Survey and monitoring activities
The Survey and Monitoring Unit is responsible for game counts, whether they are done from the air, on the ground or from a hide at a water point. This also includes regular biannual bird counts at the important Namibian wetlands. Often the unit is dependent upon other colleagues or the public to help with the counts. Up to several dozen volunteers help with the bird counts. Some counts are specialized or still experimental and are conducted by individual researchers, not directly linked to the survey unit.
Staff in Namibia’s protected areas is encouraged to conduct routine monitoring in their area.
Stratified sample counts – Sample counts are done in large areas for populations of animals for which one can expect to see a reasonable number of individuals. For example, in the Etosha National Park sample counts work well. The park is subdivided into manageable units of about 15 blocks. Blocks should not be too big, so that one can sample these blocks by transects covered by an aircraft in 10 to 20 minutes. If the transects are too long the observers lose concentration. The blocks should have a uniform density of the animals to improve the precision of the calculated estimates. The accuracy of the estimates is a function of how easy the animals can be counted from the aircraft. Animals such as kudu, although relatively big, stand still when disturbed by an aircraft and blend in well with their surroundings making them difficult to count from the air. In contrast, wildebeest generally feed in the more open areas and scatter at the sound of an aircraft, making them easier to count.
Stratified sample counts refer to sample block counts were the intensity with which each block is counted is adjusted based on the expected game densities and required precision. Etosha is counted at approximately 25% coverage and an aerial stratified sample count takes about 2 weeks to complete.
A big park like Etosha is only counted every second or third year. Smaller parks that are also managed intensively are counted annually. Whereas the relatively open are of Etosha are counted from a fixed-wing aircraft (normal aeroplane), more densely vegetated or smaller parks such as the Waterberg are counted from a helicopter. The helicopter allows for more accurate transect flying and small parks are then counted precisely as sample counts would provide very imprecise estimates based on the small population samples.
Aerial censuses were started in the early 1970s in Namibia’s parks. The Super Cub aircraft with space for the pilot and one observer was initially used. Today, the larger Cessna aircraft are used as they have enough margin for safety to fly at a low altitude. A pilot, a navigator/recorder and two observers man them. The plane is generally flown at 50m above ground level and a 200-250m strip wide is searched on either side of the plane. While in the beginning blocks were searched using paper maps, today GPS are used in order to guide the aircraft along transects and to record the actual flight path and all sightings.
Stratified sample block design for Etosha, showing individual transects
Detail of transects with actual observations within blocks
Aerial census methods are today quite technical and require experienced personnel. They are thus not very inclusive.
Ground counts, done from a vehicle or on foot, have been used successful over the last decade especially in the Kunene conservancies. These counts involve many different observers and counting teams. Figures obtained therefore have a lot more buy-in from the field staff, considering the fact that these are essentially their own figures. Because vehicles move much slower than aircraft, the more cryptic species are picked-up more easily. However, it is a lot more difficult to cover an area systematically. Generally roads cover flat open terrain or follow interesting habitat. Several species also tend avoid the area immediate to roads and are thus underrepresented in road counts. This is especially the case where animals are hunted from the roads.
Waterhole counts
In areas with a limited number of open water points, at least during the dry season, water hole counts are another alternative way to count game. Again this is a participatory method, requiring many observers. Generally all waterholes in a particular area are observed simultaneously for 48 or 72 hours. Often waterhole counts occur around full moon when there is greater visibility for observers. All animals are recorded and where possible any distinguishing features are noted in order to reliably identify animals that come and drink more than once. Kudu that are very difficult to count from the air can be counted relatively easily at waterholes. Kudu come and drink mostly during the day, and with some experience individual groups can be distinguished.
Areas counted since 2000 by means of aerial censuses
Camera traps are used to get population estimates for species that can be identified individually based on spot or stripe patterns on coats but which are otherwise difficult to count, such as leopard. Camera traps can also yield interesting distribution records for rare or cryptic species.
Spoor counts across roads have been used successfully to estimate predator densities.
Individual identification – rare species or those with unique identifying features are routinely counted through the identification of individuals, mostly through photographic identification. Rhino or small populations of giraffe are counted in this way.
Eight buffalos