By Dr Laurie Marker and Bonnie Schumann, Cheetah Conservation Fund
Depending on who you ask, the answer will vary from ‘too many’ – which in most cases will come from the farming community – to a more cautionary response of ‘around 3 000’ or ‘we simply don’t know’ from members of the conservation community.
Namibia has been dubbed the Cheetah Capital of the World, yet we still have only an estimate of our cheetah population, despite years of research by the Cheetah Conservation Fund (CCF) and others aimed at answering this tricky question. The CCF’s goal to develop census methods in the wild as an index of cheetah population density and distribution is critical to setting conservation priorities and has far-reaching benefits for cheetah in Namibia and in other range countries.
Difficult to census
Why is it so hard to count cheetah? Because cheetah have not read the book on Censusing Carnivore Populations and do not conform to behaviour patterns conducive to counting them! For a start they have extremely large home ranges, averaging 1 600 square kilometres, the largest found in any range country, or for any of the big cats. Secondly, they are solitary by nature, although the males are often found in coalitions. No easy counting of packs or prides and extrapolating! Thirdly, they are extremely elusive. Added to the bush-encroached habitat they live in, this eliminates using conventional visual counts. Fourthly, as is the case in most range countries, our cheetah population is found primarily outside protected areas, compounding the logistics of working in their habitat, as privately owned land cannot be traversed as freely by researchers as it can by their subjects, which have no regard for fences or locked gates.
Undaunted by the challenges, CCF researchers have tried and tested various methods for suitability as the technique to monitor our cheetah treasure over the long term. Beginning in 1993 with a long-term radio-telemetry project, for the next 10 years an average of 15 groups of cheetah were tracked around the Otjiwarongo area, enabling us to learn more about the spatial ecology of these secretive felines. With average home ranges covering eight to 10 commercial farms, a minimum density was established of 2.5 cheetah per 1 000 km2.
In 1998 a ‘tag and release’ project was launched countrywide, in the hope of tapping into the numbers of cheetah caught by farmers each year. This failed, due to the low numbers trapped during the designated study period. Thus snaring was looked at, not of the cats, but of some of their spotty coats, as the hair holds valuable DNA in its roots that could help identify each individual snared within a study area. CCF staff placed scent lures in areas cheetah were known to frequent, the plan being that they would rub against the lure and part with some of their hair. Once again, although this technique has been used successfully worldwide on a variety of felids, cheetahs showed a total disregard for what they were expected to do and happily ignored the lures. So, back to the drawing board, and building on its long-term research, CCF began field-testing and calibrating other indirect methods for cheetah censusing.
By now CCF researchers were more than a bit desperate. They decided that trapping and shooting was the only option. Fortunately in this case the weapons of choice were a vehicle and remote censusing cameras.
Since 1994, the CCF has carried out monthly spoor-frequency studies in the Waterberg Conservancy area. This entails driving though a designated route and identifying spoor (tracks). These tracks, once analysed, contribute to what we know about the cheetah population in this area. This area hosts mixed wildlife and livestock (cattle, goats and sheep) farms and is typical ‘cheetah country’. Spoor frequency, as a measure of actual density, has been used successfully for measuring populations of several low-density large carnivores in Namibia. However, it has been used mostly in conservation areas and its applicability to estimate free-ranging wild populations was poorly understood.
Undaunted, CCF master’s-degree student, Ezekiel Fabiano, drove over 3 483 kilometres (over 580 kilometres per year) on a designated track, finding an overall cheetah spoor frequency of 151.4 kilometres per cheetah spoor and an overall converted annual spoor density for the five-year study period of 7.2 cheetah per 1 000 square kilometres. You need to drive a minimum sampling distance of 1 655 kilometres for spoor tracking to minimise variability in spoor frequency. After covering thousands of kilometres, the CCF is getting closer to its goal of knowing how many cheetahs there are.
Counting by camera
Don’t all cheetahs look alike? Although at first glance impossibly spotty, each cheetah’s coat pattern holds the key to its identity, rather like a human fingerprint. The left and right body-spot pattern and barring on the tail are unique to each individual. Capture that cheetah on film, or even better, capture enough of the individuals in a given area over a specified window of time on film and you effectively have a head count of who’s who in your study area. The camera trap-census method provides the necessary data to estimate the abundance and density of animals in the surveyed area without necessarily ‘trapping’ all the individuals in a population.
In 2006, the CCF completed its first three-month cheetah population survey on a 600-square-kilometre study area within the Waterberg Conservancy (300 square kilometres, the actual area covered by the cameras, being an effective area). Using two remotely triggered cameras at 14 stations from November 2005 to February 2006, over 350 rolls of film were taken, resulting in 6 826 exposures. Of these exposures, 467 (7%) were cheetah pictures that have been incorporated into an extensive digital database by CCF researchers Matti Nghikembua and Ezekiel Fabiano. The photos were shot over a period of 1 209 trap nights, at a rate of one cheetah per three trap nights. Preliminary results indicate a density of 12 cheetahs per 1 000 square kilometres (SD +12.9) in the Waterberg Conservancy area.
So, with the help of modern technology in the form of the humble camera, the secrets of the number and trend of the Namibian cheetah population are finally being revealed. And, to assess the validity, the camera trap results will be calibrated with the minimum known densities with other indirect census techniques to find the best way to ‘count’ cheetahs.
Although these current methods are very promising, even more innovative methods await us in the future. DNA can also be extracted from scat (feaces). The CCF calls this Black Gold! At present, DNA-based methods for identifying individual cheetahs using scat samples are in the process of being developed; individual cheetahs have already been identified by CCF researchers using DNA derived from blood samples with micro-satellites. Developing techniques to extract and analyse DNA from faeces has enormous potential for conducting accurate field census methods for cheetah. Work is underway in East Africa to investigate the use of man’s best friend, in the form of ‘sniffer’ dogs to locate scat samples in the field. This method will soon be trialled by CCF in Namibia.
By using a combination of these techniques, a reliable index of cheetah numbers can be established, allowing for an accurate assessment of cheetah populations on Namibian farmlands over time. This information is vital to help develop the most appropriate conservation strategies and management policies for cheetah in Namibia and throughout their ranges in Africa and Iran.
This article appeared in the 2007/8 edition of Conservation and the Environment in Namibia.