The range of the fastest land animal, the cheetah, has been reduced to just 9% of its historical range over Africa. With an estimated 1,500 of southern Africa’s approximately 4,000 free-ranging cheetahs, Namibia has the largest free-ranging population in the world. Around 95% of the population, however, occurs on commercial farmland.
With declining numbers, a question that comes to mind is: How healthy is Namibia’s population of free-ranging cheetahs?
The Department of Evolutionary Ecology at the Leibnitz Institute for Zoo and Wildlife Research (IZN) in Berlin, Germany, has been researching this question for nearly two decades. Its mission is: ‘Evolutionary wildlife research for conservation’. The Cheetah Research Project is headed by Dr Bettina Wachter, a senior scientist in the department.
Dr Wachter recently gave a presentation, ‘How healthy are free-ranging cheetahs in Namibia? Pathogen infections and immune responses of cheetahs’ at a Namibian Environmental & Wildlife Society (NEWS) meeting.
She said more than 33,000 samples have been taken from 300 free-ranging cheetahs, 100 captive animals and 50 dead cheetahs since the project started in 2000. Collars have been fitted to 230 free-ranging cheetahs to keep track of their movements. Tracking is done by air, enabling the team to inform farmers of the presence of cheetah and, thereby, decreasing potential stock losses.
Dr Wachter pointed out that cheetah are genetically monomorphic and, therefore, display relatively low genetic variability. This usually results in low reproductive performance, high cub mortality and a high susceptibility to diseases. Research on Namibia’s free-ranging cheetah population has, however, found that all females were reproductively active. Free-ranging cheetahs had a cub survival rate of 79% until their dispersal at 14 months. By comparison, the cub survival rate in Serengeti in northern Tanzania is a low 23% which Dr Wachter attributed to the presence of lion and other predators. The IZN research team also found that Namibia’s free-ranging cheetahs are all in good health with no clinical signs of infections or diseases.
A rather interesting, if not puzzling, finding was that although the cheetah falls within a grouping of species that exhibit low immunity diversity and should, therefore, be prone to diseases, they are not affected by diseases in any way.
Research has also been conducted on ectoparasites such as ticks and horse-flies and the prevalence of blood parasites. Although several parasites were detected in blood samples they did not cause diseases. The presence of gastrointestinal parasites was established by analysing eggs in the faeces of cheetahs. Research was also done on the blood serum of cheetahs, how their immune system responds to low genetic variability and the effect of age, sex, reproductive status and territoriality on the life history of cheetahs. A comparative study with another feline found that leopards are more immune to diseases than cheetahs.
Dr Wachter pointed out that the northern part of Namibia has a high cheetah population. Research has shown that cheetah from the central parts of the country have a low seroprevalence, while those of the north have a high seroprevalence. She said the more humid climate is one of the possible causes of the higher prevalence of pathogens in the northern population.
This has implications for the translocating cheetahs from central Namibia to northern Namibia or vice versa, Dr Wachter said. She suggested that if translocations are done vertically the cheetahs should be monitored closely as they might not have enough time to adapt to their new environment. Ideally, though, translocations should be done from west to east or vice versa.
In concluding her presentation, Dr Wachter said traditional conservation approaches are based on trial and error – which she compared to a black box. An alternative approach is to use a predictive framework. This includes research on behavioural ecology, genetic make-up, the immune system of the species, stress and reproduction. This approach, she said is like shedding light on the black box and although admitted that it is more time consuming and more expensive will produce more success when it comes to species conservation.
Dr Bettina Wachter, senior scientist in the Department of Evolutionary Ecology at the Leibnitz Institute for Zoo and Wildlife Research (IZN).