The Battle Over 2,500-Year-Old Shelters Made of Poop

NUUK, Greenland—Far up the coast of this ice-dominated island—north of the Arctic Circle; north of the glacier that spawned the Titanic-sinking iceberg; and north of the northernmost American military base—two birds of prey are locked in a vicious battle for food and territory.

Kurt Burnham has spent the past decade watching the fight take shape. He studies falcons at the High Arctic Institute, in Orion, Illinois, and he has traveled to Greenland most of the summers of his life.

For many of those trips, he helpedsurvey peregrine falcons that use western Greenlandas a summer nesting ground. But about a decade ago, he began tracking something new. As climate change tempered the Arctic’s frigid summers, peregrines were expanding their range north—farther north, he found, than there were ever records of them traveling before. Peregrine pairs began returning,