Knowing that large mammal surveys are an essential part of the necessary resources inventory and will play a key role in all long term monitoring approaches in the reserve; knowing that large mammals are particularly important as key factors in the ecosystem and can potentially be very useful as indicator and umbrella species to focus conservation and management efforts, SRN used some of its limited resources to address what was considered a priority: to obtain valid information on wildlife, particularly on large mammals. With this objective in mind, three aerial wildlife surveys have been undertaken in the area, in October 1998, October 2000 and October 2002.
In all cases, an area of 42 341 km2 was covered, including the adjacent buffer zone/hunting blocks. The surveys employed the technique of stratified systematic transect sampling (Northon Griffiths 1978) from a light aircraft flying at a nominal height of 300 feet above ground level. The sampling intensity was increased from an average of 8% in 1998 to 10% in 2000 and 2002, to improve the precision of the estimates.
The aerial surveys, focused mainly on assessing for each of the major species, the population size (estimates with a 95% confidence range), as well as their density distribution. The estimated numbers and densities of animals are given for each of the regions within the survey area, as well as the overall totals. Information about the number of carcasses on the floor and their characteristics (old or recent poaching activity), was also provided. For comparison purposes, all aerial surveys were performed during the month of October, the pick of the dry season. This permitted to obtain some level of information on trends between surveys either with respect to population sizes as well as to poaching activity. Moreover, the aerial surveys provided notes on human occupation by recording the positions of villages and fields to monitor possible increase in settlements. Within the area it can also assist establishing where illegal hunting might take place, as records of the positions of the snarelines were also taken. Information about the fires, their characteristics and potential impacts was also included in the final reports.
SRN is keen on continuing to perform an aerial survey every two years making it possible also to cover the sample frequency statistical requirement.