Nearly half of migratory species in decline as UN summit opens
A UN summit on migratory species opens in Brazil on Monday as scientists warn that the long journeys of whales, fish, birds and other animals are being disrupted by climate change and human activity – with risks for ecosystems, food supplies and coastal economies.
Issued on: 23/03/2026 - RFI
A blue whale raises its tail off the California coast, part of a species known for long-distance migration in search of food and breeding grounds. AP - Nick Ut
Cop15 brings together governments to protect animals that move across borders and oceans.
The latest State of the World’s Migratory Species report – first published in 2024 and updated ahead of this summit – found that 49 percent of migratory species populations are now in decline, up from 44 percent two years earlier.
Around 24 percent face extinction globally.
Many of these animals travel long distances to find food or places to reproduce. Like humans, they move to find better living conditions, with food as the main driver.
One of the most striking examples takes place off southern Africa. A bloom of plankton attracts billions of sardines, which form huge shoals stretching for kilometres.
These shoals draw predators such as penguins, sharks and whales in a spectacle sometimes described as “the beating heart of the ocean”.
Whales are among the biggest travellers. Grey whales in the North Pacific migrate to warmer waters to reproduce.
The record belongs to a female called Varvara, who travelled more than 22,000 kilometres in six months between the Russian Arctic and Mexico at an average speed of six kilometres an hour.
But these long journeys are becoming harder.
Cop15 brings together governments to protect animals that move across borders and oceans.
The latest State of the World’s Migratory Species report – first published in 2024 and updated ahead of this summit – found that 49 percent of migratory species populations are now in decline, up from 44 percent two years earlier.
Around 24 percent face extinction globally.
Many of these animals travel long distances to find food or places to reproduce. Like humans, they move to find better living conditions, with food as the main driver.
One of the most striking examples takes place off southern Africa. A bloom of plankton attracts billions of sardines, which form huge shoals stretching for kilometres.
These shoals draw predators such as penguins, sharks and whales in a spectacle sometimes described as “the beating heart of the ocean”.
Whales are among the biggest travellers. Grey whales in the North Pacific migrate to warmer waters to reproduce.
The record belongs to a female called Varvara, who travelled more than 22,000 kilometres in six months between the Russian Arctic and Mexico at an average speed of six kilometres an hour.
But these long journeys are becoming harder.
Snowy egrets gather in Brazil’s Pantanal, an important stopover for migratory birds, as scientists warn that climate change and human activity are disrupting migration routes. AFP - PABLO PORCIUNCULA
Off course at sea
Fishing and noise from ships can throw whales off course.
“We see them going in circles, making squares instead of following their usual route,” Noémie Coulon, a researcher at the University of Montpellier, told RFI.
“The animals will eventually find their way, but they will have used more energy than if they had not been disturbed.”
Climate change is also altering migration. Warmer waters are pushing marine species towards the poles in search of cooler conditions.
“Marine animals are moving around 70 kilometres every 10 years towards the poles,” Coulon said.
“What we are seeing today is not just a change in temperature, but a reorganisation of marine ecosystems.”
Some species are also moving deeper into the ocean, by about seven metres every 10 years, to avoid human activity near the coast.
Pressure on survival
That shift is not without consequences. It is already affecting how species reproduce.
“There is a very strong relationship between water temperature and the time it takes for embryos to develop,” Coulon said, adding that at greater depths development is slower.
Since these species already have very slow life cycles, she said, it becomes much harder to renew populations.
The effects are also felt by people.
“Changes in the migration of these animals can affect cities and countries that depend mainly on the sea for their protein supply,” Coulon said. If a species moves from one country’s waters to another’s over time, “it can create tensions”.
The pressure is not limited to the oceans. The Hudsonian godwit, a shorebird that travels about 30,000 kilometres each year between the Arctic and South America, has seen its population fall by 95 percent in four decades.
Scientists say the bird depends on reliable food sources along its route, but those conditions are becoming less predictable.
“They need really predictable, abundant food resources at every step of the journey,” Nathan Senner, an ecologist at the University of Massachusetts Amherst, told the French news agency AFP.
He said the birds are now migrating later than before. Something “has either disrupted the cues that they use to time their migrations or their ability to successfully and rapidly prepare for the migration”.
A Hudsonian godwit, one of the world’s great migratory birds, whose journey is becoming harder as changing conditions disrupt its route. AFP - LUKE SEITZ
Senner added: “I think that is emblematic of lots of species, that most species can respond to one kind of change, but not a whole bunch of them all at the same time."
Other species proposed for protection at this week's summit include the snowy owl, the striped hyena and the hammerhead shark.
Amy Fraenkel, executive secretary of the Convention on the Conservation of Migratory Species (CMS), said the situation was “particularly alarming” for fish, with 97 percent of listed species threatened with extinction.
Declining numbers
Sharks and rays have seen their populations decline by about half since 1970. Freshwater migratory fish have been hit even harder, with monitored populations dropping by an average of 81 percent between 1970 and 2020.
Scientists say barriers such as dams are disrupting migration routes, preventing species from reaching feeding and breeding grounds.
Recent figures also show that 26 migratory species have moved into higher extinction-risk categories, including 18 birds. At the same time, seven species have improved, among them the saiga antelope, the scimitar-horned oryx and the Mediterranean monk seal.
Some conservation groups argue that protecting these species could also help tackle climate change.
The International Fund for Animal Welfare (IFAW), an animal protection group, points to research showing that dugongs play a key role in seagrass ecosystems.
Where they are present, carbon capture more than doubles, while the amount stored in sediments nearly triples.
“Protecting dugongs isn’t just about saving a species,” Catherine Bell, IFAW’s director of international policy, said.
“Where dugongs thrive, seagrass meadows flourish, and these ecosystems become even more powerful carbon sinks when dugongs are present.”
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