This article, which has been divided into three sections, was written by Dr. Salomon Joubert in 2010.
What had been conveyed to me was that a statement had been made to the effect that elephants could not be censused from the air. This was due to the fact that not all the animals could be spotted. A slide was apparently screened on which only some 5 individuals out of a total of about 9 could be spotted by the audience. This was held as proof that elephants could not be accurately counted and that any attempt at a census would result in unacceptably high bias. Dr. Ferreira conceded that he has not undertaken a helicopter census of elephants.
The above perception was somewhat refuted by Dr. Ferreira and the discussion revolved around concepts such as accuracy and precision.
I joined Dr. U de V Pienaar’s helicopter census team from its inception in 1966 and participated annually until 1986. The major features of the census were the following:
§ it followed a standardized process, i.e. covered the entire Park by means of fixed routes and at the same time of the year;
§ it was undertaken from mid-August to mid-September, a period coinciding with the driest time of the year when surface water resources were restricted, deciduous trees had lost their leaves, visibility was at a premium and the animals were most concentrated;
§ the census team consisted of 4 observers, the pilot and an observer/navigator in the front seats and an observer/photographer (for many years primarily my role) and an additional observer, usually the section ranger, on the back seats.
§ the only factor over which there could be little, or no, control, was the weather. Poor weather conditions, especially low cloud and cold winds associated with cold fronts, could negatively impact on visibility and therefore result in some animals being missed. Such conditions at the end of the winter season are, however, infrequent and usually do not last more than a day or two.
Elephants are easily spotted from the air in virtually all the landscape types of the Park. There are no extensive evergreen forests or closed-canopy woodlands of any consequence where it would be difficult to spot elephants. In addition, elephants are generally wary of the whine of the turbine engines of a helicopter and move when approached, thereby making spotting easier.
When breeding herds of elephants are approached they generally bunch together and are difficult to count. However, with some deft maneuvering of the helicopter the herds are easily scattered, and the herd animals can then be counted to the last individual. Bulls pose no problem. In this way a highly accurate count of all the elephants spotted can be obtained. It cannot readily be estimated/guessed how many elephants are missed during the census though factors such as maximum visibility, restricted water resources and the design of the census routes contributed to a high likelihood of spotting the animals. It is confidently believed that for most years very few animals were missed and that the accuracy of the census results was high (see Ian Whyte: comment 1).
To obtain a count from which statistically determined confidence limits can be estimated at least three counts need to be completed, preferably in quick succession. This would not be financially feasible nor practical in terms of the entire Park. However, if precision is really such a high priority repeat sample counts in each of the 4 regions of the Park could be undertaken in conjunction with the annual census. This could be financially and practically possible and probably required for only one year. On the other hand, the highly comparable census totals for the Park over more than 40 years should surely instill enough confidence to render them scientifically accountable! At least, the results reveal a high degree of repeatability – an aspect which is also of crucial importance.
The question of the accuracy and precision of the census results is an aspect that received much consideration over the years and is addressed in the respective census reports.
Censusing wild animal populations includes data collected on population trends, distribution patterns and social organization structures (plus a host of important associated information). As such, censusing animal populations remains one of the most essential support projects in wildlife management. Its value in terms of monitoring and interpreting ecosystems should not be underestimated!
Censusing may even have quite unexpected outcomes. In this respect the following interesting bit of information recently came to my notice from two quite different sources: a herd of sable antelope (apparently 30-something) were released into a large enclosure in the Marakele National Park. In an aerial census of the enclosure only something like 3 animals were counted. The first reaction was to deride the census figure (rather heftily, I believe); a repeat census yielded the same figure. It was only later discovered that poachers had entered the enclosure, caught the bulk of the sable and made off with them!
On an aside: I believe that buffalo herds are no longer photographed as part of the census but their numbers merely ‘estimated’. As incredible as this may sound, can it possibly be true?!
And as far as the other large herbivores are concerned: personally, I do not believe that the time, manpower, money and effort put into the ‘distance sampling’ method of censusing the other large herbivores is of any value to the Park. The initiators of the method, Drs. Anderson and Burnham of the Colorado State University, USA, were in the Park, taken up in the aircraft for a simulated count and advised us that the method was not suitable for the Park. I have on occasion written to Dr. Mabunda and suggested that it is time for a proper census to be done of all the large herbivores of the Park, to the same standards as those done earlier and I feel the need to repeat this suggestion again, as a matter of urgency.
‘Event-driven’ elephant management
I hope my interpretation of ‘event-driven’ is not too simplistic but as I see it this mainly implies that cues are derived from the level of utilization of the vegetation and that impacts exceeding predetermined ‘thresholds of concern’ need to be addressed. If this is correct I have certain areas of concern that I would like to raise:
§ Dr. Ferreira intimated that the Crocodile River area needs to be addressed. What I would like to know is: how was this determined and what has made it a higher priority than several other areas that I am aware of? Is any report/publication available which details the criteria to be applied to determine areas of concern and, in this particular case, what is(are) the motivation(s) given to select this area?
