"As much as I really dig big cats - they are magnificent creatures that are endlessly fascinating and wonderful to spend time with - there is also this overwhelming need to do the conservation," says Hunter, who is now the executive director of the Panthera Foundation, a conservation group in New York.

There are 36 species of big cats around the world and all have suffered a large decline in number over recent decades. "In general, the larger the animal, the more endangered they are," Hunter says. "Larger carnivores need bigger areas with lots of prey in them, which are increasingly under threat for various reasons."

One of the main reasons is the gradual encroachment of humans onto the carnivores' land. This also brings farmers and others into conflict with the animals - a battle in which the lion or tiger almost inevitably comes off second best. Add in the continuing appetites of hunters and poachers and, says Hunter, there has never been more need for the work of organisations such as Panthera.

"Tigers are the most imperilled large cat," he says. "They are definitely close to a crisis and are down to about 5000 individuals in the wild. More dramatically, they now exist in just 7 per cent of their historic range."

Another species that takes up a lot of Hunter's time is the African lion. It is, he says, easy to believe that all is relatively well with lions in Africa, especially if you visit one of the vast reserves there where the animals are very visible. But outside the key protected areas, lions are "getting hammered".

"Apart from all the normal threats like loss of habitat, it's mostly about livestock. Lions live in big groups and they are a big, dangerous animal, and people just don't want them around."

One innovative approach being used successfully in some parts of Africa is to help the farmers take better care of their cattle by, for instance, always being with the herd in the bush, using dogs as a lion "early-warning system" and protecting them in thorn tree corrals at night.

"This is not a new idea," Hunter says. "The model, in fact, comes from the Masai [an ethnic group from Kenya and northern Tanzania], who traditionally have done a fantastic job of taking care of their cattle."

Another way to stop farmers killing lions is to reduce their stock losses from other causes, such as disease, to the point where the occasional cow being taken by a marauding lion becomes less of a problem.

"We can do it really simply with vaccinations," Hunter says. "We go in to deliver that service and then part of our agreement with the community is that if we address the disease issue to increase their productivity and reduce their losses, they will in turn agree to stop killing carnivores."