UCB Moorea Class: Biology and Geomorphology of Tropical Islands

Animals must be locally adapted to their habitat to optimize use of available resources. In highly variable environments, behavioral change allows animals to optimize resources quickly enough to keep pace with their environment (Luttbeg 1999). The factors that determine the animal's behavior are often difficult to uncover. Coris gaimard (Quoy and Gaimard 1824), a species of wrasse, exhibits different foraging frequencies across its range. This study attempts to determine what biotic factors may affect the foraging behavior. The study compares the behavior of two populations of C. gaimard in two similar lagoons around the island of Moorea, French Polynesia and a population in a previous study done in Japanese waters (Shibuno et al. 1994). Standardized timed observations from Moorea showed an increase in the amount of foraging behavior at the site with a smaller prey base. The behaviors, however, maintained the same relative frequency as the behaviors seen in Japanese waters where the prey base was larger, but had a different species composition. These observations indicate that prey quantity determines the amount of foraging, but the type of available prey determines the foraging strategy. Additionally, C. gaimard engages in heterospecific feeding relationships, but the presence of other foraging species does not significantly affect its foraging behavior. These results indicate that prey populations are a mjor biotic factor in determining foraging strategies.