Can you think of any Alaskan communities that have populations of a million or more? Welcome to Field Notes, I’m Dianna Swaim, a volunteer biological technician with the Togiak National Wildlife Refuge.

Each summer more than 50 million seabirds fly to Alaska from around the Pacific to breed and raise their young. Most of these seabirds are pelagic. They live offshore on the ocean for 8 to 9 months of the year, with no need to set their webbed feet on dry land. During spring, however, these seabirds begin to congregate along the coast in “bird cities” or colonies, some of which can reach populations 4 to 5 times the size of Anchorage.

Seabirds usually choose remote and isolated places such as rocky cliffs, coastal bluffs, and islands free of land predators to establish their colonies. These birds feel safe in large numbers and choose places where hundreds, thousands, and sometimes millions of individuals can pack together and nest. Nesting behavior is encouraged in areas where there is a great amount of activity going on like squawking, flying, mating, feeding, and gathering of materials.

Seabirds are able to live in such large colonies because each species occupies a different nest site. These nest sites range from boulders to the tops of cliffs. Pigeon guillemots prefer boulder rubble, least auklets prefer talus, black-legged kittiwakes prefer cliffs, horned puffins like rock crevices, common murres prefer cliff ledges, rhinoceros auklets like burrows, while glaucous-winged gulls prefer flatter ground. Each of these bird species obtains most of their food from the ocean, but the various species have different adaptations that allow them to dive to different depths, thereby utilizing different marine resources.

Alaska is one of the richest marine bird areas in the world. Over 85% of the total U.S. seabird population can be found in the state. To monitor the health of our oceans, seabird populations are often studied. Environmental changes in the ocean can be detected by studying the health and productivity of seabirds. For Field Notes, I’m Dianna Swaim.