JOHN YANG: As the climate crisis worsens so does pressure on wildlife.

New research indicates that the population of nearly half of all animal species is declining.

And as Ali Rogin reports, among the most affected are birds.

ALI ROGIN: If you're accustomed to waking up to the sound of them chirping or watching them flock to the feeder outside, you might not realize it, but birds are in trouble.

The number of birds in North America has declined by 3 billion in the last 50 years.

That decline has hit some species of the animal harder than others with birds living in Canadian and American grassland habitats, experiencing the biggest drops in population.

Joining me now is Brooke Bateman, Director of Climate Science at the National Audubon Society.

Brooke, thank you so much for joining us.

Two-thirds of North American bird species are teetering on the edge of extinction.

Why is this?

What environmental factors lead to this?

BROOKE BATEMAN, Director of Climate Science, National Audubon Society: Yeah, so we've lost 30 percent of our births since 1970.

And a lot of the changes that we've seen across the North America are due to human changes in the landscape, such as loss of forests, conversion of grasslands, to agriculture.

So we've seen a lot of habitat loss, it's really affected the birds in North America where they have less habitat than they used to back in 1970 and prior to that.

ALI ROGIN: And how much of this is attributable to climate change?

BROOKE BATEMAN: So we are already seeing effects of climate change.

And what we're actually seeing is sort of these two effects working together against species.

So the loss of habitat combined with climate change, is making it trickier for birds to find places that have ideal conditions for them to survive.

So, we're already seeing birds move because of climate change and trying to find new locations to move into.

And that's tricky when there's not a lot of habitat because things have been altered on the landscape from what they've been used to.

ALI ROGIN: And tell us a little bit about the role that birds play in the ecosystem and what might happen.

What are the detrimental effects if their populations continued to decline?

BROOKE BATEMAN: Yeah, birds are really integral for the ecosystem.

At Audubon, we say birds tell us because birds tell us what's happening in the ecosystem.

And they really are tied to that the changes that we're seeing.

And so birds are really important for things like insect control, they really help our crops, including our coffee crops that have insects, they come help and by eating the insects, they help those crops survive.

They also keep away some of our invasive species, the insects like emerald ash borers.

They're really important for pollination.

So some of the key things that we need from pollination brings us our vegetables, and our fruits.

And birds are key for that along with insects.

And they also do other things.

So blue jays, for example, are one of our, what we call ecosystem engineers, because when they pull acorns off the ground from Oak trees, they can actually move those hundreds of miles and build forests.

So they're important for the movement and the growth of new forests.

So birds just do a ton for us.

And if we didn't have them, we lose a lot of those ecosystem services.

ALI ROGIN: Talk to us about the efforts on the federal level to conserve the species.

BROOKE BATEMAN: Yeah, so the Migratory Bird Treaty Act is an act that helps protect migratory birds and protects them.

And so that's been a really important act that has helped birds and keep them protected within North America, as well as the Endangered Species Act for some of our species that are endangered to really make sure that they have the safety that they need out in the places that they live.

So those are two really important federal policies that that help protect birds.

ALI ROGIN: And I know a lot of the efforts right now are about keeping birds off that Endangered Species Act list.

But what additional steps would you like to see in terms of preserving and renewing these species populations?

BROOKE BATEMAN: Yeah, so I think one of the biggest things that we can do is try to help bring back certain habitats and restoration efforts are really going to be key here, but there are things that you can do even in your own backyard.

So one of the things that I think is the most exciting and promising is planting native plants and reducing the amount of grass that you have in your backyard and putting more native plant species, because that will provide habitat for birds and food for birds.

And also it actually has a wonderful side effect that plants actually store carbon in their matter.

And so that helps pull carbon out of the atmosphere carbon dioxide, so it also helps with climate change.

So it's kind of a win-win, to rely on these ecosystem native plants and habitats that will benefit birds and help stabilize the climate.

ALI ROGIN: And the Audubon Society has been doing a lot to get individuals involved as well.

I mean, the Audubon Society has been studying birds since it was founded about a century ago.

But now you have a lot of kind of open source resources for folks, including the Climate Watch program.

Tell us about that, and how it's helping advance our understanding of birds.

BROOKE BATEMAN: Yeah.

So at Audubon, we study how climate change affects birds, we put out a report in 2019 that showed that two-thirds of birds in North America are extinct -- at risk of extinction because of climate change.

And so we really wanted to track how that was happening on the ground in real time in Climate Watch.

This is having volunteers across the country, go out and count birds and look for birds.

And what we're doing is scientists were studying and looking at how these birds are actually shifting where they live because of climate change.

And so we're looking at climate change as it's happening.

Climate change is not a far off problem that's happening only with polar bears, we're actually finding that the birds are changing where they occur because of climate change.

And that's because of the Climate Watch program.

It's one of the ways that we're able to understand that climate change is already affecting the birds that we love in our backyards.

ALI ROGIN: And of course, we're talking about all of these species that are endangered.

But there are some bright spots, it seems in some of these recent reports, including waterfowl populations have actually been on the rise.

And that seems to be kind of ironically, thanks to the efforts of hunters and fishermen.

I'm wondering if you can talk about that and any other notable grassroots efforts to preserve certain species?

BROOKE BATEMAN: Yeah, I think waterbirds are a wonderful example of how when we take conservation actions into our own hands and put some funding into it, we can really make a big difference.

And the funding that's been coming in through hunters, as well as duck stamps, which hunters needs to acquire before they hunt, but anybody can buy a duck stamp, that money goes back into the system and the Fish and Wildlife Service helps establish habitats and do conservation efforts that have helped waterbirds do so well.

So I think it's a great model to show that if we know what we need to do, we can make a big difference.

Another great example is the Raptors.

So our eagles and our bigger hawks, those birds were in decline because of a pesticide called DDT.

And again, there were big efforts to kind of remove that pesticide from the system.

And now those birds that 50 years later have bounced back and we can see bald eagles kind of all over the U.S. now where we used to not be able to.

So, it just shows that if you know what to do, and you take action, you can make a big difference.

ALI ROGIN: Brooke Bateman, Director of Climate Science at the National Audubon Society.

Thank you so much for joining us.

BROOKE BATEMAN: Thank you for having me.