Humans have altered the Earth so much that migratory animals are facing extinction

By Angela Dewan and Rachel Ramirez, CNN

(CNN) — Female leatherback turtles are among the world’s most intrepid creatures, making journeys as far as 10,000 miles after nesting to find food in far-away seas. They’ve been known to set off from tropical Southeast Asia up to the cold waters of Alaska, where jellyfish are abundant.

But travelling such a long way means encountering threats that can be fatal: fishing nets intended for other species, poachers, pollution and waters warmed by the climate crisis, which force the turtles to travel even further to find their prey.

These turtles are just one of hundreds of migratory species — those that make remarkable journeys each year across land, rivers and oceans — that are facing extinction because of human interference, according to a landmark UN agency report published Monday.

Of the 1,189 creatures listed by the Convention on the Conservation of Migratory Species of Wild Animals, or CMS, more than one in five are threatened.

They include species from all sorts of animal groups — whales, sharks, elephants, wild cats, raptors, birds and insects, among others.

Some 44% of those species listed are undergoing population declines, the report said. Most alarming is the state of the world’s migratory fish: Nearly all, 97%, of those listed are threatened with extinction.

The report is the first inventory to assess the status of migratory species and how they are trying to survive in a world dramatically changed by humans. It found the two biggest threats were overexploitation and loss of habitat because of human activity, such as clearing land for farming, roads and infrastructure. Those activities also fragment migratory species’ pathways, sometimes making it impossible for them to complete their journeys.

Around 58% of the monitored locations recognized as important for migratory species are facing what the CMS says are unsustainable levels of pressure from humans.

Climate change and pollution are also major threats. Warmer temperatures not only force some species to travel farther, but can also lead animals to move at different times of year. That can mean missing out on prey or a mate for breeding.

One particularly stark example is the narwhal. These mythical-looking sea creatures, famous for their spiralled tusks, spend summers in mostly ice-free coastal areas before migrating south into deeper Arctic waters.

However, as the oceans warm and annual sea ice expansion happens later and later, scientists have found some narwhals are delaying their journey, risking becoming trapped in sea ice with no openings to breathe through if the ice flash freezes in the fall.

Global warming can also cause destruction of habitats, such as coral reefs for sea creatures.

Light pollution is making migration more dangerous for some species as well, particularly birds. At the McCormick Place Lakeside Center, a Chicago building on the shore of Lake Michigan, more than 40,000 dead birds have been recovered since 1978, the report noted, having collided with it after being attracted to the light streaming from its windows.

Some mass whale strandings have been linked to sound pollution, while plastic pollution has been linked to mortality in albatrosses, large migratory seabirds.

The report sheds light on how creatures who make these often-spectacular journeys also play a vital role in upholding the Earth’s delicate ecological balance.

“These animals are, first and foremost, part of the ecosystems where they’re found,” CMS executive secretary Amy Fraenkel told CNN. “And we have a lot of evidence showing that if you remove these species, if they decline, it will have impacts on the ecosystems where they’re found, and not in a positive way.”

Take bats, for example. It can be hard to think of them as creatures that make the world a more beautiful place. But those that migrate have a crucial role as pollinators for a huge range of fruits and flowers — they pollinate more than 500 flowering plant species, the report says.

The bats disperse seeds, which help maintain healthy forests, and they regulate the spread of insects by consuming vast amounts of them.

But bats are threatened by deforestation, which destroys their habitat, as well as hunting — their meat is considered a delicacy in some countries. Noise pollution is also distracting for foraging bats, making them less efficient hunters.

There is some good news in the report. There are 14 species that have seen positive trends, including blue and humpbacked whales. But overall, the picture is alarming.

“Today’s report clearly shows us that unsustainable human activities are jeopardizing the future of migratory species – creatures who not only act as indicators of environmental change but play an integral role in maintaining the function and resilience of our planet’s complex ecosystems,” Inger Andersen, executive director of the United Nations Environment Programme, said in a statement.

The report was launched Monday at a major UN wildlife conservation conference in Samarkand, Uzbekistan.

Reducing the threats to migratory species will require global efforts, experts say, as so many animals who make these regular journeys cross international borders, whether on land, or in the sea or sky.

“Migratory species have a special role in nature as they don’t recognize political boundaries,” said Anurag Agrawal, professor of environmental studies at Cornell University. “Instead, they sew together large areas of the planet through their movements. Their conservation thus requires international cooperation.”

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