Dale Gerhard, Associated Press
In this May 23, 2005, photograph, a red knot, center, feeds among ruddy turnstones and sanderlings along the Delaware Bay shoreline in Middle Township, N.J. On Tuesday, Dec. 9, 2014, the federal government has ruled that the rust-colored shorebird known for its long migration is a threatened species.

TRENTON, N.J. — The federal government has ruled that a rust-colored shorebird known for its 10,000-mile migration is a threatened species.

After a 14-month review, the U.S. Fish and Wildlife Service on Tuesday listed the rufa subspecies of the red knot as threatened. Under the Endangered Species Act, the ruling prohibits people without a permit from killing, shooting hunting or otherwise harming the bird.

The threatened status means a plant or animal is likely to become endangered in the foreseeable future. Endangered means the species faces extinction.

New Jersey already protects the bird, ruling the red knot endangered in 2012.

The bird has pencil-thin legs and a slender beak and migrates nearly 10,000 miles from South America to the Arctic every spring, reversing the trip in the fall. The birds can fly nearly 1,500 miles without rest.

One of those stops is along the Delaware Bay in southern New Jersey, where the birds' numbers have fallen from 100,000 to about 25,000.

The birds feed on small bivalves — clams and mussels. They also eat horseshoe crab eggs found in the Delaware Bay. The eggs are rich in nutrients that allow the bird to double their bodyweight and trek north to the Arctic.

"Imagine if you are driving across the country and there are only two or three pit stops to fuel up and get food and if you don't, it's all or nothing. Either you make it or you don't," said Eric Stiles, president of New Jersey Audubon.

The Fish and Wildlife Service links the bird's decline to climate change and rising sea levels, which affect the bird's habitat and the availability of food.

"Although historic threats in the Delaware Bay area have been ameliorated thanks to the actions of federal and state partners, our changing climate is posing new and complex challenges to the red knot's habitat and food supply," Fish and Wildlife Service Director Dan Ashe said in a statement.

Because New Jersey has already listed the bird as endangered, conservation efforts likely won't change drastically in the state, Stiles said. The bay is already a protected habitat, law enforcement helps protect the bird from harassment and funding for research is in place, he said.

The main advantage of the federal listing is cross-state coordination, Stiles said.

The red knot was one of many species harmed by Superstorm Sandy, although officials said last year that the storm would play little or no role in the decision to list the bird as threatened.

The bird is an incredible voyager. Beginning its journey at the southern tip of South America, the red knot stops in Brazil and in coastal New Jersey on its way to the Arctic.

One bird earned the nickname Moonbird because researchers calculated it had flown enough miles to reach the moon and about half the way back, according to the Fish and Wildlife Service.