Field work continues to be a strong component of my work. Not only is it the raw source for much of what I later work with (specimens, ecological, life history and behavioural data), but more importantly, it is also the source of insight and inspiration. Here are some impressions from my most recent trips to Africa.
Communicating with Carpenter Bees
Semiochemicals: chemicals used by organisms for the purpose of communication. Never heard of them? You certainly have, but under different names... Pheromones are in fact a type of semiochemical that are used to communicate with members of the same species. But there are more. Organisms can also communicate between species using chemical cues. Flowers for example, smell nice because they want to attract pollinators. The chemicals produced in this scenario are often called allomones because they are beneficial to the originator, but they may also act as kairomones, which are chemical cues that are beneficial for the receiver, that is, IF the flower provides a nectar reward.
So why is any of this worth traveling to Kenya for? Well, imagine you want to introduce GM crops or a pest resistant strain of a particular crop plant like Cowpea, a widely cultivated legume in Africa. What you definitely don't want to happen is for that resistance to spread to wild-type con-specifics. So somehow you have to stop the resistant plants from reproducing with the wild-types. If you could understand the cues that the resistant plants are signaling to pollinators and disrupt that communication, so that pollinators can no longer locate plants, or simply find them unattractive, then you could you could effectively stop hybridization with wild-types. These are the kind of practical applications that Jette Knudsen and her fellow chemical ecologists are working on and I was fortunate enough to hitch a ride.
After touching down in Mombasa, it was only a short drive to Diani Beach, where we set up shop. Not a bad spot!
...although we did have some uninvited guests over for lunch
The actual field work was conducted at Muhaka Field station, a stretch inland from Ukunda, in partnership with ICIPE. Our goals were two-fold:
1) Collect Cowpea floral scents, for chemical analyses back at Lund University in Sweden
this is more or less straight forward. You wrap flowers in oven bags (really good because they release no chemicals) puncture two holes in it on opposite sides and connect special filters. Attach one of the filters that will suck air out of. Air going into the bag will be cleaned through the first filter, and any chemicals produced by the flower will be trapped on the second filter going out. This second filter we will then process in the lab.
2) Learn more about the foraging behaviour of Xylocopa carpenter bees, one of the key pollinators of Cowpea.
This was a simple choice experiment. Are carpenter bees attracted to only the striking purple colour of the cowpea flower or its scent? After catching these clumsy bumblebees, we set up a board with equally spaced holes in it where we mounted flowers in covered in plastic bags, half of which had holes in them. This way, there were flowers with just the visual cues, and flowers with visual and scent cues. The board, the observer and the bees were then all crammed into a 3x3x3m meshed cube and the visitations of the bees were recorded.
Most of the field work had to be done at sunrise. this meant we had an extremely early start, but that also left the afternoons to explore the Kenyan coast line a little bit. One afternoon we even had time to drive a few kilometers inland to visit Shimba Hills National Reserve!!
The Land of a Thousand Hills
They call Rwanda the land of a thousand hills, and they weren't kidding....
It's one of the smallest country in Africa (smaller even than most European countries, clocking in just behind Belgium), that unfortunately has one of the most devastating recent histories. The genocide of 1994, was one of the most brutal the modern world has seen and one the international community has to bear the cross for in many respects. This particularly dark chapter in Rwanda's history has also had an effect on the wildlife. With people being driven out of the cities, many settled in villages and camps in the forest where logging for firewood and hunting has lead to the local extinction of some of Africa's most characteristic animals. Once full of Elephants, all that remains now in Nyungwe National Park is local names that remind us of their former presence. "Kamiranzowu" swamp, translating to something like "where elephants cannot cross", was one of our first stops on the tour.
The entrance to the Kamiranzovu Trail and the swamp itself
But lets start at the beginning. After touching down in Kigali, Fabio Pupin, Dominik Hügli and I set off to set up camp in the largest forest in Rwanda, Nyungwe, on the western edge of the country, bordering the Democratic Republic of the Congo. The aim of the trip was to catalogue the amphibian diversity harbored here, and to investigate, using genetic methods, how it is related to other East African hot spots. As chytrid fungus, a major cause of global amphibian decline is a pressing issue in amphibian conservation, we also swabbed frogs to send to colleagues in the UK for screening.
Swabbing frogs for chytrid. Home, sweet home! one of the camps while out in the field. We would usually stay two or three nights at the same spot before moving on
To try to cover more than one type of habitat, we set up camps near the edges of the Kamiranovu swamp, near the summit of Mt. Bigugu (almost 3000a.s.l.) and in the exclave forest of Cyamudongo. We were extremely well taken care of, by some of the best cooking around (well... given the menu consisted pretty much entirely out of rice and beans). Jeremy, our cook, traveled with us the whole way and astonished us over and over by cooking amazing stews from basically nothing and being able to pick a pot up out of the fire that has been sitting there for a good hour, with his bare hands!
Jeremy, our cook. Fabio and Dominik getting passport photos taken to extend their visas
Unfortunately some difficulties with permits, visas and some unusually dry weather meant that we could not quite visit as many sites as we would have liked. Nonetheless, we found one of the largest species of reed frog I have ever encountered called Hyperolius discodactylus, a species which has complicated taxonomic history, that, because of our field work, we could provide some clarity on.
A Hyperolius discodactylus female. These frogs are almost 4cm in length (that's big for a reed frog). Reed frogs often have translucent skin and this particular female has a belly full of large, white eggs, which she will lay as a sticky mass on plants overhanging streams. Here they are safe from many aquatic predators and when the tadpoles are ready to hatch, they will drop into the water below!
