We’re not the only species trying to fish around here.

28 06 2013

The U.S. Fish and Wildlife Service’sMaine Coastal Islands National Wildlife Refuge encompasses over 8,200 acres on more than 55 islands and coastal parcels. On eight of these islands, seabird restoration projects have been established to encourage and maintain nesting of Atlantic Puffins, Razorbills, and Common, Arctic and Roseate Terns. Working on a seabird island is, I can attest, challenging, and the summer researchers (many college students) stationed on the islands must put up with heat, harsh weather, primitive living conditions and not much contact with the outside world as the islands are closed to visitors from April through August. (They do apparently have enough access to modern conveniences to blog about the experience, so do check that out.)These researchers document numbers of pairs, numbers of chicks produced, what the parents feed those chicks, and how many survive to fledge.
The programs have been highly successful, with increases documented in nesting pairs of all five species over the 30 years the projects have been underway. Now, however, some troubling signs.

Arctic Tern on Petit Manan Island. (photo: USFWS)

Arctic Tern on Petit Manan Island. (photo: USFWS)

After 25 years of upward trends, numbers of breeding pairs of Arctic Terns in Maine have dropped by 42 percent, from 4,224 pairs in 2008 to 2,467 pairs in 2012. Linda Welch, Refuge biologist, reports that not only are the numbers of pairs declining, but among those pairs that do nest, fewer young are successfully fledged. Arctic Terns make the longest migrations of any birds in the world, traveling more than 36,000 miles round trip skipping out on the northern hemisphere’s winter to spend those months off Antarctica. They then fly north again to breed from New England up to the high Arctic. Scientists speculating about the decline in breeding success in these birds posit that they may be failing to find sufficient food while overwintering, and are returning to the breeding grounds with insufficient body reserves to reproduce (if they return at all).

Seabirds live a long time, and one lost breeding year would not be catastrophic, but this assumes that one bad year doesn’t turn into five, or ten. Additionally, the not-enough-food-in-the-Antarctic hypothesis does not necessarily explain why the birds that do breed seem to be less able to successfully raise their young. A likely reason: the same problem they may be facing over the winter. Not enough fish.

In 2007, 3,500 pairs of terns abandoned their nests on Machias Seal Island, up to that point the largest tern colony in the Gulf of Maine. The birds have never returned. Arctic Terns that do attempt to raise chicks seem unable to find enough of their accustomed food sources such as herring, and are, Welch says, “desperate. They try to bring in other kinds of fish or invertebrates for the chicks to eat. Sometimes the fish are too big for the chicks to swallow whole. So the chicks starve to death with all those fish carcasses lying around them. It’s really sad.”

Adult Atlantic Puffins on the breeding colony. (photo: USFWS)

Adult Atlantic Puffins on the breeding colony. (photo: USFWS)

The same saga is playing out among Atlantic Puffins, which also rely heavily on herring. Unable to find sufficient numbers of that prey, Puffin parents have been returning to the nest with butterfish, a warm water species gradually expanding its range northward while the herring, intolerant of warmer waters, are apparently moving deeper or farther north, out of reach of the beaks of terns and puffins in Maine. The broad, oval-bodied butterfish are mostly too wide for the young Puffins to swallow, and, like the terns, the birds gradually starve, surrounded by piles of food.

There is, of course, no way to link climate change to the death of a particular chick, or to a particular freak storm, or a single drought year. But we have overwhelming evidence of all these trends all pointing only one way, and as I watch this video of a puffin chick trying, for hours, to choke down a butterfish, I can think of no sterner indictment of what we have done than that fuzzy head and flat black eye gazing into a camera it doesn’t even know is there.

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