The Red Uakari Monkey Project – End of Year Report
22nd May 2006
Introduction & Project History
Uakaris (Cacajao) are the largest members of the subfamily Pitheciinae and are one of the least-known Neotropical primate genera. There are two Uakari species; C. melanocephalus, which has two subspecies (melanocephalus and ouakary) and C. calvus, which has four subspecies (calvus, rubicundus, novaesi and ucayalii) (Hershkovitz 1987). Of these, only C c. calvus has been studied in any detail (Ayres 1986). All species are specialist feeders on hard-shelled fruit, range over large areas of varied forest habitats within the Amazon basin, and form large groups which often fission into smaller groups (Ayres, 1986; Barnett & Brandon-Jones, 1997). Uakaris are listed as Indeterminate/Vulnerable by the IUCN (Red List 1994) and are in Appendix I of CITES.Red uakaris appear to have been exterminated from much of their range (Aquino, 1988), and are threatened by hunting, logging and habitat disturbance. The importance of key plant species and habitat types, which are highlighted by this project, should be considered when planning for the management of the remaining populations.
A year-round ecological study on red uakaris (subspecies rubicundus, novaesi and ucayalii) has never been completed, because attempts to establish a site at which sufficient observations are possible, have consistently failed. The species has a patchy distribution, and combined with very large range sizes this has made data collection difficult. This project has established an area where several large groups of uakaris are habituated and we have collected 945 hours good ecological data during the first two years of the project. This data at last gives us knowledge on red uakari ecology, on which we base our conservation strategies.
Much of the Yavari river basin is designated as logging concession, and one of the key aims of the project was to predict how the selective logging in these areas would impact on the populations of this endangered primate. In addition to ecological data on the monkeys, we surveyed tree composition in terra firme, aguajal and varzea forests and estimated the volume of standing timber for hardwoods and softwoods timber species. Using the values of timber in sawmills on the lower Yavari, and looking at current logging practices on the Yavari, we made attempts to predict which species would be removed from logging concessions. We examined the overlap in uakari diet with timber species to make predictions on how logging in the Yavari might affect populations of this primate. One of the most striking findings of the first two years of research was the red uakaris’ dependence on the ripe pulp of the aguaje palm fruit (Mauritia flexuosa). This palm fruit is also harvested in large numbers by people, to be made into sweet drinks and ice-cream, or eaten raw. Aguaje fruit bunches are generally collected by felling the palm, reducing next years harvest for animals and people alike. In certain parts of the red uakaris range the removal of this non-timber resource will have a more serious impact on uakari populations than logging. A paper discussing these findings is currently in preparation.
The Red Uakari Monkey Project began with a Rufford small grant of £4990 in 2003 awarded to Mark Bowler of the Durrell Institute of Conservation and Ecology (DICE). Following two years of ecological research, several scientific papers are in preparation (see below), but one of the greatest achievements during the first two years of the project was that the study area, and 10,000 hectares surrounding it, was awarded to DICE and WCS-Peru to manage as a conservation concession; “Lago Preto Conservation Concession”. This was a result of a long process lead by WCS-Peru and DICE. The main purpose of the concession is to protect the unique density of red uakari monkeys, and the presence of our research project, and the work we are doing proved instrumental in the success of the proposals. Our research continues to be used in technical proposals for the management of the concession, and it is important that we continue to work with DICE and WCS-Peru providing information for these plans and official documents for the Peruvian authorities.
Research conducted in the area by DICE and WCS demonstrated that the continuous presence of our project researchers in the area also had positive effects on other species. Fish surveys showed that the closest lake to the study area (Lago Preto itself) contained by far the highest populations of the huge, endangered and highly sought after food-fish ‘Paiche’ (Arapaima gigas). There were also high densities of ‘Arowanna’ (Osteoglossum bicirrosum), a fish often threatened by over fishing for the ornamental fish trade. These differences are, without doubt, due to the protection given simply by our presence at the site. In addition spider monkeys, rarely seen in the area, started to be observed more often towards the end of the two years, and casual observations of giant otters and some game bird species appeared much more frequent in the second year than the first.
Following the success of WCS-Peru and DICE in securing the conservation concession, a continuation grant was sought to work with the DICE & WCS team to gather the information necessary to manage the uakari monkey population within the concession area. A Rufford Continuation Grant of £2483 was awarded on May 17th 2005 (ref. 120.01.05).
Objectives
- To erect signs and mark the boundaries of the Lago Preto Conservation Concession.
- To locate additional uakari monkey groups within the new conservation concession and to find out which areas might be important for the species.
