2,500 nests in Alaska show that nesting is taking place up to seven days earlier, reports
Tim Radford for Climate News Network, part of the Guardian Environment Network
theguardian.com, Tuesday 8 July 2014 15.13 BST
Arctic migrants are nesting up to seven days earlier as the world warms. The sandpiper makes a beeline for the Alaskan shores, to join the phalarope on the beach and the songbirds in the woods − and all because the winter snows are melting earlier.
Conservation scientists Joe Liebezeit and Steve Zack – both then of the Wildlife Conservation Society (WCS) – and colleagues report in the journal Polar Biology that they looked into nearly 2,500 nests of four shorebird species in Alaska – two sandpipers, two phalaropes − and a songbird called the Lapland songspur over a nine-year period.
They recorded when the first eggs were laid. And they also assessed snow melt in nesting plots at different times in the early spring, and took note of predator abundance and the seasonal flush of vegetation − both of which can affect nest timing − to see what mattered most in terms of breeding.
“It seems clear that the timing of the snow melt in Arctic Alaska is the most important mechanism driving the earlier and earlier breeding dates we observed in the Arctic,” said Liebezeit, now of the Audubon Society of Portland, Oregon.
“The rates of advancement in earlier breeding are higher in Arctic birds than in other temperate bird species, and this accords with the fact that the Arctic climate is changing at twice the rate.”
During the nine years in which the scientists conducted their study, they found that nesting advanced by between four and seven days.