The phrase "in flocks" refers to a large group of animals or birds that are together in a particular location. There are several synonyms that can be used to describe this phenomenon, including "in packs," "in groups," "in herds," and "in swarms." "In packs" is commonly used to describe animals like wolves or coyotes, while "in groups" is more general and can be used to describe any large gathering of creatures. "In herds" is typically used to refer to grazing animals like cows or sheep, and "in swarms" is commonly used to describe insects like bees or locusts.