Zoologists find conservation goldmine in Guyana
Scientists grappling with an anaconda
18 June 2010 by Rob Pickles
Rob Pickles travelled to a remote stretch of rainforest in search of the rare giant otter. He found it, along with a variety of other animals beyond his wildest hopes.
Giant anacondas are not the sort of beasts to suffer fools gladly. Anything that can turn you into a loose, wet bag of shattered bone deserves to be treated with a great deal of respect, which was why we approached this particular polished black coil of muscle and sinew with some trepidation.
"That is a BIG camoodie Boy!" Kevin grinned broadly. Ash sized up the snake with a professional eye and thought it looked catchable. "Let's just hope she doesn't musk; if she musks we'll stink of anaconda for weeks. Ryol, you're tailman." Ryol grumbled something about always being tailman and perpetually covered in musk and having only just washed his clothes to top it all, but resigned himself to his role.
Anything which can turn you into a loose, wet bag of shattered bone deserves to be treated with a great deal of respect.
The anaconda reacted to the weight of four grown men on her with some displeasure and writhed with shocking strength. Ryol hauled on her tail for all he was worth and Niall clamped tight behind the head as her mouth opened with a husky hiss that smelt of rotten meat and exposed rows of sharp teeth. The jaws were bound, eyes covered, and bit by bit the fight left her. We had a length of rope in the boat and measured her from nose to tail, coming out with a final length of just over 5·5m with a girth of nearly 70cm.
It was a huge snake, a leviathan from another age, but where we were this wasn't an aberration; we'd already seen five others of similar proportions. We were on the Rewa Head in Guyana's interior, right in the heart of the Guiana Shield, a huge, ancient dome of rock. The Shield spans Venezuela, the Guianas and part of northern Brazil, and on its back lies the largest single tract of rainforest anywhere in the world, with scores of endemic species found nowhere else. The Rewa river itself is a devil to navigate, cut midway along its length by a string of cataracts and falls requiring heavy portage work to reach its headwaters.
The giant otter
What initially brought us to the middle of Guyana was the species on which my PhD was based, the giant otter. A bold, gregarious, sinuous creature longer than a man is tall. The giant otter was decimated by the pelt hunting of the last century, and although populations have begun to recover it is still classified as endangered. What we didn't know was how genetically differentiated populations were, or where migration occurred, if at all. I was interested to see whether any migration was occurring among the Guyanese otters and those of the Orinoco and Amazonian Peru. To find out I needed otter DNA, and to get that I had to find the packs, locate their latrines and scoop up their steaming fresh spraint.
It was the Rewa Head's uncompromising nature, over which we sweated buckets with the portaging, which had prevented the hunters from navigating to the headwaters. And it was up here that an enclave of giant otters survived the population crash, and where I'd been told you could witness wildlife flourishing in an almost pre-Columbus state. After hearing those tales, I proposed a trip with good friend and fellow biologist Niall McCann. We realised that basic survey work was urgently needed in the region, and were lucky enough to be put in touch with a man who knew the interior and its wildlife like the back of his hand. Ashley Holland had been working out there for years and he and his team - Ryol, Nando and Kevin - knew the ways of the rivers and the portage lines, were adept at catching caiman and anacondas, and could also weave a mighty fine basket.
We timed our trip to coincide with the dry season, but that year the weather gods hadn't been appeased and it rained, heavily and frequently. The river came up, hammock posts squelched and came down and the kitchen was almost washed away. Both Kevin and Ash were nailed by 'mosquito worm' and had to pepper themselves with patches of gaffer tape to suffocate the burrowing maggots. It's fair to say conditions were not ideal, but during our brief 22-day spell in the Rewa Head we had encounters with wildlife that tropical biologists can spend years in the field waiting for.
A dwarf caiman
There is no human disturbance at the Rewa Head, but people did once come here - the area is not 'pristine' in the sense that it has never seen Man's hand. Balata bleeders made the arduous journey up here in the 1970s to tap latex from the rubber trees, and in the forest the rotting remains of a compressor and pipes are all that survive from an abandoned gold-dredging venture. But the falls are a barrier to all but the bravest, and now the only people to go above Corona Falls are Ash and the odd intrepid twitcher.
