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Why migrating birds go the distance
White-rumpled Sandpiper (Calidris fuscicollis) chicks, Bylot Island, Nunavut.
[Image courtesy of Laura McKinnon]
Arctic Shorebirds travel grueling distances each year as they migrate to their breeding grounds in the harsh, remote Arctic, but they do get a payoff, scientists report in a new study. The birds' eggs are less like to be eaten by foxes and other predators.
Arctic-nesting birds have quite impressive migratory strategies, such as flying from wintering areas at the southern tip of South America, southern Africa and Oceania to their breeding grounds in the Arctic. Scientists know a lot about the physical toll these journeys take on the birds' bodies and how the birds actually manage to make the trip. But, why the birds travel so far has been a mystery.
Laura McKinnon of the University of Quebec and colleagues wondered whether a key reason might be that the birds' eggs were less likely to be eaten by hungry predators in the far north. To test their hypothesis, they filled over 1,500 artificial nests with eggs and placed the nests at seven shorebird breeding sites along a stretch of the Arctic, spanning more than 3,000 kilometers, north- to-south.
The researchers monitored the nests for at least two summers, and found that the nests farther north were, in fact, less likely to be preyed upon. These findings appear in the 15 January issue of the journal Science.