UCB Moorea Class: Biology and Geomorphology of Tropical Islands

Social structures and population ecology can greatly influence individual behaviors in animal societies. The Common Myna (Acridotheres trisis) is a social, aggressive bird that is known as one of the world’s worst invaders. On the island of Mo’orea, French Polynesia,A. tristisis most often found in pairs and groups. It was anticipated that a pair ofA. tristiswould act as a team to increase foraging and defense efficiency. This study examined aggressive behaviors using behavioral observations ofA. tristisin pairs and groups on two different sites on the island. Food was added to the sites to determine how food availability may affect behavior. The results show that being in a group setting significantly increases aggression. A look at non-aggressive behaviors provided information on the most common behaviors seen inA. tristisboth in groups and pairs. Furthermore, the addition of food significantly increases aggression. The aggressive behaviors seen were increased with group type and food availability. These behaviors could be mediating the invasive nature of this bird.