An examination of the permanent range of elephant (Figure 8) indicates subpopulations in the east and the west of northern Namibia. The separation is not so rigid as to create genetically isolated subpopulations since the 'occasional' range of elephant links the two and there is a small resident population of about 20 animals within the 'occasional' range in Mangetti Game Reserve. Each of these subpopulations can be subdivided into two parts (which have been surveyed as separate areas over the past thirty years):

In 2004 the total population was estimated at over 16,000 animals and, allowing for underestimates on air surveys, the true number in 2005 is likely to be closer to 20,000. The north-western population appears to be growing at about 3.3% per annum and there are movements of elephants in and out of Etosha. The recent increases in the north-eastern population are well in excess of normal growth rates (which are less than 5% per annum) and must be attributed to immigration from the northern Botswana population (about 150,000 elephants) and the north-western Zimbabwe population of (about 50,000 elephants). The huge number of elephants south of the Caprivi presents Namibia with a management challenge.

Summarised Elephant census data and estimates for Namibia are available in pdf format.

Migration

Lindeque (1988) has pointed out that a single regional population occupies Etosha and the North-west and that migrations in and out of the park take place continuously.

There are only three occasions since 1966 when surveys have been conducted in all four of the subpopulation areas in the same year, i.e. 1986, 1998 and 2004 (Table 4). Martin (2005) used a simple population growth model to find a best fit for these three data points with a starting population of 827 in 1966 growing at a rate of 8.173% per year(Figure 16). Since this exceeds the maximum intrinsic growth rate of an elephant population, it must be presumed that immigration has taken place. Similarly for the populations in Caprivi and Khaudum/Nyae Nyae, it has been found that the inclusion of a significant degree of immigration is necessary to obtain a reasonable fit to the estimates.

To improve the model, three additional estimates have been added by including interpolated values for the Caprivi in 1984, 1990 and 1995, when partial surveys were done. An inspection of the first four estimates (1984, 1986, 1990 and 1995) suggests that very little change took place in the population during this period and that immigration only took effect after 1995. In order to establish a starting population for the model, the initial iterations were limited to these four data points and, assuming a population growth rate of 4% (being a compromise between the best fit value of 3.3% for Etosha and the assumed 4.6% for the north-east), an initial population 2,770 animals in 1966 was established.

Using all six estimates, iterations were then performed to obtain the optimum values for the year in which immigration began, the number of animals immigrating in that year and the rate of change of immigration in the following years. A best fit was obtained with an initial immigration of 194 animals in 1996 followed by immigration increasing at a rate of 23% for every year thereafter. Were immigration to continue at this rate, the Namibian elephant population would exceed 18,000 elephants in the year 2005.

This model must be treated with caution: it has already been established from the individual subpopulation models preceding this overall analysis that each subpopulation has a different history and displays different characteristics. Therefore any attempt to model the overall population is at best a compromise of these characteristics. However, if there is any validity in the finding that a process of substantial immigration is underway at the moment, then this must become one of the primary challenges for Namibia's elephant management plan.