Identify the type of migrants by their behavior in the following statement: When young males of many herd-mammal species grow up, there are already too many reproductive males present in a herd, so they travel in groups until they find new herds to join.

MCQs on the evolutionary history, phylogenetic relationships, comparative anatomy and physiology, and ecological interrelationships among animal taxa, as well as the evolutionary pressures that led to physiological and ecological differences among species and groups.