Studies of Tropical Vertebrates- Ecology, Behaviour and Morphology

Samual Williams MRes thesis

ABSTRACT

The ecology of the Buton macaque (Macaca ochreata brunnescens) is poorly understood, and its status and habitat preferences have not been previously investigated. The aim of this study was to determine the population density and population size of the Buton macaque in the forests of central Buton. The habitat requirements of the species were also investigated. Data collected indicate a population density of 14.9 Buton macaques/km2, and a current population size of 3,752 within the protected forests of central Buton. This is likely to be viable in the long- term. No habitat preferences could be identified, although the current habitat appears adequate.

Howler monkeys (Alouatta spp.) were studied in Honduras with the aim of identifying the species present and characterising its activity patterns. There is dispute over the identity of the howler monkey species occurring in Honduras, but morphological and behavioural data presented here indicate that the species present in the Cusuco National Park, Honduras, is A. palliata. A new, molecular, species identification technique using non-invasively collected DNA samples extracted from faeces was also employed, although this was unsuccessful. Differences were observed between the activity budgets of male and female howler monkeys, which could be explained by their different social roles. However, the sample size of the study was relatively small.

The eye morphology of the tree frogs Agalychnis calcarifer and A. craspedopus, is unusual within the genus Agalychnis. The iris of these two species displays apparent metachrosis (colour change) as the eye opens, a phenomenon which is unreported in amphibians. This study uses a new technique involving digital image analysis to quantitatively assess this process, and to determine the mechanism by which it occurs. Observations suggest that the visible colour of the iris is modulated by revealing different areas of the iris as opposed to redistributing pigment. The eye morphology of A. calcarifer and A. craspedopus was also described in relation to other Agalychnis frogs. The advantages and limitations of digital image analysis as a morphometric tool are discussed.