Climate change could make Arctic more deadly for chicks

Climate change may turn good arctic neighborhoods into killing grounds for chicks.

Each year, shorebirds migrate thousands of kilometers from their winter shelters in the south of the country to reach the Arctic breeding grounds. But Vojtěch Kubelka, an evolutionary ecologist and ornithologist at Charles University in Prague, believes that predators predicted more than nesting tropical birds. With the decline of many shorebird populations, nest success counts more every year.

Longtime keen on shorebirds, Kubelka has heard of regional trials on how the predator risk changes depending on the latitude of the bird nests. However, he wanted to become global. Shorebirds are an excellent group for such a large-scale comparison, he says, because there is not much variation in how nests look like predators. A wild dog in the United States and a fox in Russia both feed on a slight depression in the soil.

Kubelka and his colleagues have collected data from decades of records of predator attack rates on about 38,000 nests of sandpipers, plovers and other shorebirds. After a massive literature search, the study focused on the experiments of 237 populations of a total of 111 species of shorebirds at 149 locations on six continents. This is the first attempt at a global comparison by the latitude of predator attack rates on shorebird nests over time, he says.

Historical data on predator attack rates around the world averaged about 43% before 1999, but have since reached 57%, the team announced on November 9th. Science. The most dramatic increase came from reports on arctic nests. The rate of predator attacks has averaged 40% in the last century, rising to around 65 or 70% since 1999. At the same time, tropical perils in the northern hemisphere have changed that "modestly," according to the researchers, rising from about 50% to about 55%. percent.

The researchers also examined how and at what rate temperatures had changed at each site. Overall, the increasing dangers for nests correspond to the trends of climate change.

Biologists have discussed the idea that nest predation usually declines as birds leave the tropics. One of the advantages of migration to the pole to breed was, in theory, to escape the tropical abundance of snakes, rodents and other lovers of eggs .

But the rapid warming that reigns in the Arctic could have hurt some of the old predator-prey relationships, says co-author Tamás Székely, a conservation biologist at the University of Bath in England. For example, arctic foxes fed mainly on lemmings, voles and other small rodents. A narrow snow cover during warmer winters does not isolate small rodents as much as before. The cycles of expansion and collapse of lemmel populations are in many places now "essentially collapsed," he says. Foxes and other predators may move more towards eggs and chicks.

According to Dominique Fauteux, an ecologist at the Canadian Museum of Nature in Ottawa, who studies small mammals, the scenario of rodent-hungry predators looking for more birds seems "very likely". Lemming collapses have not been reported throughout the Canadian Arctic, he says.

Some researchers have instead proposed that shorebird nest failures result from a boom in geese that attract more bird predators globally. In addition, a 2010 study indicated that nest predation in the Canadian Arctic was even lower than in temperate zones. There may be a global trend, but on the ground, says Fauteux, "there are clearly nuances".