Every summer, large colonies of Atlantic puffins gather on northern islands for the breeding season. These charismatic birds are a popular attraction for tourists and researchers alike. But in recent years, warming ocean waters have disrupted the birds' food supply, which can spell disaster for newly hatched chicks.
Machias Seal Island in the Gulf of Maine hosts a puffin colony of over 5,000 breeding pairs, larger than any other island in the Gulf. Over the summer months, puffin parents fly out to sea to collect food for their fledglings, who wait back on land in small burrows. In a typical year, about 60% of nests would see chicks grow up and leave at the end of the summer. But this year's numbers were much lower.
According to Tony Diamond, director of the Atlantic Laboratory for Avian Research at the University of New Brunswick, only 12% of this year's nests supported chicks to fledging, the lowest rate recorded in this colony in over 20 years. And the chicks weren't exactly healthy. "Those that fledged were often very small with lots of down left in their plumage, so I don’t expect … any of the chicks that hatched to survive long enough to breed," Diamond said.
The problem lies with the local fish populations. Puffins typically raise their young on diets of cold-water fish like white hake and sand lance, but warming waters have caused the sea life here to reorganise itself. According to scientists at the National Marine Fisheries Service, many creatures in the Gulf have been moving away from the coast looking for deeper, cooler waters, including the fish that puffins rely on to feed their chicks.
The birds on other islands in the Gulf are having similar problems. On Eastern Egg Rock and Matinicus Rock, puffins managed to replace their normal fish food with warm-water redfish, and had fairly normal chick survival rates. But it seems the puffins on Seal Island didn't have access to the redfish, and started hunting for less nutritious northern puffer instead, a species scientists have never seen them eat before. As a result, chick survival on Seal Island was low as well.
This problem goes beyond the Gulf of Maine. Across the sea in the Icelandic Islands, where puffins are traditionally hunted as a delicacy food, breeding colonies have been suffering food shortages for the past several years. In 2011, sea bird specialist Erpur Snaer Hansen told Ice News that breeding success that year was around 25% overall, with some colonies completely failing to bring up any young. Hansen suggested the combined pressures from warming waters and hunting by humans were just too much for the birds to handle.
As the puffins continue to struggle to find food, research suffers as well. Scientists in the Gulf of Maine normally put ID bands on the chicks before they leave their burrows, so they can be tracked through the years. "But we couldn’t this year because the chicks' legs were too small to hold a band," Diamond said. "We have never seen fledgling weights like this before."
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Top header image: Bjarni Thorbjornsson, Flickr
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