By May, birds have returned north to breed and rear their young. They often nest on islands in the company of terns and gulls, great blue and black-crowned night herons, and great and snowy egrets. Nests are constructed from sticks and twigs and located in trees or on the ground. They usually contain from two to four light blue eggs. Both adult birds incubate the eggs for about 28 days by wrapping their feet around them, and care for their young until they become fully independent, about 10 weeks after hatching.
Cormorants are expert divers, adapted naturally to forage under water for fish.
Fully-webbed feet propel slim, streamlined bodies on dives usually from 8 to 20 feet. Greater depths are possible. Eye muscles are specialized to allow acute vision both above and under the water. Feathers absorb moisture, helping cormorants to stay under water for about 30 seconds. After foraging, cormorants often dry their feathers by perching in a distinctive wing-spreading posture.