Because of fences, animals in reserves are unable to migrate as would have occurred naturally according to the seasons or predation pressure. Managers need to know how the animals are behaving in order to manage the system so that it operates as if it were open. In the small enclosed reserves it has been suggested, with lion populations especially, that a minor management decision could have a large impact on the reserve ecology. The types of prey that the lions take will also affect the prey populations and the reserve ecology.
This detail of the lions is what us EMs are involved in, but me being me wanted to see how this fitted into the bigger picture – the ecology of the reserve. How the lions impact on prey species. What are their preferential prey species? What other research is being done? How long do they expect the antelope to adjust from running from vehicles (associated with hunting, which stops this month) to becoming habituated to vehicles (rather useful for eco-tourism)? (Interesting tangent, while we were out yesterday we saw a large herd of impala. Some took off when they saw the vehicle, some didn’t. Christo got out, they weren’t too fussed, but as soon as he raised his arms as if he was raising a rifle they were off.)
So… how do we go about finding them? We have a map of the reserve stuck to the wall, with different coloured pins for each collared lion. When we go out on each drive, we check this map first and then check for the lions from the highest point on base and if we get signal we take a bearing which is then used to give us an indication of which part of the reserve to go to.
The analogue telemetry set consists of a control box with an antenna. First we check for signal vertically (gives us a general area where the lion is located) and then we check for signal horizontally. Each collar responds to a different channel and frequency. With the antenna horizontal it is possible to wind down the frequency giving a indication of direction and distance for that particular lion. Once we can wind down the frequency below 0 then we know we are probably within a few tens of metres or so from that animal. When we have signal at a frequency of -2 to -3 we can start looking for a visual of the lion and if we get -5 then we’ve probably run over it. For example, Tsotsi is on channel 2 at a frequency of 2. At this frequency, you might get a wedge from 12 o’clock to 3 o’clock. Turning the frequency down narrows the width of the wedge and fine tunes it.
Once you’ve decided on the direction of the middle of the wedge – say at 1:30 then you check for back signal at 180 degrees to where you think it’s coming from. Whoever is on telem stands on the back of the Mehindra to gain as much height as possible. They then check vertically and horizontally and then wind down the frequency to determine the direction. Once -2 is reached, we’re no longer allowed to stand up – it’s now mobile tracking – either sat or lying down (see previous post) while holding the antenna up with one hand.
Once you’ve identified your direction you then take a compass bearing remembering to take 12 degrees away from the compass bearing to give you the true bearing.
While the telem person does all this the data person in the cab is noting down the GPS co-ordinates in order for the triangulation person to plot our location on a laminated map. The reserve lies 22 degrees south and 29 degrees east and the GPS records in decimal degrees. We have conversion charts to convert the decimal degrees to millimetres so we can actually plot our location on the map. A protractor is then used to draw an accurate bearing on the map and the frequency at which that bearing was taken is also noted (for example, Ts 234 degrees at +2).
Sometimes we stop in various places to get 3 bearings – when these are plotted they should all cross each other giving a perfect triangulation point (TP). This is done for the jackals as they are very hard to spot and likely to bolt underground and also if any of the lions are in exceptionally hard places to get to. The TP point is then converted back to decimal degrees and written on the data sheet which is then put into excel.
At the end of each expo, this data is collated and plotted – but first needs to be converted from decimal degrees to metres before being plotted accurately in ArcView 3.2. The maps produced are then used to write up a scientific report for each expo. An annual report is also produced (the first will be at the end of 2007).
The point locations of each lion (visuals or TPs) are analysed to produce 95% kernels and 50% kernels. 95% reflecting home ranges and 50% for core ranges. Data is being built up for any opportunistic sightings we have of uncollared lions, black backed jackals, cheetahs, spotted and brown hyenas, rhinos (black and white), leopards, wild dogs, elephants, bat-eared foxes, African wild cats, caracals, honey badgers and small spotted genets. We haven’t been fortunate enough to see all these animals but we have seen some. And you never know, we might spot something between now (Sunday 11th) and the end of tomorrow (our last drive).