14 June 2015: Bwindi Impenetrable National Park
For those of you who are new to this blog, please see entries from my previous field season in 2013 for a detailed explanation of the main goals of this work, but in summary, I am a herpetologist working under the auspices of a grant from the US National Science Foundation (Grant No. DEB-1145459) to understand the herpetological biodiversity of forests in the Congo Basin. Please note that posts will be granted from my students and colleagues, but not the general public. Apologies for Latin names not being in italics- for some reason it didn't transfer from my Word file and internet time is too limited to fix it all up here. Thanks!
Now that the team, consisting of myself, expedition medic Wendy Rivera Greenbaum (R.N., B.S.N), Ph.D. student Daniel Hughes and Ugandan herpetologist Mathias Behangana, has finished three days of fieldwork, it is time to take stock of our progress. Thus far, we haven’t found any amphibians or reptiles that I’ve failed to find in the past, but we have found a few things that are rather rare, including some additional specimens of species that my lab has already confirmed to be new to science, based on DNA samples collected in previous years here in Uganda and neighboring DR Congo. However, the chance encounters with other wildlife have been spectacular, as I will explain below.
The first place I wanted to go was Kyambura (pronounced Chee-ambura) Gorge, in the southeastern corner of Queen Elizabeth National Park, because it is home to a unique habitat with its own endemic species of snake. Most of the park is a mixture of African savanna and woodland, including acacia (note the official scientific genus name for African acacia trees was recently changed to either Vachellia or Senegalia depending on the specific species, sensu Miller et al., 2014) and fig trees. Although thorny shrubs obscure one’s view here and there, most of the landscape is very open and one can see for miles in every direction, and we were able to spot an elephant or two in the distance as we entered the park on the road from the capital of Kampala. In stark contrast to the yellowish-brown color of the savannas, Kyambura Gorge is full of verdant gallery forest, which can grow because of the Kyambura River, which passes through the gorge on its way to Africa’s great lakes system—the combination of the river’s moisture and a 300-meter fissure that traps the humidity allows the rich vegetation to thrive in this one small area of the park. I wondered if the forest was one of the tiny remnants of the once widespread lowland rainforest from the Congo Basin (in DR Congo and Congo Brazzaville) that survives in Uganda and western Kenya (climate change during the Miocene to the present caused most of the previously widespread forest to retract, leaving tiny pockets called refugia behind in a few places in East Africa), and whether the herpetofauna of these currently separated forests would be genetically identical as I had found before. A photo of the gorge is below.
Back in the late 1990s, a biodiversity survey of the gorge turned up a single specimen of a viper in the genus Atheris, which are commonly known as the bush vipers. Like all vipers, Atheris are sit-and-wait ambush predators, usually of warm-blooded prey such as rodents and even birds, and they can be found in bushes and trees waiting for unsuspecting prey at night, and in the early hours of the morning when they may bask for a few minutes to warm their chilly bodies. Although some serious bites have been reported and severe tissue damage has occurred, most Atheris bites are rare and not fatal. The year after its discovery, the single specimen from Kyambura was sent to the eminent African herpetologist Donald Broadley, who described it as a new species, Atheris acuminata. Based on the staggered, broken-shingle appearance of its yellowish-green scales, it was clear that the new species was the close cousin to Atheris hispida, a similar looking species described from DR Congo during the colonial era in the 1950s. The two species were distinguished by minute differences in scale counts and color pattern. But since the single specimen of A. acuminata was found 17 years ago, no additional individuals turned up, perhaps because no herpetologist worked at the gorge during the interim. Because a recent study has made DNA data available from most Atheris species (Menegon et al., 2014), including A. hispida, I wondered whether A. acuminata would hold up as a valid species if a fresh sample could be obtained to compare it to its close cousin. After all, the scale pattern differences seemed to be relatively minor, and looking at the map that Broadley (1998) published in the description, the range of A. hispida seems to surround A. acuminata. Could the latter species actually be a slight variant of the former one? I was dying to find out, but I knew it would be a shot in the dark to find the snake, because they are generally rare and we would have to be extraordinarily lucky to find one.
