Sunday , January 24 2021

Climate change may be making the Arctic more deadly for the young



Climate change may be launching good Arctic neighborhoods into killing fields for puppies.

Every year, coastal birds migrate thousands of miles from their winter refuges in the south to reach Arctic breeding sites. But what used to be a safer region for nesting birds now has higher predator risks than nesting in the tropics, says Vojtěch Kubelka, an evolutionary ecologist and ornithologist at Charles University in Prague. With many populations of wading birds decreasing, nest success is more important each year.

A long-time fan of seabirds, Kubelka had heard of regional tests of how the risk of predator changes from latitude to bird nests. He, however, wanted to be global. Seabirds make up a large group for such a comparison, he says, because there is not much variation in how nests look like predators. A ferocious dog in the United States and a fox in Russia are rising in some variation of a mild depression in the soil.

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Thus, Kubelka and his colleagues analyzed data from decades of predator attack rate records on some 38,000 nests of various tortoises, plovers and other seabirds. After a massive literature search, the study focused on the experiences of 237 populations of a total of 111 species of waders in 149 locations on six continents. It is the first attempt to globally compare the latitude of predator attack rates in wading bird nests over time, he says.

Historical data on predator attack rates around the world averaged 43 percent before 1999 but have since reached 57 percent, the team reports Nov. 9. Science. The most impressive rise came from reports of the Arctic nest. There, the rate of predator attacks has averaged 40 percent in the last century, jumping to 65 percent or 70 percent since 1999. Meanwhile, tropical hazards in the Northern Hemisphere have changed "only modestly," say researchers, from about 50 percent, to 55%. Percent.

The researchers also looked at how much and irregularly the temperatures changed in each location. Overall, the growing dangers to nests fit the trends of climate change.

Danger zone

In the last decades, the average number of nests attacked in 86 populations of arctic (rose) coastal birds has risen, surpassing even the average predatory danger in 17 breeding sites in the northern hemisphere (tan) and 96 populations in the northern temperate zone ( green).

Annual Shorebird Nest Attack, 19442016

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Biologists have discussed the idea that nest predation usually slows down when birds leave the tropics. One advantage of migrating to the pole to breed was, in theory, escaping the tropical abundance of snakes, rodents, and other egg lovers.

But rapid warming in the Arctic may have disconcerted some of the predator-prey relations, says co-author Tamás Székely, a conservation biologist at the University of Bath in England. For example, Arctic foxes used to derive much of their nutrition from lemmings, rats, and other small rodents. Snow cover weak in warmer winters, however, does not isolate small rodents as it used to. The cycles of growth and recession of lemming populations are, in many places, now "most of the time," he says. Foxes and other predators may be changing more for bird eggs and puppies.

This scenario of predators that love rodents and hunt more birds sounds "highly likely," but may be only part of what's happening, says Dominique Fauteux, an ecologist at the Canadian Museum of Nature in Ottawa who studies small mammals. Lemming collapses have not been reported across the Canadian Arctic, he says.

Instead, some researchers have proposed that flaws in the nest of shorebirds come from a geese boom that attracts more bird predators in general. In addition, a 2010 study suggests that predation of nests in the Canadian Arctic was still lower than in temperate areas. There may be some global pattern, but on the ground, Fauteux says, "there are clearly nuances."


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