Gabriela Orihuela

National Agrarian University · Department of Forestry Management

The harpy eagle (Harpia harpyja) is one of the main predators of arboreal mammals in the neotropics, affecting the ecology and behaviour these species. Knowledge of harpy eagle diets across their geographical range is patchy, the ability of harpy eagles to adapt to changing habitats is still open to question. The three main species in the diet of h...

Predators are a ubiquitous presence in most natural environments. Opportunities to contrast the behaviour of a species in the presence and absence of predators are thus rare. Here we report on the behaviour of howler monkey groups living under radically different conditions on two land-bridge islands in Lago Guri, Venezuela. One group of 6 adults i...

We studied diet choice by a generalist herbivore, the red howler monkey (Alouatta seniculus) under conditions of high and normal population density. Densities equivalent to 800–1000 km−2 (roughly 20–40 times normal) occurred in populations trapped on small, predator-free islands in Lago Guri, Venezuela. For three successive years, we studied one su...

The manner in which terrestrial ecosystems are regulated is controversial. The "top-down" school holds that predators limit herbivores and thereby prevent them from overexploiting vegetation. "Bottom-up" proponents stress the role of plant chemical defenses in limiting plant depredation by herbivores. A set of predator-free islands created by a hyd...