
“The thing that is the most striking about this to me is that this is in the middle of the most intact tropical rainforest in the world,” Stouffer told NPR.
The researchers looked at nonmigratory birds ― birds that live within the confines of the rainforest. They found that the area they examined was not affected by deforestation and other forms of development. Climate was the only thing that had changed around them: Wet season have become wetter, while dry season have become dryer and both have seen their average temperature increase.
The researchers found that bird species living in higher parts of the forest ― as opposed to closer to the forest floor — saw the biggest changes in terms of body composition. Because they are more exposed to heat, this supports the theory that climate changes may be the reason. They’re also the species that fly the most, meaning that conserving energy while doing so would be the most important for them.
This isn’t the only study to suggest that climate change has played a role in animals getting smaller. This is a summary of the findings. 2019 study led by University of MichiganResearchers analyzed the sizes of 52 species migratory birds from North America between 1978 and 2016. They all had smaller bodies than in 1978 and 2016 with longer wings.
A study earlier in the year also found this. critically endangered North Atlantic right whalesOn average they are 3ft shorter than their 20-year-old counterparts. Scientists attributed this to stress caused by myriad human-related causes — among them anthropogenic climate change, which has forced the whales to swim farther north to reach their cold-water prey.