§ In 1988 a former botanist of the Park, Albert Viljoen, published a paper in which it was shown that 93.4% per ha of the large trees (mainly knobthorn and marula) on the basalt plains south-east of Satara had disappeared between 1944 and 1981. Similarly, 49.6% of the trees (per ha) on the basalt plains between Lower Sabie and Crocodile Bridge had disappeared in the corresponding period. Has any follow-up work been done on this?
§ To determine the events, and their intensity, to guide decisions on elephant management automatically implies that considerable effort will have to go into vegetation monitoring and assessments. In this respect questions arise such as: does the Kruger Park even have a botanist on its staff (as far as I have it no-one has been appointed to replace Holger Eckhardt, who resigned some two years ago!); have any analyses been done of the large number of fixed-point photographs (roughly 500) taken since 1977, or the large-scale aerial photo transects (more than 120) taken since 1981 (are they still being taken?); or the effects of the out-of-season veld fire program presently implemented? How will these projects be undertaken if research officers, as incredulous as this may be, are restricted to only 30 days field work per annum? I believe there is a student analyzing vegetation trends from satellite images but whether this will be sufficient (detailed enough) to give guidance on elephant management strategies is doubtful, at best.
The big question is: can the Kruger Park really convince the scientific and public audiences that the defining and prioritizing of the ‘events’ to serve as guidelines for the implementation of elephant management strategies are, indeed, scientifically accountable? The counter-question is even more to the point: can the option of no-culling be justified while there is an apparent total lack of research capacity to cope with surveys to determine their impacts?
Areas heavily utilized by elephants, to the point where some management intervention is required, implies that those areas are attractive to elephants. By what manner and means are elephants going to be denied access to the areas, for how long and where will they be going to in the meantime? Have these practicalities been addressed? Is culling regarded as an option?
Spatial and temporal considerations
Spatial and temporal aspects play a vital role in the health of all animal populations and are intrinsic components of natural processes. Disruptions of the spatial and temporal rhythms have had severe impacts on several populations of the Park, e.g. the erection of the western boundary fence of the Central District that severed the migration routes of especially wildebeest and zebra and caused major collapses in these two populations. Similar disruptions have resulted in the local extinction of roan antelope and also affected eland, amongst others.
Spatial and temporal considerations, in fact, have been integral in formulating the principle that provided direction in deciding the justification, or otherwise, for the manipulation of animal populations. In cases where it was believed that the full population cycles of species could be accommodated in harmony with the fluctuations imposed on the other components of the ecosystem by the medium (20 year) climatic cycle, and without being affected by any man-induced disturbances, there was no justification to interfere with those populations. This led to the termination of culling in all but the elephant and buffalo populations. In the case of these species it was believed that the spatial constraints of the Park were severe enough to induce artificially high densities, to the ultimate detriment of the other components of the ecosystems. This ‘ultimate detriment’ was interpreted as artificially induced disturbances to the structure and composition of the other components, e.g. vegetation and animal populations (including species mix, numerical status and spatial and temporal disruptions). These effects would inevitably also affect other taxa, such as insects, reptiles, birds and small mammals. Artificially high densities of species constrained by spatial limitations could, therefore, have an impact on the total biodiversity of the Park.
Elephant, obviously, fell within this latter category. They could adapt to virtually all the habitats in the Park, their population trends were not affected by the medium term climatic cycles and they were highly competitive for the vital resources of food and water. From the history of the population trends it was also obvious that the Park was too small to accommodate their expanding population. To address this situation, it was deemed imperative that some form of control of their numbers had to be exercised. The only option was to dispense with what was considered to be excess numbers. This was achieved through live translocations and culling. In this manner a remarkable level of control could be exerted over the population.
One of the fundamentally important attributes of all forms of ‘life’, at whatever level of organization – whether at individual, population or ecosystem level, is that all functions (natural processes) are fulfilled by way of rhythmic cycles. The elephant population is no exception and one of the major challenges in the management of elephants was to find a way of imposing such cycles on the population. This is obviously a largely impossible task, considering that elephant population cycles, according to the best data sets, take anything between 200 and 400 years to complete. Nevertheless, the consequences of this are that elephant at stable levels probably exert a greater cumulative impact on the environment than heavy impact over a relatively short period, a collapse in the population and then a relatively long period (several medium term climatic cycles) for the habitats and associated species to recover.
Dr. SCJ Joubert
5 October 2010
Dr. Salomon Joubert is the ex-director of the Kruger National Park in South Africa and spent 40 years in the service.