Conclusions

The results of this study clearly shown that hunting has seriously depleted the population of some mammal species around SACHA and CAPH, particularly the large primates such as the red howler and brown capuchin and the large ungulates such as the tapir and white-lipped peccary. Total primate biomass was also affected in a similar way. Hunting pressure was high in the areas of forest used for tourism at SACHA and CAPH largely due to the ease of accessibility from nearby settlements and the lack of agreements between the lodges and local hunters regarding rights of access to the forest and trail system and related land-use issues concerning natural resource utilisation. As a consequence of hunting, species richness has declined around lodges located near settlements.

Although hunting is an important impact variable for some species there is still persuasive evidence to suggest that two persecuted species are impacted upon negatively (brown capuchin) and positively (red howler) by tourist traffic. However, further studies of these species would be required in order to determine if they would still show signs of tourist impact in the absence of hunting.

Lodges situated close to settlements would do well entering into discussions with local hunters, as well as other forest users, regarding land-use zoning and the provision of incentives to reduce or eliminate hunting pressure in forest areas visited by tourists. Some species may also benefit from a reduction in trail–use intensity where hunting is or has been prevalent.

The track study provided more information on the relative abundance of predators than the transect surveys. This was especially the case for the more nocturnal and cryptic forest cats such as the ocelot and jaguar. Track data provided plausible evidence to conclude that these cat species are negatively affected by hunting at SACHA and CAPH, however there is also evidence to suggest that relatively high trail-use intensities are also detrimental especially where hunting is or has been prevalent. The lodge with the highest predator species richness and abundance was the TRC, where hunting is absent and traffic levels are at their lowest. Whether or not increasing traffic at the TRC will affect the carnivore community in the future, either directly or indirectly, is still not certain although precautionary measures should be taken to monitor all major predator and prey species and adapt trail-use accordingly in the future.

The community of keystone fruiting trees was dominated by the Iriartea palm, which in some lodges accounted for up to 90% of the trees studied. There are indications to suggest that this palm, due to its usefulness as a construction material, has been depleted in areas close to human settlements. The abundance of the squirrel monkey appeared to be closely associated with the abundance of fruit trees from lodge to lodge, as was the biomass of the ungulate community.

The study of forage scrapings revealed that many terrestrial mammals forage significantly less often near tourist trails, in some cases by as much as 80%. The reasons governing this reduction are not related to fruit tree availability and are likely a consequence of 1) higher predation levels near trails, cats for instance have been shown to be attracted to man-made trails along which they frequently walk, 2) timidness when confronted by tourists moving along the trails and their associated lingering human odours, and 3) insufficient ground cover near trails for animals to hide from predators and tourists.

With regards to the impact of trail-use by tourists on other species the study revealed that the red brocket deer (M. americana) consistently vacated the area near tourist trails, although the scale of the impact we consider to be very localised and is probably restricted to areas up to 200m away from the trails. This species was generally less abundant at the TRC than at other lodges although this is likely due to the higher predation levels at the TRC as a consequence of the greater abundance of jaguars, the main predator of deer.

Other species that were shown to be significantly influenced by trail-use and/or were very sensitive to changes in the magnitude of trail-use were generally small in stature, for instance rodents such as the bolivian squirrel (S. ignitus) and southern amazon red squirrel (S. spadiceus), and primates such as the saddleback tamarin (S. fuscicollis) and there is also a case for the squirrel monkey (S. boliviensis), although as mentioned above there are indications that this latter species is most strongly influenced by fruit tree abundance. The red squirrel and the tamarin were observed to double or even triple their normal abundance levels at those lodges which have been established the longest and which have consequently exposed the forests bordering the trails to a high degree of traffic over a long period of time. The mechanisms behind this increase are associated theoretically with reduced predation levels, lower inter-specific competition for resources with larger mammal species, high reproductive rates relative to other species and a greater propensity of habituation to tourists.

For those lodges interested in reducing the effects of current or future traffic induced impacts we have identified five indicator species 1) red brocket deer, 2) bolivian squirrel, 3) southern amazon red squirrel, 4) saddleback tamarin, and 5) brown capuchin. An analysis of the difference in their abundance between T and C or their trend in abundance with increasing trail-use intensity suggests that optimal levels of tourist traffic should not exceed 696 people per year for any stretch of trail. In Chapter 7.0 we describe a simple model of trail-use management, based on experimental alteration of tourist traffic in conjunction with continued monitoring of these indicator species. Those lodges or institutions which require further guidance on monitoring their wildlife and implementing this trail-use management system should contact the authors (see Appendix 3 for correspondence details).