Most of the time, YES. The most common reason an animal enters the attic of a home is the have a safe place to give birth to and raise a nest of young. Almost every time, a raccoon or a squirrel in your attic is a single female, who will soon give birth to a litter of 3-5 babies. Many people do not even realize they have animals in their attic until these young start to make noise. Baby raccoons, for example, have a distinct vocal chatter. Baby squirrels grow very quickly, and are near adult size within six weeks, at which time your attic has been transformed from a place with one active squirrel to five active squirrels, and you really notice it then! This nest of babies is a matter of high concern. You can't simply trap and remove the adult female and leave the nest of young behind. Depending on their age, they will scratch and claw, and if they can't get out and then die, they will rot and stink. It is extremely inhumane to leave the nest of babies behind. Most of the time, they must be removed by hand. In addition, birds, rats, mice, opossums, and especially bats enter an attic and rear young. Read more about nest of baby animals in the attic.