Atlantic Puffins are one of Iceland’s most recognizable summer visitors, making the country home to approximately 60% of the world’s population. These seabirds arrive annually to breed in massive colonies, yet for centuries, their whereabouts during the non-breeding season remained largely unknown, prompting their eight months at sea to be referred to as the “puffin mystery.” Thanks to modern tracking technology, scientists have now illuminated the vast, migratory journey that takes these small birds far across the North Atlantic Ocean.
The Annual Departure from Iceland
The end of the breeding season signals a shift from a crowded, social existence on coastal cliffs to a solitary life far from any landmass. From late August through September, the adult puffins depart their nesting burrows after their chick has fledged and gone to sea. This departure is driven by the diminishing food supply near the coast and the need to safely undergo their annual molt. At sea, the puffins replace their worn flight feathers, a process that temporarily leaves them flightless. The open ocean provides a safer, more secluded environment for this vulnerable period than the coast.
Mapping the Winter Migration Routes
Researchers employed geolocators, which record light levels to estimate location, to chart this migration. Data retrieved revealed that Icelandic puffins do not have a single winter destination, but rather disperse widely across the North Atlantic, often traveling over 1,000 kilometers from their breeding sites. The migration routes vary significantly, generally splitting into two major directions in search of productive foraging grounds.
One major migratory path takes some puffins westward toward the Labrador Sea, between Greenland and Newfoundland, and the waters off Eastern Canada. A second route leads other individuals southeast, with birds wintering in the Mid-Atlantic, including a known hotspot around the Charlie Gibbs Fracture Zone south of Iceland. This dispersal strategy suggests that the puffins prioritize finding high-quality feeding areas to build up energy reserves. Their winter distribution is a vast, ever-shifting area of the North Atlantic Ocean, rather than a single, concentrated wintering ground.
Surviving the Open Ocean
Once they reach their wintering areas, Atlantic Puffins adopt a pelagic existence, spending up to eight continuous months on the open sea without ever touching land. They are well adapted for this lifestyle, enduring the harsh conditions of the North Atlantic winter. Their dense, waterproof plumage and ability to drink salt water enable them to rest and sleep directly on the surface of the waves.
Puffins primarily feed by “flying” underwater, using their small, powerful wings for propulsion and diving to depths of 60 meters or more to pursue prey. Their winter diet consists of small, schooling fish like Glacier Lantern Fish and capelin. This diet is supplemented by invertebrates such as euphausiid crustaceans and squid, which they catch far from the continental shelf. During this time, they also shed the colorful plates from their beaks and their bright facial markings, a physical change that leaves them with a duller, gray appearance until the return of the breeding season.
Returning to the Breeding Colonies
The winter journey concludes in the early spring, with the first adult puffins beginning to reappear near the Icelandic coast in late April or early May. They congregate in large, floating groups just offshore, where they display courtship behaviors and prepare for their return to land. The vibrant colors of their beaks and the white facial plates are regenerated, signaling their transition back into breeding condition. They reunite with their mates, often returning to the exact same burrow they utilized in previous years.