Climate

Why Maine's Baby Puffins Are Growing So Slowly This Year

Many pufflings still have their immature downy feathers and have yet to fledge—signs of climate change tampering with seabird diets and survival.

Last summer the mid-coast of Maine saw its biggest Atlantic Puffin boom in decades. Colony numbers were up on all three of the area islands that Audubon manages: On Eastern Egg Rock, breeding pairs rose to 172 from 150 the previous year, and on Seal Island National Wildlife Refuge and Matinicus Rock, fledging success rates hit 80 and 86 percent, respectively.

So, when this breeding season came around, seabird scientists were hoping for another above-average year. What they've found, however, is that even with a good hatch (Eastern Egg Rock alone has 178 active nests), puffin parents are struggling to raise their chicks. Young birds on Seal Island and Matinicus Rock are taking nearly 50 percent longer to fledge due to a shortage of prey, likely stemming from a nearly two-degree increase in sea-surface temperatures around these remote islands.

The effects have been visible to the world through Grace, the star puffling of the Seal Island live burrow cam. She and her parents are still in their burrow weeks after their expected departure date because she hasn’t finished growing. At 56 days, Grace should have swapped nearly all of her gray natal down for a sleeker, mature black-and-white pelt. Instead, she’s maintaining her downy look, says Steve Kress, executive director of Audubon's Seabird Restoration Program. Things “are not going in the right direction right now,” he adds.

Normally, young puffins will fledge out of their burrows and follow their parents to the high seas by early August. This year, however, much of the colonies on Seal Island and Matinicus Rock have stuck around well into late summer to tend to still-growing offspring and their finicky diets. 

Puffin chicks typically dine on small, streamlined fish with a high fat content, such as herring or sand lance. But a decline in these prey has caused the birds to switch over to more-abundant haddock, a species that’s rebounded since an anti-overfishing law went into effect in the 1970s.

The swap was working well for the puffins—until this July, when haddock suddenly disappeared from the puffin chicks' diets. (When the surface temperature of the ocean rises, haddock and other fish swim to deeper, cooler, oxygen-rich waters, making it more difficult for seabirds to dive after them.) Right away, Kress and his team noticed a drop in the numbers of feedings at the puffin burrows, from up to 18 fish per day down to less than five.

An adult puffin on Eastern Egg Rock hunts butterfish and hake, two substitute fish species that aren't part of its ideal diet. Photo: Stephen Kress/Project Puffin

Facing famine, the puffin chicks tapped into one of their little-known adaptive powers: delayed onset of puberty. The young birds can live off fewer rations by stretching out their development to 60 days or more, rather than the normal 40 or 45 days. When they do so, they gain weight at a slower rate and retain their fuzzy down feathers for longer.

But according to Kress, in times like these, puffin parents have to make a tough decision: They can either feed the chick for the extra few weeks that it takes the chick to fledge, delaying their own migration and risking their personal wellbeing, or they can abandon the chick and try again the next breeding season, when, ideally, resources will be more plentiful. One thing’s for sure: If the adults leave while the chick is still developing, its chances of survival are slim.

Fledging late has its disadvantages compared to a typical schedule. These chicks often invest their limited resources in growing their wings at the expense of gaining body fat. Kress’s research has found that underweight fledglings are less likely to return to the colony to breed as adults.

In the comments section of the live-cam page, Kress posted a letter to educate viewers on the current phenomenon. The note touches on the impacts of overfishing, but mostly discusses the connection between global warming, marine prey, and baby puffins. “Climate change is hard for some to visualize,” he writes, "but watching individual animals like Grace and her family struggle to find food makes it easier to see.”

“We all care about the individual, but at the same time these birds are telling us that there's big changes going on in the ocean,” Kress continues. “Maybe it'll make some people that don’t believe in climate change understand that it is happening. That's the value of this.”

To those who find it distressing to watch the pufflings' slow development, Kress has a message: "Trust in puffins." They'll keep trying to beat the odds and do what they need to survive—all while sending warnings our way.

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