Martin Meissner / AP

Trophy lions include this stuffed specimen at an international hunting exposition in Dortmund, Germany, in 2011.

If wildlife activists have their way, U.S. hunters trekking to Africa soon won't be able to bring back any lion skins or skulls as trophies.

Acting on a petition by those activists, the U.S. Fish and Wildlife Service on Tuesday said it will study whether the species warrants protection under the Endangered Species Act.

Born Free USA, one of the petition groups, called the review "the necessary first step toward ensuring a chance at survival for this beleaguered species."

African lion populations have seen "a substantial decline" over the past two decades and are estimated to be around 32,000, according to the International Union for Conservation of Nature, which monitors species numbers globally. 

The threats include not only trophy hunters, but loss of habitat, humans eating lion meat, and commercial sale of their body parts, said Adam Roberts, executive vice president of Born Free USA. 

As humans move into lion habitat, he added, that increases "retaliatory killings, including by gruesome poisoning," of lions that go after livestock.

The Fish and Wildlife Service began a 60-day period to receive public and expert comment on whether to list the species. The Asian lion was listed as endangered in 1970.

In their petition, the activists cited U.S. trade figures showing that more than 5,600 wild Africa lions were hunted and then exported as trophies between 1999 and 2008, with 64 percent of those trophies being imported into the U.S.

Trophy hunters counter that while their hobby is regulated, licensed and recorded, the slaughter of lions by locals protecting livestock is rampant and largely uncontrolled. 

Many African nations with lion populations they consider healthy allow trophy hunting as a way to bring in revenue for locals as well as to help fund wildlife programs.

The U.S. has listed non-native animals before since the act is meant to ensure the U.S. citizens "do not contribute to the further decline of that species in its native habitat," the Fish and Wildlife Service said in its announcement.

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