In the last two decades, African lions’ numbers have fallen by 30 percent, according to the International Union for Conservation of Nature. (PR Newswire)

Fearing that the world’s most iconic big cat could soon go extinct as humans invade its range, the Obama administration on Monday proposed listing the African lion as a threatened species.

The proposal by the U.S. Fish and Wildlife Service would make the African lion the last big cat to receive federal protection under the Endangered Species Act. In the last two decades, their numbers have fallen by 30 percent, according to the International Union for Conservation of ­Nature.

Over that time, human development into areas inhabited by lions has increased. Their prey “is hunted by humans at unsustainable levels” for bush meat, the federal agency said in a statement. To survive, lions kill livestock, and in response, ranchers slaughter lions.

“Demographers believe the human population in sub-Saharan Africa will double by 2050,” said Daniel M. Ashe, the director of Fish and Wildlife. “Unless things improve, lions will face extinction. It’s up to us and not just the people of Africa to ensure that lions will continue to roam.”

The agency will seek public comment for 90 days. Several groups, including the International Fund for Animal Welfare, the Humane Society of the United States and Defenders of Wildlife, petitioned the government in 2012 to list the African lion as endangered, a category that offers slightly more protection than the threatened designation. Tigers, leopards, cheetahs, jaguars and pumas are all listed as endangered.

There were about 75,000 African lions in 1980, according to the best estimates, said the IUCN. Now there are between 32,000 and 33,000, most concentrated in 10 areas in eastern and southern Africa.

After a two-year analysis, Fish and Wildlife stopped short of designating lions as endangered, saying they are not at immediate risk of extinction. Ashe said the agency proposed the threatened designation because lions are likely to “disappear in the foreseeable future” if they are not protected.

Hunting an animal listed as endangered in Africa is legal if the host nation permits it, but the remains of the animal cannot be imported to the United States for a trophy. Hunting and trophies are allowed in the U.S. for threatened animals, but hunters must apply for permits and the government can refuse a permit if it believes the plight of the species has worsened.

Ashe said hunters are not responsible for the decrease of lions in Angola, Botswana, South Africa, Kenya, Zimbabwe, Senegal, Mozambique, Uganda and about 20 other nations.

Under the threatened designation, Fish and Wildlife will put in place a new permitting system for importing lion hunting trophies into the United States, Ashe said. Such trophies will be permitted only from nations that carefully use hunting as a way to manage lions to help preserve the species. The proposal takes about a year to become final.

Fish and Wildlife will want to know “what’s happening to the revenue that comes” from hunting, Ashe said. “Does it go back to support the conservation of the species in the wild? What do they have to show us to determine if there’s a clear conservation benefit?”

The government’s action was praised by both supporters and opponents of the petition from the environmental groups. Safari Club International applauded the proposal as a win for hunters and a loss for conservation groups that sought the endangered designation that would have prohibited the importation of trophies, a big lure for hunters.

1 of 15 Full Screen Autoplay Close Skip Ad × Wildlife Photographer of the Year contest View Photos Now in its 50th year, the contest, by the Natural History Museum and BBC, has announced its top images. Caption Now in its 50th year, the Wildlife Photographer of the Year contest, by the Natural History Museum and BBC, has announced its top images. Winner, Black and White Overall During the rains, this unnamed kopje (rock outcropping) has a water hole that brings prey for the Vumbi pride. On this afternoon, the lions rested closely together after all five females attacked Hildur, the second male in the resident coalition. Why? Maybe simply because there was not enough food to share. Michael Nichols/Wildlife Photographer of the Year 2014 Buy Photo Wait 1 second to continue.

“This conclusion is a blow to the anti-hunting rhetoric put forward by organizations such as the Humane Society of the United States and International Fund for Animal Welfare,” the group said.

“By rejecting an endangered listing, the FWS has officially recognized the reality that the African lions are not actually on the brink of extinction,” said the club’s president, Joe Hosmer.

But one of the authors of the petition, Jeff Flocken, North America regional director of IFAW, also hailed the proposal as a victory.

“We’re excited. African lions are the only big cat not receiving protection until now because they’re a coveted trophy,” Flocken said. “It is a win for lions.”

Jane Goodall, founder of the Jane Goodall Institute, congratulated Fish and Wildlife, calling the designation “excellent news.” African lions have been “decreasing in numbers steadily,” yet ­people were not aware of the decline because they see the animals in parks and reserves, she said.

“I hope that the proposed listing will be approved,” Goodall said. “How terrible to lose the ‘king of beasts’ from the African scene.”