There are many different names for bird groups, and what they are called depends on the species. A group of hens is called a brood, while a group of penguins is a colony. A group of geese is called a gaggle, and a group of quail is called a bevy.
A group of herons is called a siege, and a group of finches is a charm. A group of hawks is called a cast, a group of pheasants is called a nye, and a group of snipe is called a wisp. A group of swallows is called a flight. Some species of birds are solitary and never flock together.