Johannesburg - Some call it the Cecil the lion effect.

A year ago, an American killed a lion in Zimbabwe in what authorities said was an illegal hunt, infuriating people worldwide and invigorating an international campaign against trophy hunting in Africa. Some conservationists, however, warn there are greater threats to Africa's beleaguered lion populations, including human encroachment on their habitats and the poaching of antelopes and other animals for food, a custom that deprives lions of prey.

The death of Cecil at Zimbabwe's Hwange National Park raised lions' profile on the "conservation radar", but most substantive steps in lion conservation since then have been directed against trophy hunting rather than bigger problems depleting lion numbers, said Luke Hunter, president of Panthera, a conservation group. Those measures include airline bans on the transport of parts of lions, rhino, elephants and other wild animals shot in hunts.

In a report marking the anniversary of Cecil's death in early July 2015, Panthera and two other conservation groups - WildAid and WildCRU - advocated more protection for lion habitats, measures to stimulate tourism and economic growth unrelated to hunting, and the supply of alternative sources of protein to local people to reduce demand for wild animal meat. Restrictions on hunting should be tightened as more data emerges on whether trophy hunting of some threatened species is even sustainable, the report said.

The number of lions in the wild in Africa has dropped by more than 40% to about 20 000 in the past two decades, according to estimates. Lion populations in West, Central and East Africa have dropped, though some conservation success has been recorded in the southern part of the continent.

Cecil, who wore a GPS collar and was being monitored by researchers, was killed in a protracted hunt in which he was, according to authorities, lured out of the wildlife park and initially wounded by an arrow. The death unleashed an extraordinary outpouring of anger at Walter Palmer, the American dentist who shot the lion, and other foreigners with means who have travelled to Africa to kill wildlife.