"That bony potbellied arrow, wing-pumping along implacably, with a ramrod's rigid adherence, airborne, to the horizontal, discloses talents one would never have guessed at."
from The Cormorant in Its Element by Amy Clampitt.
Double-crested cormorants have seen hard times. In the 1960s they were threatened across the United States by the use of the pesticide DDT, along with Peregrine Falcons and Bald Eagles. Thanks to a federal ban on DDT and the passage of the Clean Water Act, cormorants have recovered. They showed up in New York Harbor in 1985. Now I see them often in the East River. There are usually a few loafing on the pilings at the southern end of the waterfront promenade on Pier One in Brooklyn Bridge Park.
Double-crested cormorants are large, slender, short-tailed, birds about 30 inches long. Their necks are kinked. Their eyes are blue. Their bills have a hook at the tip. They have an area of bare bright orange skin on the face and throat. Adults are black with a greenish sheen. Immature birds are gray on the neck and breast.
They dive underwater to chase fish, swimming after them and grabbing them with their bills without spearing. Some of the cormorant's feathers are specially structured to decrease buoyancy so they can dive efficiently. The special feathers get wet during dives; cormorants typically sit in the sun with wings spread to dry them after diving. Just the outer feathers get wet, so the cormorant is still well insulated by a layer of air next to its skin and able to dive in cold water.
Cormorants swim low in the water and sometimes all we see of one is its head and neck. They dive from the surface, propelling themselves with their feet. They can dive to about 25 feet and stay under for more than a minute. They eat smaller fish while underwater, but sometimes bring big ones to the surface. You may see them slap a fish on the water surface, and then toss it in the air to swallow head first.