After picking up a ranger named Bernard to guide us into the gorge and protect us from any lions or leopard that happened to wander too close, we managed to capture a blue-headed tree lizard (Acanthocercus kiwuensis [unpublished DNA results suggests it is a valid species]) on a tree near the edge of the forest. We then hiked down the precipitous trail into the gorge, crossed a swaying wooden bridge over the Kyambura River, and started searching for the snake. It was a hot day and the combination of high temperatures, high humidity and strenuous exercise caused me to be drenched in sweat after a couple hours of searching. We managed to find a couple rocket frogs (genus Ptychadena) that were hopping through the vegetation adjacent to the swiftly flowing brown water, and at one point we even spotted a harmless green snake (Hapsidophrys smaragdina) on a tree that was overhanging the river (this species is only found in rainforest), but it was just out of reach on a flimsy limb, and perhaps sensing herpetologists nearby, it quickly ascended the spindly branches until it disappeared from sight several meters above us. Not wanting to walk away nearly empty handed, I decided to collect a wicked-looking red centipede with curious wing-like structures on its tail that turned up under some fallen tree bark.
After a couple more hours of fruitless searching, we decided to call it quits, but on our way back Danny spotted a large chimpanzee in a tree at least 10 meters above us. There are about 25 chimpanzees that live in the forested haven of the gorge, and Bernard recognized him as Brutus, the alpha-male leader of one of the largest family units in the area. He said it was unusual for him to be alone, because we couldn’t see or hear any other chimps nearby, and he wondered whether Brutus had finally become so old that a younger rival pushed him out of his leadership position to live a life of exile. Delighted to have seen a chimpanzee in the wild, a first for Wendy, Danny and I, we took a few photos (one is below) and moved on.
After replenishing our energy with a goat stew, we returned to the gorge just after dusk to see if our luck would improve. Our hopes surged when a light rain started to fall when we reached the heart of the forest, because moisture can often prompt reptiles and amphibians to emerge from their hiding places deep underground, but hours more searching turned up nearly nothing, except for a small green frog that was spotted by Wendy and a small skink by Mathias, both of which made their escape into the thick underbrush before we could get a good look at them. However, we were surprised to see other warm-blooded inhabitants of the forest, including several species of birds that were resting on branches a couple meters above the ground. Brilliant Pygmy Kingfishers, a handsome orangish bird with a long tail—the Paradise Flycatcher, and a group of four Black Bee-eaters (Mathias told us bird watchers pay a lot of money for a glimpse of the latter) turned up in the bright beams of our headlamps. And then after hearing a weird sound emanating from the river, Danny noticed a small group of hippos cavorting in the river, which in some places was less than a meter from the edge of our trail in the forest. Hippos can be very dangerous if one is traveling in a small boat in their territory, because they can easily overturn it and use their sharp tusks to kill the passenger. Bernard assured us they were far less dangerous on land, but we all had a good scare when an enormous hippo snorted loudly at us from the hidden side of some aquatic vegetation a couple meters from the river’s edge. I took some video of a couple females swimming with their babies before we had to admit defeat in our quest for Atheris acuminata. With slim pickings in general, we unanimously decided to move on to Bwindi Impenetrable National Park, where we had done a little work during the African Amphibian Working Group conference at Ruhija the year before.
Bright and early the following day, we left Kyambura and headed to Bwindi via the route through Queen Elizabeth National Park so that we could have an opportunity to see some elephants en route. Although elephants have been devastated by poaching in many areas of Africa (see lastdaysofivory.com for a short video by the Academy-award winning director of The Hurt Locker for a stark account of this), Uganda’s elephant population is actually growing because the local people are benefiting from the proceeds of ecotourism, which is booming. Key to this effort is law enforcement from the Ugandan Wildlife Authority, which is doing a great job apprehending poachers with help from the local people, who eagerly report anyone hurting their livelihood. Mathias told me that entrance fees for Queen Elizabeth, which range from $40-50 per tourist, are partly used to support local schools and medical facilities, so that the people have a vested interest in protecting the wildlife. A similar good-news story is happening in Costa Rica, which is one of the few places in the world where tropical rainforest is actually increasing, thanks again to benefits to local communities from ecotourism money. Hopefully other African countries will catch on to this win-win model of protecting the natural world with financial benefits to their people.
