Cape leopards roam massive territories in the rugged mountains of the Western, Northern and Eastern Cape. In order to better inform management plans and conservation strategies for this species, we need to learn more about their habitat requirements and movement patterns, and sometimes this means fitting GPS satellite collars to certain individuals. However, the collar should not stay on that animal for the rest of its life. Modern collar technology allows for automatic release mechanisms (called drop-offs) to be built into the collar belting, allowing the collar to “drop off” after a specified duration of time. This is of course ideal because it eliminates the need to recapture that specific animal to remove the collar. The downside of these pre-programmed drop-offs is that the researcher has no control over where the collar falls off… It could happen anywhere – and this of course adds a whole new meaning to finding a (very small, brown, inconspicuous) needle in a (very rocky, very steep, very mountainous) haystack…
One such recent collar retrieval mission was particularly exciting because it involved a helicopter flight and an epic hike to a stunning location… A female leopard called Chloe, who roams the mountains between Gordon’s Bay and Rooiels, dropped her collar just before Christmas 2013. We tracked the collar via its VHF radio signal and were very fortunate to pick up the signal around Koeël Bay, en route to Rooiels. It was clear that the collar was lying in a difficult place and was struggling to communicate with the GPS satellites, because it had not taken a successful GPS reading since the drop off. We could therefore not pinpoint the collar’s current location using GPS coordinates. From the VHF signal it was also clear the collar was somewhere very high up, and we knew that we would have quite a search mission on our hands… We decided to launch “Operation Collar Search” in the new year…
In January we tried once more to download GPS data off the collar, and lo and behold, it had managed to take a GPS reading during the previous week! This was good news, because we now had coordinates to navigate to. After plotting the point on Google Earth, we were quite excited, because if the GPS reading was correct the collar was right on top of the Blousteen mountains above Koeël Bay. This would either mean an overnight off-trail bundu-bashing hike through the Kogelberg, or flying in to the spot with a helicopter to pick up the collar – if we could find a willing pilot! Both prospects seemed very exciting, and we decided to try the helicopter option first.
We were very lucky to find not only a willing pilot but also a sponsored flight, and on a clear Saturday morning in late January we were en route to Blousteen, with Guido Costa in his Alouette II helicopter! We flew to the exact GPS location, and after a rather technical landing, we started searching for the collar. However, we were very concerned – we weren’t picking up the VHF signal from the collar at all. This either meant that the VHF battery had died (which was extremely unlikely), or we were in the wrong place… Nonetheless, we searched around the GPS point for about an hour before having to call it a day – the wind was becoming stronger and we were quite eager to get off the mountain… We were of course very disappointed, and Guido kindly offered to also fly around the mountains to see if we could perhaps pick up any signal on the other side. We were about to give up when we finally heard a faint beep beep beep… On the one hand this was great news because it meant that the collar was still transmitting VHF, but on the other it meant that the collar had taken a false GPS reading and it was obviously not where we thought it was… This was probably due to the difficulty it was having in communicating with the satellites, and by some glitch it registered a false reading… The slopes where the signal was coming from were way to steep for a chopper to land – we would have to hike in. So we had to return home empty handed – but at least the helicopter ride had saved us the trouble of an overnight hike to the wrong place!
The following week we returned once more to Koeël Bay, now armed with the knowledge that the collar was certainly on “our” side of the mountain, and not on top as we had initially thought. The one thing that makes VHF telemetry in the mountains very challenging is the fact that the signal gets “bounced” off surrounding rock faces and peaks, which can make it rather tricky to pinpoint the exact direction. You also need to be in line of sight of the signal transmitter (i.e. the collar) in order to pick it up, so in mountainous terrain it is very easy to lose the signal. We now had to rely solely on the VHF signal to lead us to the collar, and using a handheld directional antenna we started our trek up the mountain.
It was a hot, very humid day, and the signal led us ever upwards. Going was tough through the thigh-high vegetation and clambering over rocks. Once we were sure of the direction, we still weren’t too sure about the height – which is difficult to determine on a very steep slope. And so we climbed, up and up and up, until we got to the point where we could go no higher – the cliffs were becoming too steep… The was a big cave right above us, and from the signal strength we knew that we had to be extremely close – within 15m – but 15m on a vertical cliff face can be a lot! It was Anita who peered over the one little ledge and excitedly started shouting – There it is! There it is! There it is!! The collar was lying neatly on a patch of soil surrounded by some succulents – almost as if Chloe had purposefully left it there for us! We were elated!! The sight of that small brown round thing made the long hot ascent worthwhile 10times over! But what goes up, must come down, and we started the long trek back to the bakkie, which at this point was just a tiny speck in the distance. With creaking knees and burning feet we eventually plopped down in the shade of the bakkie and gulped down all the water we had left in the car. We drove back home feeling exhausted but extremely happy, and that night we slept like the rocks we were climbing over for most of the day!
Thank you very much to Guido Costa for his skilled flying (and landing!), and for saving our knees from a very long futile hike!
Jeannie & Anita.