RIO DE JANEIRO, Brazil (AFP) — Chasing an endless summer, one shorebird species undertakes a grueling annual journey from the Arctic to the tip of South America and back -- a feat increasingly fraught with peril.

The Hudsonian godwit (Limosa haemastica) is one of the world’s most remarkable travelers, but its population has plunged 95 percent in four decades due to a complex mix of environmental changes across multiple countries.

It is one of 42 species proposed for international protection at a meeting of parties to the United Nations Convention on the Conservation of Migratory Species (CMS) in Brazil on 23 March. Together with the Hudsonian Whimbrel (Numenius hudsonicus), and Lesser Yellowlegs (Tringa flavipes), it was added to Appendix I of the CMS, the list of migratory species threatened with extinction, according to Manomet Conservation Science.

Migratory birds are facing “rapid and dramatic declines,” said Nathan Senner, an ecologist and ornithology professor at the University of Massachusetts Amherst who has studied the Hudsonian godwit for 20 years.

Scientists are still unraveling the mysteries of the shorebird — which can fly up to 11,000 kilometers in one stretch without stopping to eat, drink or sleep.

And it is only part of the 30,000 kilometers that the godwit travels every year from their breeding grounds in the Arctic to Patagonia where they spend the southern summer.

Disrupted migrations

In order to do this “epic flight,” they need “really predictable, abundant food resources” at every step of the journey, Senner told Agence France-Presse (AFP).

That predictability is crumbling.

In the Arctic, shifting spring timing attributed to climate change has created a mismatch between when chicks hatch and the peak availability of insects they feed on.

One of the puzzles Senner is currently working on is why Hudsonian godwits have begun migrating later by six days than they did a decade ago.

Something “has either disrupted the cues that they use to time their migrations or their ability to successfully and rapidly prepare for the migration,” he said.

In southern Chile, a boom in salmon and oyster farming has led to a build-up of infrastructure and the presence of people in the intertidal zones where they feed.

And in the United States, changes in farming practices are making the shallow water wetlands that the godwits rely on rarer and less predictable — meaning they spend more time looking for a place to stop and feed.

“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,” Senner said.

Essential to ecosystems

“Climate change is taking a heavy toll on species that rely on a ‘geological clock’ for their survival; many are disappearing,” Rodrigo Agostinho, president of Brazil’s environmental agency (Ibama), told AFP.

Among the species listed under CMS, a report released earlier this month showed that 49 percent now have populations that are declining, up from 44 percent two years ago.