We hadn’t traveled far when the shout of “elephant” rang out from two of us almost simultaneously. An enormous individual was busy munching the thorny branches of an acacia tree only a few meters from the side of the road, and although he was flapping his ears to dissipate heat, he wasn’t extending them purposefully, which is a warning that he is feeling threatened and may charge. When Mathias did a quick u-turn to go back for a closer look, I asked him what happens when elephants charge a large 4X4 vehicle like the one in which we were traveling. He used the analogy of a can opener and squashed tomatoes, but he assured us he would hit the gas if the animal made any signs it would charge. Luckily, the elephant never missed a beat as it munched on the tree, and it gave us a great show while acting completely unconcerned about our presence. Because vehicles pass by the road all the time, it has probably become used to the presence of trucks with nosy tourists. Thrilled to have seen such a majestic animal so closely, we moved on.
Here and there we saw some troops of baboons, vervet monkeys and small herds of buffalo in the distance. We stopped briefly when Danny spotted an enormous black-necked spitting cobra (Naja nigricollis) that had met its demise in the road, and we were able to salvage a DNA sample from its tail to compare to a precious few additional samples that I have collected in Burundi and DR Congo over the years.
As we headed north, Mathias told us we would pass by Ishasha Sector, which is famous for a population of lions that have taken a shine to climbing fig trees to rest during the heat of the day—in almost every other part of Africa, lions will rest in the shade of trees (usually acacia trees) on the ground. Having failed to see lions in Murchison National Park on my last trip to Uganda with Danny in 2014, we decided to take a quick detour to see if we could be lucky and see them. Although Mathias has worked as an occasional tour guide operator in Uganda, Kenya and Tanzania over the years, we were surprised to hear that he hadn’t seen a lion in the wild for a decade. Like other wildlife in Africa, populations of lions have been decimated, mostly by local people trying to protect their herds of cattle and goats, and in some cases, as revenge when people are killed and eaten. Mathias told us that Queen Elizabeth has about 250 lions left, including the ones at Ishasha.
Upon entering Ishasha, we were treated to scenic views of rolling green grassy hills dotted with acacia trees. Large herds of Uganda kob, light brown deer-like animals, were everywhere, along with the chocolate-brown and black topi, buffalo, warthogs, bushbuck and waterbuck. Without warning, a hyena galloped across the road in front of us, no doubt on the way to a lion kill in the distance, because they are rarely seen during the day unless there is a carcass to be scavenged. Encouraged the lions might be in the area, we spent about an hour looking around in vain before a local ranger told us that lions had been spotted in a fig tree down the road. We followed the hot tip and sure enough, we found two lionesses sleeping on the branch of a tree (see photo below).
When we circled the tree to photograph them at ideal angles, Wendy was delighted when we discovered two cubs hidden in a hole at the base of the tree. We watched the youngsters play fight for a few minutes before heading on to Bwindi. I didn’t think the wildlife viewing could get any better, but shortly after leaving Queen Elizabeth, we were thrilled to get a glimpse of an enormous leopard (its body took up half the width of the road!) crossing the road in front of us. Very rarely seen during the day, Mathias noticed that its belly seemed to be empty, and hunger had prompted it to stalk prey during the day.
We reached the edge of Bwindi Impenetrable National Park in the late afternoon just after it started raining, and after greeting the local warden Frank Sande who remembered me from the conference at Ruhija the previous year, we were granted permission to look for frogs at the mid-elevation (ca. 1500 m) forest near the headquarters at Buhoma. We finally turned up several species of frogs, including the mystery female with her eggs shown below (photo for student cybertaxonomy project below). Hopefully the distinctive color pattern will be an easy first project for my students to identify.
As I write in the late afternoon, it is pouring rain again, discouraging our hopes to travel deep into the forest to sample a natural pond a few kilometers into the rugged terrain. With luck it will taper off and we will be able to find some species we haven’t documented from the area before. Tomorrow we plan to return to Ruhija to re-sample a swamp where we found a small number of very rare species the previous year. Stay tuned for more soon!
The following papers were cited in this post:
Broadley, D. G., 1998. A review of the genus Atheris Cope (Serpentes: Viperidae), with the description of a new species from Uganda. Herpetol. J. 8: 117–135.
Menegon, M., Loader, S.P., Marsden, S.J., Branch, W.R., Davenport, T.R.B., Ursenbacher, S., 2014. The genus Atheris (Serpentes: Viperidae) in East Africa: Phylogeny and the role of rifting and climate in shaping the current pattern of species diversity. Mol. Phylogenet. Evol. 79: 12–22.
Miller, J.T., Seigler, D., Mishler, B.D., 2014. A phylogenetic solution to the Acacia problem. Taxon 63: 653–658.