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Birds in the Amazon have been shrinking. Here's why scientists think it's happening

AILSA CHANG, HOST:

In recent years, scientists found something strange was happening among sensitive bird species in the Brazilian Amazon. Not only were the birds declining in number, but their bodies were shrinking in size.

VITEK JIRINEC: But then we found that size is not only shrinking for those sensitive species. It was declining for everyone.

MARY LOUISE KELLY, HOST:

That is Vitek Jirinec of Louisiana State University. He and his colleagues have now found that over the past four decades, 77 different species of Amazonian birds have been getting slightly smaller on average. Philip Stouffer was Jirinec's advisor at Louisiana State.

PHILIP STOUFFER: 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.

CHANG: Now, if you're wondering why that is, well, the short answer may be climate change. Over the 40-year study period, the rainforest has gotten warmer.

KELLY: That's right. And a smaller bird would shed heat more efficiently. It has more surface area in relation to its volume. Now, here's an example that might be a little easier to relate to.

BRIAN WEEKS: You could imagine lots of little ice cubes in a glass of water, as opposed to one big ice cube, and the little ice cubes melt faster because smaller things have larger surface area-to-volume ratios, so they exchange heat more quickly.

CHANG: Brian Weeks of the University of Michigan didn't work on this particular study, but he did study the size of more than 50 species of migratory birds in North America a few years back. And he found the same thing. Nearly all of them were shrinking decade by decade.

KELLY: The two studies reinforce the idea that birds all over the planet, migratory or not, may be changing shape due to a warming climate. Weeks says these sorts of changes should concern all of us.

WEEKS: All around the world, people depend on natural systems. Intact natural systems provide more economic benefits to humanity than the entirety of the world's GDP, so they matter to you whether or not you know it.

CHANG: Vitek Jirinec of Louisiana State says the timing of his paper's publication could not be more fitting.

JIRINEC: Our study comes out on the same day as the conclusion of the U.N. Climate Change Conference in Glasgow. So those results really underscored the pervasive consequences of our actions for the planet.

CHANG: The study is out today in the journal Science Advances. Transcript provided by NPR, Copyright NPR.

Christopher Intagliata is an editor at All Things Considered, where he writes news and edits interviews with politicians, musicians, restaurant owners, scientists and many of the other voices heard on the air.

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SOMOS CONNECTICUT is an initiative from Connecticut Public, the state’s local NPR and PBS station, to elevate Latino stories and expand programming that uplifts and informs our Latino communities. Visit CTPublic.org/latino for more stories and resources. For updates, sign up for the SOMOS CONNECTICUT newsletter at ctpublic.org/newsletters.

SOMOS CONNECTICUT es una iniciativa de Connecticut Public, la emisora local de NPR y PBS del estado, que busca elevar nuestras historias latinas y expandir programación que alza y informa nuestras comunidades latinas locales. Visita CTPublic.org/latino para más reportajes y recursos. Para noticias, suscríbase a nuestro boletín informativo en ctpublic.org/newsletters.

The independent journalism and non-commercial programming you rely on every day is in danger.

If you’re reading this, you believe in trusted journalism and in learning without paywalls. You value access to educational content kids love and enriching cultural programming.

Now all of that is at risk.

Federal funding for public media is under threat and if it goes, the impact to our communities will be devastating.

Together, we can defend it. It’s time to protect what matters.

Your voice has protected public media before. Now, it’s needed again. Learn how you can protect the news and programming you depend on.