The Nutritional Ecology of Spider Monkeys (Ateles chamek) in the Context of Reduced- Impact Logging

Abstract

Selective harvesting of timber in tropical forests can remove substantial amounts of primate food sources, resulting in significant reductions in population densities. As frugivorous primates are important seed dispersers in tropical forests, it is crucial for long-term ecological sustainability to maintain their populations within forestry concessions. One way of achieving this goal is to gather relevant information regarding the importance of commercial timber tree species in the diet of seed dispersing primates and ultimately suggest adjustments to timber extraction rates to minimize detrimental impacts on primate food resources. In this thesis I first describe the diet and temporal patterns of food consumption by the Peruvian spider monkey, Ateles chamek, inhabiting a semi-deciduous moist forest that is incorporated in a certified forestry concession in lowland Bolivia (Chapter 2). I then determine what governs their diet selection (Chapter 3), and analyse how this nutritional strategy influences seasonal diets and the resultant nutritional states of individuals, and estimate the relative value of different food sources (Chapter 4). These threads of information are combined to assess the importance of timber tree species in the diet of these primates as a basis for recommendations for forest management and primate conservation (Chapter 5). As such, an overreaching aim of this thesis is to contribute to the understanding of the effects of certified tropical forestry on biodiversity conservation.

Six general conclusions arise from this thesis:

1. Feeding ecology of Ateles chamek in La Chonta differed from other documented spider monkey diets because of the dietary dominance of ripe and unripe figs.

2. Diet selection was governed by protein-dominated macro-nutrient balancing, rather than energy or protein maximization, or avoidance of plant secondary metabolites.

3. The food intake strategy employed by individuals and their resultant nutritional state depended upon the seasonal availability of different foods. Due to seasonal availability of fruits rich in soluble carbohydrates and lipids, intake of these macro-nutrients was 50% higher during peak fruiting season than during the period of fruit scarcity.

4. Figs were nutritionally-balanced foods for spider monkeys, and the inclusion of a diverse array of ripe fruits in their diet appeared to be used as a strategy for persisting through times of fig scarcity.

5. Timber tree species provided spider monkeys with 50% of their macronutrient intake, comprised their staple food, and dominated their peak season and fall-back diets.

6. Under current prescriptions for timber extraction the spider monkeys in La Chonta are expected to lose significant proportions of their food sources. This is a likely explanation for the observed declines in population density post-logging. Harvesting limitations should be considered for the timber tree species Ficus boliviana, Spondias mombin and Pouteria nemorosa. Show more