This is Scientific American's 60-Second Science.

I'm Shayla Farzon.

Climate change is affecting animals in a lot of different ways.

But scientists have noticed a common trend across a variety of species.

They're getting smaller, as in physically smaller in size.

But why?

And what could this mean?

Scientists have observed this phenomenon in very different animal species, from wild

sheep to wood rats.

But it's especially well-documented in North American songbirds.

In 2019, researchers at the University of Michigan published a data set of more than 70,000

birds that died after hitting windows in Chicago.

The data showed that the body sizes for dozens of species had actually shrunk over the past

40 years.

But when Justin Baldwin, a graduate student at Washington University in St. Louis, took

a closer look at the data, something stood out.

The question was, why were some bird species shrinking faster than others?

Baldwin and his colleagues had a feeling that bird behavior might be playing a role.

In birds, species with bigger brains tend to be smarter, and can change their behavior

based on their environment.

That means they might be able to buffer themselves from increasing temperatures, says Carlos

Batero, an assistant professor of biology at Washington University and the studies co-author.

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