The Hunt for the Egg Frogs
..yes.. egg frogs. Not the most appealing name (apparently named after their oval-shaped bodies), but they are fantastic little creatures. Distributed across Central and parts of West Africa, some 15 species make up the genus Leptodactylodon. Although they are usually fairly inconspicuous, earth-toned frogs, turn them over and you will find brilliant spots and sometimes even bizarre ossifications in males that stick out of their chest.
Dull, leaf-litter colours ontop, bright blue spots below. There is more to egg frogs than meets the eye.
As it turns out, they are also incredibly hard to find, or rather, get to. Once you find a neat little stream in the forest, you might be lucky enough to hear one calling, but as we had to learn the hard way, they usually sit comfortable hidden under huge rocks, impossible to get to. Easier to find where their tadpoles, which inhabit thin films of water running over rocks, or little depressions in shallow sandy streams, and have the most peculiar mouth parts.
But I am getting ahead of myself again. So Michael Barej, from the Natural History Musem, Nono Gonwouo from the CAMHERP Conservatin Foundation in Yaounde and I were on a quest to try and collect as many of these egg frogs as possible, to try to better understand how they are related to each other. This was an important chapter of Michael's PhD thesis, and might help understand the biogeographic history of the region (why animals are where they are and not else where). I had my own side goals, to find some of the more peculiar toads of Africa, the miniature Wolterstorffina toads...
So with the truck loaded, we departed from the Cameroonian capital, Yaounde. We wanted to hit 5 sites that we knew were know localities for different species of egg frogs and they took us close to Mt. Cameroon, Mt. Nlonako, Mt. Bamboutu, Fotabong and finally south all the way to Kribi, before returning to Younde, with a final stop just outside the city, on Mt. Kala.
It was certainly one of the more adventurous trips I have been on, which made for some unforgettable moments. As is customary, when we arrived at a new place, we first stopped by the house of the chief to asked for permission to work in the surrounding forests. As we arrived in Fotabong, we asked for directions, to what turned out to be the Chief's wive. We gave her a lift and in return she would guide us up the windy roads to their house, when CRASH, we slid off the road and the truck came to a crashing halt as we hit a tree that luckily stopped us from tumbling down further. No one was hurt, it was late and getting dark, so we decided to push on on foot. Tomorrow would be a better day. The following morning, it didn't take long to find enough people to help us get our truck back on the road and sure enough, we became the talk of the town; how could we be so foolish to try to take a car up that footpath!! if only there was someone in the car with us that knew better ;) The truck had to endure a few dents and scratches, but we were back on the "road" in no time!
Our pick-up truck on its side. Michael taking a well deserved break in the early hours in Fotabong.
Most of the month in the field, we were pitching tents and living off what we could fit in the back of the truck. Breakfast was usually fresh fruit (bananas, avocados, tomatoes), onions and depending on whether we were in the former French or British territories, baguette or sliced white bread.
The trip was hugely successful and we managed to find over 100 species of reptiles and amphibians, including some absolutely incredible creatures like the hairy frog or the rhinoceros viper. Not to mention some absolutely breath taking views, like from the top of Mt. Bambutou. Take a look at some of the stunning animals we encountered.
The Golden Squeaker of Mt. Mulanje
Biogeographically, Malawi is interesting. We know a lot about East Africa and Southern Africa, but Malawi somehow falls in the middle, and no one is really sure whether the animals in its forests are close relatives to East African animals or Southern African animals. There is the Nyika Plateau in the north that somehow feels like it could be an extension of the Tanzanian Eastern Arc Mountain rifting, and then there is the peculiar Mulanje Massive in the south, that, rising like Inselbergs, seem to have more in common with Mozambican highlands, but do the animals that live there tell the same tale?
Together with colleagues from the UK and Germany and teaming up with biologists from the museum in Blantyre, our target was to climb Mount Mulanje and collect some of the amphibians that inhabit it, hoping the secretes in their DNA could tell us more about the history of the region.
Mt. Mulanje lurking in the background, and near the top:
After establishing Base Camp in the town of Mulanje and gathering supplies, we decided to tackle the mountain from the south, through the Ruo Gorge. Here, a trail leads up along a water way to a small hydroelectric dam perhaps 2/3rds of the way up. This was going to be our camp site for a few days. The trail was surrounded by lush forest, but now and again there would be completely dry riverbeds cutting down the mountain side. This should have been a warning sign, but with so little rain that had been falling the month before, rain that we desperately needed to find active amphibians, flash floods never crossed our minds. As we neared our prospective camp site, a small clearing upstream of the dam, lo and behold, it started rain. By the buckets! Excited to get set up and desperate to keep our equipment dry, we pitched our tents a little too close to the water's edge, thinking the meter or two clearance we had from the water level would be more than enough. As night fell and we were finishing up dinner, we suddenly realized we didn't have to go down to the stream to wash our plates, the stream had come to us! The water level was climbing fast and had already reached the first tent. After relocating further up hill, we contemplated about how a somewhat comical situation could have been life threatening had we already been asleep in the tents.
Campsite 2.0. After relocating away from the range of the flooding zone of the river.
All is well that ends well and we managed to descend Mt. Mulanje a few nights later, having found some unusual animals, such as a squeaker frog (so named after their high-pitched mating calls), no more than 2 or 3 cm in length, but with a lovely golden tinge, that is most likely completely new to science.
Investigating little tributaries for tadpoles (left) and the mysterious, golden squeaker frog (right)