Khaudum National Park and Nyae Nyae Conservancy

The earliest surveys of Khaudum were in the mid-1970s when numbers were less than 100 animals (Figure 14). Survey areas have altered over the period 1977-2004 and the later estimates include areas outside the national park and the conservancy. As the elephant population has increased larger and larger areas have been included in each survey. Although this section is titled "Khaudum National Park and Nyae Nyae Conservancy" the data should be taken to include all elephants in the eastern part of Kavango and Otjozondupa provinces.

The most recent surveys estimate the eastern Kavango population (including Khaudum) at slightly less than 4,000 animals (Kolberg 2004) and the eastern Otjozondupa population at almost 1,000 animals (Stander 2004). Numbers such as these could not have been achieved through normal population growth. Martin's model (2005) suggests that a starting population of 80 animals in 1977 would have reached less than 300 animals by 2005 growing at a rate of about 5%.

Martin (2005) used the model to find the amount of immigration needed to best fit the population estimates. He assumed that the population grows at 4.56% and that all the population estimates need to be increased by 25% to approximate the true numbers in the population. The initial population in 1975, the initial immigration and rate of change of immigration have been simultaneously iterated to obtain the best fit. This is obtained with a starting population of zero in 1975, an initial immigration of 34 animals and in each year after 1975 the immigration increases by 7.14%. This implies an annual immigration in the year 2004 of 251 animals.

The Caprivi

The estimates for the Caprivi population are given together with alternative population models for the period 1977-2004 (Figure 15). A feature of the data is the number of years with incomplete surveys - making it difficult to develop robust population models.

Despite the 'noisy' nature of the data, the best fit to the series of estimates is a scenario where the population declined from 1977 to 1989, a major immigration of animals took place in 1990 and, since then, the population has increased at normal growth rates to reach its current levels.

The most recent estimate for the population is 8,726 animals (Kolberg 2004). In 2003, Griffin & Chase (2004) estimated the population at 5,740 animals and, taking these two estimates in isolation, it would appear that some substantial recent immigration has occurred.