The cry of the jungle
15 October 2008
Bruna Bezerra, a Brazilian student studying for her PhD in the Department of Biological Sciences, has just returned from the rain forest where she was conducting research on the vocal communication of the rare monkey, the golden-backed uacari.
Bezerra has been undertaking expeditions to the Amazon since 2006. Her base is the Jaú National Park, in Amazonia, Brazil, the second largest national park in Latin America. Just getting to her field area is a challenge. From the nearest city, Manaus, she travels by boat along the Rio Negro for about 24 hours, taking everything with her that she is likely to need for the next few weeks. She usually travels alone, although her supervisor and colleagues visit for a few days during some trips. When in the field, Bezerra stays with a local family who live in a small wooden hut (left) without electricity, sleeping in a hammock and taking cold showers in the river. A communal hole-in-the-ground acts as a toilet. She relates some amusing tales about her ablutions:
“One day I was showering in the river when I saw the head of a cayman (alligator) coming towards me. It looked soooo scary! Once safely out of the water I discovered it was literally just its head; the locals had eaten the rest of it and then thrown the head back into the river. It was coming towards me because there were some piranhas nibbling on it, pushing the head forwards.” Another time she found a wild piglet that had fallen into the toilet hole which had to be rescued at four in the morning before she could use the facilites.
About ten per cent of the Jaú National Park is swampland and it is here that these rare, shy, arboreal monkeys can be found
About ten per cent of the Jaú National Park is Igapó forest – blackwater swampland that is one of the most difficult and challenging of South America’s habitats – and it is here that these rare, shy, arboreal monkeys can be found. When flooded, there is far more fruit available in the Igapó forest, which is probably why the uacari, having a preference for hard, unripe seeds, visit during the wet season. Thus Bezerra’s studies have to be conducted entirely from a small wooden canoe which she and a local guide use to gingerly move around the flooded jungle, avoiding the caymans, piranhas, snakes, scorpions, spiders and other creepy crawlies, while enjoying the antics of creatures like giant otters, and swimming with tame dolphins, now living wild in the Negro River.
The golden-backed uacari, Cacajao ouakary, has an unusually short tail, characteristic of primates of the Cacajao genus, a reddish-brown body and thighs, with black head, arms, chest and legs, but a bright golden mid-back. It lives in social groups of up to 200 individuals and mating seems to occur throughout the wet season. Adult females nurse and care for their babies until they are around a year old. Only a few preliminary investigations of diet and habitat choice have so far been conducted on them and so Bezerra’s project will provide completely new data about the behav-ioural and social ecology of this rare primate, as well as helping to understand the social status of individuals and groups, which will then be used for future conservation and welfare plans.
Vocalisations are an essential commun-ication tool for primates that live in trees, because of the visual restrictions imposed by their habitat. Despite this, studies of vocal repertoires have only been conducted on 42 of the approx-imately 625 primate species described so far, of which nearly 25 per cent are at risk of extinction. The golden-backed uacari used to be classified as ‘vulnerable’, although that has recently been changed to ‘low risk’. However, knowing the locals hunt the golden-backed uacari for food, Bezerra believes the numbers have been overestimated.
The type of call heard gives an idea of the uacari's emotional state and the behaviour it might be exhibiting, even if you cannot see it
Capturing the uacari’s vocalisations and their contexts can become an important instrument with which to survey the species, which is one of the first steps in a conservation plan. For example, if you hear an animal vocalising in the wild, you know that it is actually there. Furthermore, the type of call heard gives an idea of the uacari’s emotional state and the behaviour it might be exhibiting, even if you cannot see it. Knowledge of vocal behaviours and repertoires is also valuable for solving taxonomic issues, as different species have different vocal signals. So understanding vocal behaviour and repertoire can became an extra tool to help taxonomists to differentiate between species. Finally, data on the behaviour and the sociality of a species in the wild can help zoos and laboratories make improvements in their enclosures, so that captive animals behave more like they would in the wild.
Bezerra has just returned from the Amazon after spending the past six months studying the monkeys in their natural habitat, so she still has a lot of data to compile and analyse before a fuller picture of how to conserve these elusive animals starts to emerge. “At times I feel like a cross between a Victorian explorer and David Attenborough,” she says, but apart from the risk of getting malaria or rabies, being drowned when the canoe suddenly fills with water in a torrential downpour, or being tipped out of the boat by caymans gliding beneath it, it’s a pretty interesting life.
Bruna Bezerra / Biological Sciences