As there is no human hunting pressure, game species like tapir, paca and curassow are abundant and unafraid of humans. And with the abundant game comes a healthy predator population. In our camera traps we regularly recorded four species of big cat including puma, while on the river we glimpsed jaguar three times during the expedition. We saw several tapirs bearing rake-marks on their flanks that told of narrow escapes from jaguar or puma attacks, and at the entrance to a paca den we saw the footprints of the enigmatic bush dog.
Crucially, we also found five packs of giant otters and managed to collect the samples I needed. What I found in the genetics was that far from being isolated, the giant otters seemed to use seasonal breakdowns between drainage basins, when floodplains become blurred together, to hop from one tributary to another. The Orinoco, it seems, is a sort of melting pot between the otter populations of Guyana and northern Peru. Identifying where these routes of migration occur is now the next challenge, to ensure we direct conservation effort at the right spots to keep the populations in contact with each other.
Otters and tapirs and snakes, oh my!
So why is the Rewa Head so special? Firstly, it has high diversity of species, including threatened and charismatic rainforest animals. Over the expedition we recorded the presence of 33 medium-to-large mammal species, and the total bird count for the area reached 251 from mist nets, camera traps and drift surveys. These included beauties such as the spangled cotinga, crimson topaz, and purple-throated fruitcrow, ten species endemic to the Guianan Shield, and 16 species of raptor, including the awesome and threatened harpy and crested eagles.
The list of 'giants' and 'largest' species found in the Rewa Head also makes impressive reading: along with the giant otter, largest snake (anaconda) and largest eagle (harpy), we found the goliath bird-eating spider, giant anteater and giant armadillo. More importantly, 14 of the species recorded are listed as globally threatened, yet here several seem to be abundant. We encountered tapirs several times during the drift surveys, and they were the second most common species in the camera traps.
An ocelot captured by night vision
Secondly, the area's situation is exceptional. The falls have given the Rewa Head a degree of natural protection from encroachment that has preserved the area so far. It also sits plum between Conservation International's Upper Essequibo Concession and the proposed Kanuku Mountains Protected Area, forming a natural link between the two areas and together spanning most of the width of southern Guyana.
Thirdly, and most importantly, the region's valuable natural resources mean it is by no means certain the Rewa Head will remain in its present unsullied state. Gold, oil and timber are all found there, and the Rewa Head itself lies within a logging concession, with felling earmarked to begin within the next few years.
We've just entered the 'Year of Biodiversity', and although Copenhagen didn't deliver what was hoped, there is a realisation that attitudes must change, and policy with it, to make it economically worthwhile for poor countries to preserve their natural heritage rather than exploit it. Guyana is the poorest country in South America, so it is under enormous pressure to use its natural resources for economic growth.
Thankfully President Jagdeo has realised that Guyana's forests should be worth more standing than felled, and has offered them up as a global carbon sink. Guyana possesses some of the most carbon-rich forests in South America which, coupled with the high species diversity and the number of plants and animals found only in the Guianan Shield, make these forests an extremely valuable resource - not just to a few conservationists, but to the international community and the Guyanan nation.
There are signs the message is getting through. Last year Norway boldly pledged $250 million to help preserve Guyana's forests through the UN's Reducing Emissions from Deforestation & Degradation (REDD) initiative. It is hoped that other nations will follow Norway's lead and help make Guyana a model of how global carbon offsetting can prevent the remorseless creep of dredgers, drillers and chainsaws.
We are just starting to scratch the surface of the species richness of the Rupununi Basin, of which the Rewa is a tributary. Currently the region's tally of vertebrate species stands at over 1,400, with very little research yet conducted on the fish, reptile and amphibian communities. With further exploration this figure is certain to rise, and this small corner of the Guianan Shield, comprising lowland rainforest, savannah and a unique Caribbean-draining river basin, looks likely to be one of the most species-rich regions in the world. Conservation organisations have recently begun looking in earnest and it seems that the spotlight has, all of a sudden, fallen on Guyana.
Rob Pickles is a PhD student at the Institute of Zoology and the University of Kent, studying the population genetics of the giant otter.