- To estimate the number of uakari groups within the conservation concession.
- To record the age structure of other groups for further evidence for the seasonality of births.
- To observe the logging and hunting activities of logging concession holders near to the conservation concession.
- To train and co-ordinate with Peruvian staff, including those of WCS-Peru in data collection to monitor the uakari populations at Lago Preto.
The study area
The 10,000ha Lago Preto Conservation Concession is on the Peruvian side of the Yavari River, Southeast of Iquitos, close to the mouth of the Yavarí Mirim river (427’S, 7145’W). The area has three distinct habitat types: ‘aguajal’ palm swamp forest, seasonally flooded riparian white-water forests commonly referred to as ‘varzea’and higher ‘terra firme’ forests, consisting, in part, of old alluvial terraces with clay soils, poor in nutrients. Average rainfall is around 240.7mm per year varying from 157.2mm in July to 307.8mm in April (data from Jenaro Herrera, Marengo 1983). Water levels generally peak around April, when the varzea, sometimes including the higher restingas (levees or areas of higher ground in the varzea forest), are completely inundated. The length of the high water season, when the varzea is flooded, can vary greatly depending on rainfall locally and in the Andes. Generally it starts between December and February and lasts until around June.
The behavioural and ecological data collected by Mark Bowler during the first two years of the project were collected at a study site of around 1500ha close to LakePreto itself within the Lago Preto Conservation Concession. There are over 40km of trails through the three habitats at this study site.
Methods
Using the Rufford Continuation Grant awarded in May 2005, principal researcher Mark Bowler joined two extended joint expeditions up the Yavari with Dr. Richard Bodmer and biologists from DICE and WCS. The expeditions were run from research boats ‘Lobo del Rio’ and ‘Nutria’ run by DICE, WCS-Peru and AmazonEco. One expedition was made in June and July 2005 during the low water season, and one in April 2006 at the peak of the high water season.
June and July 2005
During June and July the research boats were moored downriver from the study site at LakePreto close to LakeIpiranga. Trails were cut here to create a new study area joined to the trail system at LakePreto. This area has large areas of seasonally flooded varzea forest and is separated from the Preto site by a large area of Aguajal palm swamp forest.
Census data on all primates was taken by DICE and WCS-Peru researchers on new trails at the LakeIpiranga study area. Uakari densities will be estimated using this data along with data taken at the Lago Preto Study area.
Ecological data was taken on the uakari groups at both study sites. Mark Bowler and Chris Barton from DICE located groups of uakari each day by walking the trail systems, with each researcher working on a different trail system. We followed the groups until they settled into their sleeping trees at dusk or the group was lost, returning to find the group at dawn the next day. We used point scan sampling, collecting data at ten-minute intervals (Altmann 1974). Allowing one minute to complete the scans, we recorded location, group size, habitat, and the behaviour of each visible individual. We recorded feeding as the behaviour when an animal was ingesting or processing food, including reaching, masticating, swallowing or carrying food items. Where possible we recorded the species, plant parts (seeds, pulp, arils, flowers, leaves or otherwise) and the maturity of the fruit eaten by the individual. For all new tree species consumed we tagged the first two or more examples and recorded the location so that the tree could be identified by a botanist at a later date. We photographed and preserved fruits and leaves for identification later.
Uakari groups at Lago Preto are habituated to varying degrees. In many cases the monkeys tolerated our presence at ranges of 20-30m, but would flee or mob us at closer range. We could not generally observe the monkeys from directly below the group, without disturbing them, unless the canopy was thick enough to obscure us. This often meant that we were not close enough, or did not have a clear enough view, to identify food items eaten by individuals during instantaneous scan sampling. For these reasons one-zero sampling (Altmann 1974) was employed in addition to the scan sampling methods in which a ‘1’ was recorded for each food item if it was seen used during a ten-minute period. The one-zero data probably underestimates the importance of certain species that had crowns full of fruit that were fed on intensively by large uakari groups.
April 2006
Census data on all primates was taken on trails at the Lago Preto Study area. Uakari densities will be estimated using this data. When uakaris were encountered, researchers attempted to record the age-sex composition of the group, paying particular attention to females with dependent and independent young. Numbers of young were recorded along with their sizes (as a percentage of the size of the mother), the position in which they were being carried and the colour of their faces. All of these help to give an idea of the age of the young. This data, in the long term, will help us gain an idea of the recruitment into the population at Lago Preto and of the seasonality of births. Things we were not able to look at with just two years data.
