A gangly, hooked-beak bird that makes sounds like a pig has recovered in massive numbers after the 1970s ban on the insecticide DDT, much like beloved bald eagles and ospreys.
But not everybody is glad about this success story.
Double crested cormorants flock to the Outer Banks this time of year by the thousands.
They are not very elegant. Cormorants are dark waterbirds about the size of a duck with long, crooked necks. Hooked beaks give them a prehistoric look. Bright orange patches stand out around blue-green eyes and the inside of their mouth is blue. During breeding season, two tufts of white feathers show over their eyes like an old man's eyebrows. Their call sounds like a pig grunting.
They spend the day either resting or fishing.
"They eat 250 species of fish," said Scott Anderson, bird conservation biologist for the North Carolina Wildlife Resources Commission. "They aren't picky at all."
Cormorants catch their prey by diving from a perch and swimming fast using webbed feet set further back than ducks. They can hold their breath for a long time.
"They swim better than they fly," Anderson said.
The birds gather around aquaculture ponds where they can devastate fish ready for market. Fish farmers can get a permit to shoot them or scare them away with pyrotechnics, but they come anyway.
Cormorants sit on the edges of the corral-like pound nets set in local rivers and sounds, picking off fish trapped within. The edge of the net hangs into the water from the weight of the predators, allowing fish to swim over top.
"It's a pain in the butt," said Willy Phillips, a pound net fisherman and owner of the Full Circle Crab Company in Columbia, North Carolina. "They sit on the net all fat and happy. It's like they're all hanging out at the club."
Cormorants love to feed on herring, a small fish that once made up a thriving fishery until the population collapsed. The state banned the herring commercial harvest in 2007. Cormorants aren't conducive to the recovery, Phillips said.
"I don't think the herring have a prayer given the water quality," Phillips said. "And it doesn't help to have those pterodactyls going down and wasting them."
Even their nesting habits are troublesome. Nests can be on the ground or in trees. Colonies can be large and over time, the guano destroys the trees. If they nest on the beach, their large numbers push out other nesting colonial waterbirds, Anderson said. Flocks are so dense they look like tar covering a distant sandbar.
They often stand with their wings spread out to dry since they do not have as much preening oil as waterfowl, according to the Cornell Lab of Ornithology. What appears as a disadvantage could be an adaptation. Wet feathers could help them swim faster under water, according to the lab.
The birds typically migrate south in the winter from breeding grounds around the Great Lakes, but more appear to be staying year round in some areas, Anderson said. Possibly 100 birds live permanently on the Outer Banks, he said. Florida has a large permanent population.
Cormorant numbers drastically declined in the middle of 20th century until the ban on DDT in 1972. Populations of fish-eating birds such as eagles, pelicans and ospreys began recovering. So did cormorants.
Some colonies doubled in five years in the Great Lakes areas, according to the Cornell lab. In places where they have overgrown the habitat, states have issued permits to oil the eggs, stopping incubation.
Cormorants still remain federally protected. Shooting does not appear to shrink the flocks anyway except in isolated areas or in breeding grounds, Anderson said.
They might even have some benefits such as eating predators of popular fish, but research on cormorants is limited. The state plans to conduct the first cormorant count in the area next year, Anderson said.