Cheetah Census

Cheetahs are shy and elusive and are notoriously difficult to census. These problems are further complicated in areas where land is privately owned, access is limited, the bush is dense and cheetahs are persecuted and are thus shy.

No standard method is available and accepted as reliable for censusing cheetahs. Several different methods have been used with various degrees of success. For these reasons it was decided to use several methods concurrently and to compare the results with the aim of finding the best possible method for censusing cheetahs.

It was decided to use three methods:

• The questionnaire method,
• Capture-recapture using remote camera trapping and
• Range use.

THE QUESTIONNAIRE METHOD

This method involves interviewing landowners and asking them questions from a standardised questionnaire. The questionnaire is divided into three sections. One relating to the details of the landowner: name, contact details, the next relating to information about the ranch: what type of animals occur there, what the main land use is, size of the ranch and type of fencing surrounding the property. The last section relates to information on cheetahs on the ranch: do cheetahs occur on the ranch, if so how frequently, sighting details, group sizes of cheetahs sighted, perception of cheetah numbers and attitudes towards the occurrence of cheetahs. This method is particularly useful for cheetahs as they occur in groups that are stable in size and composition. Males occur either alone or in coalitions that are stable for life. Females are either alone or with cubs which remain with their mothers for approximately two years. This makes groups of a specific size recognisable as it is highly unlikely that, for example, more than one coalition of three males will be present in a particular area.

This information is then analysed both spatially and statistically. Cheetah sightings are plotted on maps according to the date of sighting. This gives an indication of the movement of certain groups of cheetahs over several ranches. The relationship between different variables can then be tested, for example are cheetahs sighted more frequently on cattle or game ranches, or does the frequency of sighting of cheetahs affect the attitude of the landowner towards cheetahs.

This method is ideal on ranch lands where access is limited. It also allows for large tracts of land to be covered relatively quickly and cheaply. Some downfalls of the method are that it relies on human memory and honesty. It is also not very accurate and is not statistically sound.

Due to the nature of the interview method it allows for one on one contact between the field officer and the landowner. This means that reliable and accurate information can be transferred to the landowner both on cheetah biology and legal, non-lethal methods of controlling damage caused by cheetahs. This further allows for a mutually beneficial relationship to be established between the two parties.

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CAPTURE-RECAPTURE USING REMOTE TRIGGERED CAMERAS.

Capture-recapture studies are one of the oldest methods used for determining population size. The method is based upon capturing an animal, marking it and releasing it again. Then during a second trapping period, more animals are trapped. Then the ratio of marked vs. non-marked animals is used to calculate a capture probability, which is then able to be equated to give a population estimate.

With the development of remote triggered cameras, this method has become very useful for elusive animals. Remote triggered cameras work using an infrared beam which is linked to a camera. When the beam is broken, a photograph is taken. The spot patterns of every cheetah are unique, this means that individual cheetahs can be recognised from photographs.

This now allows for the adaptation of the capture-recapture method for cheetahs. Instead of physically capturing cheetahs, they are now photographed. When a cheetah is photographed, it is identified, given an individual number and considered ‘captured’. Whenever the same cheetah is photographed again, it is considered ‘recaptured’.

Data obtained in this manner are statistically sound and the experiment is exactly repeatable meaning that results can be compared over different seasons and years as well as different study areas. This method is particularly useful in ranching areas as most landowners will have no objection to having cameras placed on their properties, whereas not many will allow having cheetahs captured, collared and re-released onto their ranches.

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RANGE USE STUDIES

Understanding the range use patterns of cheetahs is vital in order to investigate their impact on game ranches and for investigating the density at which cheetahs occur. Range use is one of the basic biological measures that are needed to understand the habits and behaviour of a species in a specific area. Cheetahs are captured passively in box traps, immobilised and fitted with radio collars. These collars emit a frequency that is picked up by a receiver. This allows the cat to be located and its position recorded using a Global Positioning System. These fixes are then imported into a Geographical Information System on a PC, which then analyses the data and represents them spatially on a map.

When several different cheetahs are collared and monitored in a certain are, then the degree of range overlap can be determined. This then allows for estimates of cheetahs densities in the area.

A further advantage of the range use data is how it compliments other methods used for the census. As range use is better understood, the placing of camera traps becomes more accurate and the sightings of cheetahs recorded using questionnaires are more accurately understood.

Should you be aware of any cheetahs on your farm please fill in the quistionnaire on cheetah occurence.