The African lion population has declined about 75 percent, with two-thirds of them disappearing in the last 50 years, reports a new study published Tuesday.

A team of international experts led by Duke University have estimated the current African lion population to be 32,000, down from 100,000 lions in 1960. Population growth and habitat destruction have been termed as the main reasons behind the huge loss in the population of lions.

"The word savannah conjures up visions of vast open plains teeming with wildlife. But the reality is that massive land-use change and deforestation, driven by rapid human population growth, has fragmented or degraded much of the original savannah. Only 25 percent remains of an ecosystem that once was a third larger than the continental United States," Stuart Pimm, Doris Duke Professor of Conservation Ecology at Duke's Nicholas School of the Environment, said in a statement.

Using high-resolution satellite imagery, human population density data and local lion population data, Pimm and his research team mapped the areas across Africa's savannahs that are suitable for the survival of lions. They found 67 spots that is favorable for lions to inhabit, with less human population.

Of the 67 spots, researchers identified 10 spots, most of them located within national parks, as strongholds for excellent chance of survival of the lions. There were no stronghold areas in West Africa, where the human population has doubled over the last 30 years. Around 500 lions remain in this region, spread across eight isolated areas.

Most of the areas were found to be unfit for the lions to live, as they were surrounded by human settlements. Moreover, deforestation and poaching have also contributed to the population decline.

The findings of the new study come just days after U.S. Fish and Wildlife Service  announced that it will study whether African lions have to be listed under the U.S. Endangered Species Act (ESA), following a petition filed last year by several conservation groups to list the African lions as protected species under ESA. The groups pointed out that trophy hunting and demand for lion products are the main factors contributing to their decline, reports The Washington Post.

Experts have urged to take better conservation efforts to protect the big cats. "A 75 percent reduction in extent of African savannah is stunning and grim. It emphasizes the urgency for conservation of these great habitats and their magnificent species like lions," said conservation scientist Thomas E. Lovejoy, from the George Mason University.

The findings of the study, "The size of savannah Africa: a lion's (Panthera leo) view", are published in the journal Biodiversity and Conservation.