Behavioral characteristics may play a key role in the establishment and spread of alien animal species, and the understanding of many animal invasions often requires a careful assessment of behavioral mechanisms. Since 1980s, animal invasions have intensified all over the world and studies on behavioral mechanisms connected to successful animal invasions have received more attention. Some invasive animals show flexibility in intraspecific aggression and feeding behaviour, which allows them to effectively cope with the changing environment. Thus, behavioral flexibility makes critical contributions to population establishment and persistence. Successful invaders often exhibit advantages in behavioral interactions over indigenous species, and such may contribute to the displacement of indigenous species. Such behavioral mechanisms also play an important role in their spread. The longdistance dispersal behavior of invasive animals can increase invasion rates. Many behavioral characteristics can enhance invasion success by coupling behaviors with dispersal strategies that are especially important during natural range expansions. The few successful studies to date indicate that behavioral analyses should be more actively and fully integrated into research on biological invasions. Understanding the behavioral mechanisms in animal invasions will improve our ability to predict invasion of alien species and manage biological invasions more effectively. In addition to enhancing a general understanding of invasion processes, such approaches provide potentially unique opportunities for basic research in animal behavior as well as the significance of behavioral interactions in species evolution.