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Climate change is causing this bird to shrink: Study

An overheating planet isn't pleasant for several species, but for one migratory bird, climate change is causing it to shrink in size and put its survival at risk, new research suggests.

With global warming having a dramatic impact on the High Arctic, the environmental change to the Red Knot's (Calidris canutus) nesting ground is putting its access to sufficient nutrients in jeopardy.

Red Knots
Photographer Credit: © Jan van de Kam, NL
Red Knots

Using 33 years' worth of satellite images and data, an international team of experts observed how Arctic Russia's snowmelt was happening progressively earlier on in the season—at a rate of half a day annually—as years went by.

Consequently, as the snow thaws earlier, red knots are finding it more difficult to hatch in time for the annual peak of insect food, which is sparked by the snowmelt. The lack of food causes red knot chicks to develop a smaller build and tinier bill, ahead of the bird's migratory journey to the tropics.

The shorebird typically spends its first two months of the year (June/July) in the Russian Arctic, before it flies to the tropics, where it spends most of its time annually. But the Arctic isn't the bird species' only problem.

Published in academic journal "Science", researchers submitted a second problem when the birds reach their new wintering grounds in West Africa or other tropics: the case of a smaller bill.

Depending on their body size, a red open is likely to have a much stronger chance of living if it has a longer bill, due to what food it can attain. Birds with bigger bills can reach shellfish or bivalves, a type of mollusk that can be buried deep into the mud.

Red Knots
Photographer Credit: © Jan van de Kam, NL
Red Knots

If birds cannot obtain these foods, they will have to settle for seagrass, which is less nutritious compared to shellfish, the report's first author, Dr. Jan van Gils from Royal Netherlands Institute for Sea Research, explained to CNBC over the phone.

While some studies see animals decreasing in size so they could adapt to a hotter environment, the team's research in West Africa highlighted how being smaller was a disadvantage to the red knots.

In 1980, there were around half a million of these red knots, however today, this has halved to some 250,000, van Gils told CNBC over the phone.

"That makes me very pessimistic that climate change is something that will not stop and the population size is going down rapidly. So I foresee big problems in the future for this species and probably not only for this species," van Gils said, adding that this is likely to happen to other species in the High Arctic.

Van Gils did however, add that there was a small "fraction" of red knots who could be born with a smaller body and larger bill, however the majority were at greater risk. To have the highest chance of survival and living until adulthood, a long bill was essential.

Van Gils suggested that along with countries tackling climate change, more protection was needed when birds stopped off in the tropics, such as making sure birds receive the right amount of shellfish, which could otherwise be impacted by fisheries.

"This is a very serious ecological effect that requires our immediate attention," van Gils said in a statement accompanying the report.

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