Lions living in the Zimbabwean reserve that was home to "Cecil the lion" are most threatened by human behaviour, including trophy hunting, researchers said Monday.

Cecil was shot by an American trophy hunter in 2015, sparking outrage after it emerged that the lion was not only a popular attraction for Hwange National Park visitors, but was also part of an Oxford University research project.

Human activity including trophy hunting accounted for the majority of lion deaths in Hwange, Oxford University said in statement released Monday.

In an analysis of the deaths of 206 lions living in the park between 1999 and 2012, human activities caused 88 percent of male and 67 percent of female mortalities, Oxford researchers found in a paper published in the Journal of Applied Ecology.

Male mortalities were mostly caused by trophy hunting, but the team found lionesses were killed in various ways, both when they wandered across park borders into agricultural or hunting grounds as well as at the hands of poachers within the park itself.

"Agricultural areas are intuitively identified by conservationists as being risky for carnivores due to retaliatory killings (by herders for livestock loss)," the researchers said.

'Important predator species'

The second paper, published in the Biological Conservation journal, showed that intensive trophy hunting of male lions in the early 2000s seriously affected the lion population.

A subsequent reduction in hunting quotas saw the lion population increase by 62 percent, with adult male numbers rising by 200 percent.

Researchers said this pointed to a need for "limited, well monitored and responsibly managed hunting quotas to be imposed where large predator populations are exploited".

"Conservationists face real and increasingly costly challenges in protecting these important predator species," Andrew Loveridge, lead author of both papers, said in a statement.

Loveridge said that solutions would need to include increased scrutiny and better management of trophy hunting as well as cooperation with farmers to limit the amount of livestock lost to lion attacks.

Anti-poaching measures would also have to be reinforced, he added.

Zimbabwe did not press charges against the US trophy hunter who paid $55,000 (52,000 euros) to shoot Cecil, dentist Walter Palmer, after it emerged he had legal papers allowing him to hunt.

The local guide who led the expedition, Theo Bronkhorst, was charged with "failing to prevent an illegal hunt", but the case against him was dropped last month.