Kelp Gull Project: Gone batty

Rob Raw, a PhD candidate from UCT needed field assistance at De Hoop Nature Reserve working on bats. With my fieldwork done I was keen for some different experience and agreed to join him for 2 weeks. It was indeed an experience working with these amazing little creatures! His focus for this trip was Geoffroy's horseshoe bat Rhinolophus clivosus. I arrived on Monday evening, joining Rob and his girlfriend Alicia to bring the team up to three, and straight after supper got stuck into one aspect of my job, feeding the bats. The bats were kept in a flight room in the research house which had a heater and a humidifier to keep the bats in a more natural roosting environment. Rob would go into the room and catch the bats and our work began. Bats were sexed, weighed, and had a wing measured before being marked using nailpolish on their claws; then it was time for food and experimental trials! These little guys are insectivorous and they were fed a steady diet of mealworms. A starter of 10 mealworms before the trials began, a snack of 10 mealworms midway through the trials and then an eat-as-much-as-you-can buffet of mealworms once the trials for the night were done. Depending on the bat, they could eat easily being held in the hand, or they could close their mouths and turn their heads like children refusing to eat vegetables, going so far as to spit the mealworms out! But to get an individual which would eat with gusto was wonderful! They would stuff their cheeks like hamsters, except their cheeks are not meant to be stuffed! They could become vicious little jack russels, snatching the worms from the tweezers and chewing with gusto! The sound made while chewing, a grating of teeth, added to the vicious image. We had up to 9 bats at the house at a time and, depending on the bats, it seemed to be a continual rotation of feeding. While we were feeding there was a bat undergoing trials. This aspect of Rob's research was focussing on behavioural reactions to artificially created versions of their calls, shifting the pitch or other aspects of the species call. How late we stayed up working all depended on the bats: whether they ate easily and how quickly they settled in the chamber Rob used for trials. In the chamber was an infrared camera which allowed him to watch them, he needed to wait for them to settle in the chamber before trials began and sometimes he could wait more than 30 minutes while they groomed! I really enjoyed watching them groom, they are very sweet little creatures! As a result, bed time could be anywhere from 9pm to midnight, but we had the entire day to recover, and explore the reserve, while the bats slept before trials began again.

Geoffroy's horseshoe bat.

Oh no! See the painted nails..

Weighing the bats.

Omnomnomnomnom!

Lots of mealworms!

The other aspect of my job was to help Rob catch the bats. We went to the cave every third day which I must admit was the best part of the trip! Getting to the cave was no simple matter. First a 45min 4x4 drive bouncing around, then a serious paddle with all the gear in an inflatable rafting boat of sorts and finally a short but steep hike to the cave entrance. Once there we tended to spend a moment gathering ourselves and preparing the gear. Going into the cave we had to wear respirators due to a fungus that grew in the cave, and so we tended to sound like Darth Vader, added to that we moved in the cave using red light as it disturbed the bats less, so I could imagine giving anyone who may have stumbled across us quite a scare and as highly unlikely as this was it did keep me highly entertained! As amusing as I thought we looked and sounded it was not a comfortable get-up. Moving through the cave that first day was surreal, not being able to see quite clearly and breathing through the respirator was very strange. The cavern where we caught the bats was quite a trip into the belly of the cave, and it was not a simple journey. There were areas where I was squatting down waddling through smaller tunnels - I hadn't thought to bring long pants to wear in the cave and I was not keen on putting my knees down on a guano covered floor to crawl through the tunnel! All the while as we missioned deeper into the cave were bats flying around us, sometimes in large numbers but sometimes just one or two. Another factor that I had not really expected was the humidity! The only other caving experience I had was at Cango Caves which was quite cool. Guano Cave (named for the guano mining that occured there many years ago) was hot and humid! Rob had once measured the humidity in the cave and it was around 99% and did I feel every little bit of it! Once we reached the cavern where we caught the bats I was covered in sweat. Rob caught the bats using a butterfly net as they dropped from the walls with our presence disturbing them and I stood ready to bag them as he checked they were of the Rhinolophus genus. As we turned around and started the trek back to the cave entrance it often felt as though someone had turned the aircon on. As hot as it may have been outside it was nothing compared to the humidity in the cave and it was so refreshing to reach the cave entrance and pull the respirator and headlamp off my sweaty face. Before we could begin the trip back to the house we had to check the bats we had caught. We may come out of the cave with a good haul of bats but we couldn't take them all home. There are two species of Rhinolophus that live in the cave and they look identical, the only way to tell them apart is by their calls. Rhinolophus clivosus (the bats we wanted) echolocate at a frequency of 85 kilohertz while Rhinolophus capensis echolocate at a frequency of 92 kilohertz (on average). Rob used a handheld detector that picked up the echolation calls of the bats and so we separated the two species, thinning the number of bats we had to take back. This number was further dropped by checking that all the bats were adult (done by looking at wing bone fusion) and checking that none of the bats had nailpolish on (we didn't want to take bats that had already been through the trials). Bats were taken back to the house and that evening was the first night of trials, and the second night after trials they were released. We got back to the house filthy and after releasing the bats had a shower and lunch, and it is amazing how the simple pleasures of a hot shower and food can revive a person!