Other scientists have found that little auks foraging in warm-water conditions have higher levels of the stress hormone corticosterone. In one study, by the end of the season, these adults weighed less and fewer of them survived the post-breeding months. So far, neither the adult birds nor their young in Wojczulanis-Jakubas’s study appear to have suffered. But she expects there will be a threshold—a point at which the birds aren’t able to compensate. “We’ll see it in body weight and, eventually, colony size,” she says.

Perched on the scree-covered slope, Wojczulanis-Jakubas points to the bright splashes of vegetation, draped along the base of the hills below us like blocky emerald necklaces. Wide pastures of chartreuse tundra extend to the coast. By Arctic standards, they are lush havens, buffets for Svalbard reindeer, Arctic foxes, Sibling voles, and barnacle geese. “It is an ornithocoprophilic tundra,” she says with a laugh. “A tundra that loves bird feces. It all starts with the little auks.”

The birds have engineered this terrestrial Arctic ecosystem, linking the sea to the land. Their poop is full of nitrogen, an essential nutrient for mosses, lichens, and dwarf willows, which in turn feed Svalbard’s mammals. Looking through binoculars to the other side of the fjord, the rocks are birdless, lifeless, and grey. “There is nothing,” Wojczulanis-Jakubas says. In the land stretching between the colony and the coast, as much as 100 percent of the nitrogen found in the vegetation comes from little auk poop.

It’s too early to say what will happen to the Hornsund colony or any of the other little auks on Spitsbergen. But there are hints that climate warming and a switch to the less-nutritious, boreal copepod could do them in. Little auks tend to return to the same breeding site each year, making relocation difficult should the birds’ foraging grounds deteriorate. And other researchers have already found links between warmer climate conditions in Spitsbergen and lower adult survival. They suspect the influx of boreal copepods may be to blame.

If the little auks disappear, or their numbers are reduced dramatically, it could change the landscape that plant-eating animals, such as reindeer, depend on. It’s possible that other seabirds might move in to fill the niche they leave behind. Still, the disappearance of a tiny copepod could remake the island’s unique biological fingerprint.

Overhead, a lone glaucous gull (Larus hyperborean) cuts lazy adagio loops through the sky, sending thousands of little auks into a discordant frenzy. They alight and fill the air with loud warning trills and the frantic whirring of wings.