The present status of waterbuck and puku appears to be that of occasional visitors from Botswana. Introductions of substantial numbers of these species could produce the desired resident populations. Population numbers seem to be linked to variations in the cumulative surplus/deficit in rainfall.

Reedbuck

In 1975 there were no more than 50 reedbuck in the country (Joubert & Mostert 1975). The species was recorded in modest numbers from 1978 to 1994. From 1995-2002 concerns about the status of reedbuck were expressed. Unfortunately, there have been few surveys of the Caprivi since 1995 so that there is little comparative data - however, it would appear that higher numbers were recorded in the period before 1995. In particular, a fairly comprehensive survey in 1998 yielded an estimate of only 34 reedbuck, all in Mahango (none were seen in Mudumu and Mamili). Reedbuck are probably present in higher numbers than the survey data indicate and, given a favourable rainfall and fire regime, could easily reach the expected numbers.

Table 9: Summary of Population Numbers

Red Lechwe

Lechwe have been recorded in large numbers in the recent past (13,000 estimated in 1980) and, if habitat conditions once more become favourable, they could rebound. Estimates of lechwe numbers (Figure 18) were consistently higher than 4,000 up until 1995. After 1996, the long term rainfall moved into a deficit mode and the lechwe population appears to have crashed.

Private land

There are substantial numbers of reedbuck, waterbuck and lechwe on private land in Namibia. Although the introductions of reedbuck are not condoned by the Ministry of the Environment, the species is 'relatively numerous on private land outside its natural range' (ASG 1998). There are some 3,500 waterbuck on 63 commercial farms (Figure 20). The apparent ease with which these populations have been established outside the historical range for the species (the largest farm population is 400 animals), suggests that an injection of waterbuck into the Caprivi parks and conservancies would stand a high probability of success. There are over 200 lechwe on 15 private farms (Figure 21). If reedbuck are deemed unsuitable for introduction to commercial farms in the main body of the country, then lechwe must be seen as being even more unsuitable. It is doubtful if there is any 'classic' lechwe habitat on any of the farms where they presently exist. However, perhaps such introductions should be seen as research experiments: if these lechwe survive in the long term, questions will have been answered and new questions will arise. Much of the dogma surrounding ecological requirements for the species will need to be re-examined.

Data Quality and Interpretation

The Namibian data are not very valuable for comparative purposes or for detecting trends because the same areas have not been surveyed consistently from year to year and because of the variety of survey techniques which have been used on different surveys.The types of surveys which have been carried out include waterhole counts, total counts from fixed wing aircraft, total counts from helicopters and sample surveys based on line transects with calibrated strip widths. At present there is no acceptable alternative to the standard transect survey method or the random block count method. Systems which rely on "total counts" or "actual observations" are statistically inferior because no accuracy or precision can be attached to the estimate.

The data for reedbuck and lechwe from surveys carried out in the Caprivi since 1978 (Figure 17 and figure 18) need to be treated with some caution and the observed swings in population numbers may be no more than artifices arising from irregular and incomplete surveys. The apparent declines in reedbuck and lechwe numbers seem real, however, because no estimates made in recent years approximate to the numbers which were seen in the 1980s.