Science

Nearly half of the world's birds are on the decline, which experts say is a serious threat to ecosystems

Birds are all around us, every day, and they play a crucial role in the health of our planet. But in the past 50 years nearly three billion birds have disappeared across North America and the European Union alone. And experts are worried that it could be a bigger sign about the health of our ecosystems.

BirdLife's State of the World's Birds 2022 report calls it a 'biodiversity crisis'

A Canada Jay is pictured in Algonquin Park, Ont. While populations are stable, new research has shown the species may be facing challenges due to climate change. (Submitted by Bill Longo)

It might be one early morning, after a particularly long, dark and snowy winter, that you first hear it: The call of a robin. A signal of spring.

Or it might be a walk through a park or forest where you hear a particular bird call and look up, hoping to identify it.

Birds are all around us, every day, and they play a crucial role in the health of our planet.

But in the past 50 years nearly three billion birds have disappeared across North America and the European Union alone, a recent report noted.  And experts are worried that it could be a bigger sign about the health of our ecosystems.

While it's been known for quite some time that the planet's birds are in danger, it was highlighted again by the recent BirdLife's State of the World's Birds 2022 report, something that they call a "biodiversity crisis." It also notes that 49 per cent of the planet's birds are in decline.

"In the 2018 report only 40 per cent of the bird species were found to be in decline. So in four years, we've had this huge jump in the number of birds that are at risk," said Sam Knight, a program manager at the Nature Conservancy of Canada.

"And they've shown that one in eight are actually threatened with extinction. So it's really concerning that in such a small time period this is what's happened, and the pressures these birds are facing, and biodiversity overall."

"I study birds, I love birds and I'm really concerned that I won't be able to go out for a walk and just hear birdsong in the same way," Knight said. "It's such a great mental health benefit to have these birds and species around; you don't even have to be a bird watcher, I don't think, to really appreciate what birds add to our lives."

Birds serve as pollinators, predators, seed dispersers, scavengers and, as the report noted, "ecosystem engineers." Because they are mobile, they traverse vast distances, linking different ecosystems. 

And their losses are considerable. 

WATCH | How climate change is affecting migratory patterns for birds:

Climate change altering migratory paths for some birds, researchers say

1 year ago
Duration 2:28
Researchers say they’re seeing the impact of climate change through the changing migratory patterns of birds.

The International Union for Conservation of Nature's (IUCN) Red List of Threatened Species has found that 1,409 bird species are considered threatened; 755 are vulnerable; 423 are endangered and 231 are critically endangered. 

And since the year 1500, at least 187 species of birds have gone extinct, mainly those found on islands.

Why is this happening?

The threats to our feathered friends are numerous, ranging from agriculture, logging, invasive species and hunting, to birds flying into homes and buildings, and climate change, only to name a few. And our furry cat companions are a big one, with an estimated 100 million to 350 million birds being killed across Canada each year by outdoor felines, according to a 2013 study.

"Invasive species are another huge threat to birds, and cats are the most invasive species, or the most threatening invasive species that we have in North America," Knight said. "There's no doubt that habitat loss is the biggest threat, but it's really hard to measure what habitat loss looks like when it comes to birds because they move, but cats … that is the biggest number of deaths that we can calculate in North America."

A hatchling Piping Plover and its mother is seen on a beach. The species is considered endangered by the Committee on the Status of Endangered Wildlife in Canada. (Randy G. Lubischer/Shutterstock )

But she noted that there are some solutions available to cat owners who still may want their cat to enjoy some fresh air. 

"What we need to do is keep our cats on leashes and keep them tethered when they're outdoors, or in a catio or that kind of thing. So people can still have their cat, enjoy the outdoors, but not be taking out birds," she said.

When it comes to habitat loss, it's grassland birds and insectivores that are most vulnerable, in particular because of the loss of grasslands in place of agriculture, which, Knight said, is understandable since we need to feed people. 

"But we also have to kind of think about this balance of how we can also keep grasslands and restore grasslands. And that has knock-on effects on not just birds but other species," she said. "And one great thing that this report highlighted and reminded us is that birds are really good indicators of what's going on with other biodiversity."

The Florida Scrub Jay, seen here, is listed as vulnerable on the IUCN's Red List of Threatened Species. (Tommy Daynjer/Shutterstock)

And then there's climate change, which is throwing off the timing for some migrating insectivores, as warmer weather is starting earlier in the year, which means insects come out earlier as well.

By the time the birds arrive, most of the insects' numbers have been reduced.

Need for more protections, big and small

Earlier this month, Birds Canada — an international partner of BirdLife — officially launched its Key Biodiversity Areas (KBAs) in an aim to protect not only birds, but other species, such as insects, frogs and turtles, who are facing numerous threats.

These areas require strict criteria to be designated a KBA. At the moment there are roughly 75 in Canada, with 900 in progress or being evaluated, said Andrew Couturier, senior director of landscape science and conservation at Birds Canada, who was not involved in the recent report.

"The [BirdLife] analysis shows that one in eight [birds] are threatened with extinction. That obviously varies geographically. Canada's birds aren't doing nearly as badly as that. But we still have a lot of a lot of work to do here," said Couturier, who was a co-author of the 2019 report on The State of Canada's Birds.

This graph illustrates the state of Canada's birds in 2019. (Environment and Climate Change Canada)

No surprise to Couturier, the 2019 report found that grassland birds in the Prairies were most at risk.

"There's hardly any native grassland left in Prairie Canada, and that's always under threat to be converted to some other use such as row cropping," he said. "But we do have good partnerships with the cattle industry, because those lands are actually providing good habitat for grassland birds and they're actually able to coexist with ranching."

Couturier said there are ways to reverse the trend of the loss of habitats and bird species. These can include individual efforts, such as putting stickers on big windows around our homes and planting bird- and pollinator-friendly gardens. On a larger scale, efforts can include office buildings turning off their lights at night to avoid migrating birds from crashing into them, the development of further KBAs across the country, and better land-use management. 

And the report, which also outlines some of these steps, is something Couturier said he sees as positive.

"If you talk to people in the charitable sector, you know, there definitely is a fatigue associated with depressing news all the time, when you're working so hard to try and make a difference," he said. "And then you keep seeing things going down and you wonder what else can we do? What can we do better to reverse this problem?"

But, he notes, "There are signs of hope."

ABOUT THE AUTHOR

Nicole Mortillaro

Senior reporter, science

Based in Toronto, Nicole covers all things science for CBC News. As an amateur astronomer, Nicole can be found looking up at the night sky appreciating the marvels of our universe. She is the editor of the Journal of the Royal Astronomical Society of Canada and the author of several books. In 2021, she won the Kavli Science Journalism Award from the American Association for the Advancement of Science for a Quirks and Quarks audio special on the history and future of Black people in science. You can send her story ideas at Nicole.Mortillaro@cbc.ca.

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