We've all heard of the boomerang kid—the 20-something who returns from college to live in their parents' basement—but does that happen in nature?
Not too often, but there are a few species who stick around mom for a long time—or even their whole lives.
Take the orangutan, which tends to do everything slowly, including leaving home.
The great apes give birth only once every seven to eight years, and the youngster will sometimes nurse until six years old—about the time a new baby comes along, says Helen Morrough-Bernard, a primatologist at the U.K.'s University of Exeter.
Most orang moms let the older offspring stick around for up to three years after the infant is born, while some chase the juveniles off after six months. (Read why animal mothers remind us a lot of our own.)
When the new arrival comes, the older sibling will “go off exploring on their own and may stay out overnight,” Morrough-Bernard says.
“I like to think of this as like a teenager going off to university and coming back in the holidays. They are not truly independent but are trying out their independence.”
Girls, girls, girls—the African elephant world revolves around them. The oldest, largest female is the typically the leader, and females stay with their natal herd their whole lives.
Males leave their family group between age nine and 18, and since a wild elephant’s lifespan is about 56, that could mean nearly a third of his life is spent at home. (Related: "Wild Elephants Live Longer Than Their Zoo Counterparts.")
Like in elephant society, female lions "are the stable social structure of the pride, and it’s the males that come and go, taking over prides,” says Ed Spevak, curator of invertebrates at the St. Louis Zoo who has also studied African animals.
Males always disperse for other groups in this fission-fusion society, and about one-third of femalees will go off to other prides.
By and large, though, Spevak says, “you could have some sisters and daughters staying with each other for the rest of their lives.”
Orcas are born into tight-knit, female-led family groups called pods. Females stay in the pod their whole lives, while males leave only to mate and then eventually return.
Females may live up to 90 years, well past reproductive age, likely because it helps their grown sons survive. Older female orcas support their male offspring by helping them find food or defending them in skirmishes with other killer whales, according to New Scientist. (Related: "After Menopause, Female Killer Whales Help Pod Survive.")
A 2012 study found that male orcas over 30 were three times more likely to die within a year after their mother's death if she was of reproductive age. The risk increased 14-fold if she was over 30. Mothers’ deaths had much less impact on their daughters' survival.
Several species of these tiny South American primates live in small family groups, which include "teenagers" of both sexes that stay on to babysit their younger relatives, says Don Moore, director of the Oregon Zoo in Portland. (See National Geographic's pictures of animal mothers and babies.)
This ensures the juvenile tamarins learn how to raise their own offspring successfully, Moore says. Young adults and adults then migrate to different groups to find mates.