The North Carolina Zoo has welcomed three litters of red wolf pups, bringing in a dozen new members of the world's most endangered wolf species.

The wolves were born during a three-day period in late April and are part of the zoo's red wolf breeding program, it said in a news release.

"All pups and their mothers are healthy and doing well. This is the first time in the Zoo's breeding program that three litters were born in one spring," the zoo said in the release.

Next month, the zoo plans to announce a public naming poll for one of the litters.

With the addition of the new pups, the zoo's breeding program now has 36 red wolves, making it the second-largest pack in the United States, after Point Defiance Zoo and Aquarium in Tacoma, Washington, the news release noted.

"These births are important because many of our wolves, once matured, have been moved to other breeding packs to continue to help bring this species back from near extinction. Our hope is that more and more red wolves can soon be placed into the wild," said Reid Wilson, the secretary of North Carolina's natural and cultural resources department.

The red wolf population began to decline in the United States due to intensive predator control programs and habitat deterioration, according to the US Fish and Wildlife Service, and were "decimated by the early 20th century." The service began conservation and recovery efforts in the late 1960s.

To date, the service estimates there are as many as 25 wolves in the wild, and 278 in captivity.

All of the wild wolves are in eastern North Carolina, the zoo said.