Seabirds, Pacific Northwest
Double crested cormorants are dramatic, large aquatic birds. They don’t have waterproof feathers like most aquatic birds and need to perch, with wings spread out, on rocks, pilings or docks to dry off.
Double crested cormorants occupy many water habitats across North America, including coastlines, estuaries, lakes and ponds. Most spend winter in the southern United States but many migrating birds winter on the south coast of the Pacific Northwest.
The south coast has various breeding colonies and a large year round population. During the breeding season, cormorants are monogamous and live in large, social colonies. Cormorant couples work together raise their young, from building a nest and incubating the eggs to feeding chicks once they have hatched. Unpaired males will search for females shortly after choosing a nest site. Once a mate has been found, the male will bring nest material to her, and the female does the building. The nest is a platform of sticks and debris, usually found on a rocky cliff above water, but could be the ground, or even in a tree. Over a few weeks, the nest materials become cemented together by droppings.
The female will lay up to 4 eggs and both parents take turns incubating them. After hatching, the young are fed regurgitated food by both parents. After leaving the nest, the young roam the colony in groups called creches and return to the nest site only when they are hungry. The young are completely independent of their parents at 10 weeks.
Cormorants will sometimes rebuild an old nest rather than start a new one from scratch. And when they find pieces of useful junk, like old bits of rope, net, or other beach debris, they will often incorporate this into their nests. Sometimes these nests can look pretty wild.