A herd's a large group of animals and's a form of collective animal behavior. The term's usually applied to mammals, particularly ungulates. Other terms are used for similar phenomena in other types of animal. For example, a large group of birds's usually called a flock (this may also refer to certain mammals as well) and a large group of carnivores's usually called a pack. In addition, special collective nouns may be used for particular taxa: for example a flock of geese, if not in flight,'s s… (More on Herd)