Mark Bowler coordinated with, and gave instruction in methodology to, Jorge Flores and Pedro Perez of WCS-Peru. They will continue to monitor the uakari populations at Lago Preto between May and June. In May, training was also given in the UK to research assistant Shona McCann-Woodfrom DICE who will be collecting ecological data of red uakaris for the project during June and July. Special attention will be given to the age-sex composition of the groups.
Discussions with people from the communities of Esperanza and Carolina were conducted by WCS staff in order to learn more about the logging activities in the area.
Results and Discussion
June and July 2005
Signs were erected on the boundaries of the concession, and at the entrances to the main lakes. At the Lago Preto research site, a large sign and map showing the area of the Lago Preto Conservation Concession was erected.
Signs on the concession boundary
Uniquely, our census data shows that the Red Uakari Monkey Cacajao calvus ucayalii is the most abundant primate in the Lago Preto Conservation Concession (308.97 ind./100km). The next most abundant of the 13 species found in the reserve are; common squirrel monkeySaimirí sciureus (226.90 ind./100km), saddleback tamarinSaguinus fuscicollis (38.62 ind./100km), monk saki monkeyPithecia monachus (27.59 ind./100km), woolly monkeyLagothrix lagothricha (24.83 ind./100km) and brown capuchinCebus apella (20.69 ind./100km).
Just over one half the area of the concession was searched over the duration of the expedition, and several new uakari groups were located with a total of around 75 individuals. During this time period 160 to 200 uakari monkeys were also using the area of the original study site, and these are thought to be the original groups studied. Using these figures, and taking the distribution of habitat into account, we estimated conservatively that about 350 red uakari monkeys might be using the conservation concession area in June and July 2005.
The age structure in the groups observed provided further evidence that births occur mainly between August and November. Few young that would have been born between August and November 2004 were observed.
The North-eastern corner of the conservation concession is close to a logging concession and timber is floated out on a stream that runs through the conservation concession. The timbermen are entitled to pass through the conservation concession, but must not extract timber from it or hunt there. We discovered a small logging camp inside the conservation concession, in which we found evidence of hunting, including red uakari monkey fur. The camp was not in use, but had been used when the water levels were high enough to float out timber. We also discovered that timber trees had been felled within the Lago Preto Conservation Concession. Peruvian biologists from WCS-Peru will negotiate with the logging concession owners to try to ensure that they do not hunt or extract timber from the conservation concession, and that they do not make further camps within the reserve boundaries.
Logging camp with the conservation concession
April 2006
At least two separate uakari groups were encountered during the census on separate occasions. On no occasion was an accurate count possible, but one group contained a minimum of 70 individuals and the other a minimum of 30 individuals. It is possible that these two groups represented the whole population of 150 plus individuals because the groups often spread over a large area and are difficult to count. Upper estimates of groups encountered simultaneously would suggest that this is the case.
Our observations suggested that a very high proportion of the females in the larger of the two groups had young between the ages of about 6 to 9 months. Many of these young were travelling indepentenly except to cross large gaps, or when researchers were spotted by the monkeys. A minimum count of 5 babies being carried by their mothers was made, but the actual number would have been larger given that a large proportion of females observed were with young. The age of these young, combined with data from the first two years of the project support the observation that births are seasonal (though one relatively new-born baby was observed in April 2004). The number of young observed is even more interesting. Between August and November 2003 several new-born babies were observed, whereas between August and November 2004 only one new-born uakari was observed during many hour of observation of the groups at the Lago Preto study site. The sighting of several babies that would have been born between August and November 2005 in relatively few hours of observation is therefore very interesting. 2004 was a year of extremely low rainfall in the Amazon, and it is possible this is why few births occurred.
Discussions with people from the communities of Esperanza and Carolina revealed that one of the logging companies in the area was starting to extract ‘cumala’ timber (Myristicaceae) on the Yavari and YavariMiriRivers. We had previously believed that logging operations were removing almost exclusively hardwood species described by the common name ‘cedro’ (Cedrela spp.) and possibly ‘tornillo’ (Cedrelinga spp). If only these species were harvested, our survey conducted in 2004 suggests that around one tree every seven hectares would be extracted, with relatively little impact on the red uakaris. If softwood trees like cumala of diameter >40cm were also harvested 1.4 trees/ha would be extracted, with much greater impact on the red uakaris. Our research from 2003 to 2005 has shown that red uakaris eat many species of Myristicaceae, and the effects of removing this timber should be considered. This new information about the logging activities will have an important bearing on our conservation strategy in the area and changes the conclusions we make in the paper were are currently preparing on the potential effects of logging and resource extraction on red uakari monkeys.