Along with its darling buds, the month of May features Mother's Day. The holiday is a time for Mom to be feted by her own darlings—because all us buds were brought into this world by a mother. But the human mother-child relationship is just one small slice of what nature has ordered up over the course of evolutionary time. The oddball (to us) ways of some other mothers—mostly mammals, but with a smattering of fish, reptiles, amphibians and birds—are illuminated in the new book Wild Moms, by biologist and author Carin Bondar.
In short, it can be a jungle out there.
For example, Bondar devotes a section to “cooperatively breeding mammals.” In these species, the care of newborns is shared among the group. Some extreme cases involve meerkats, naked mole rats and selected primates that have come up with lifestyles that relegate most females to the role of caretakers while elevating a single female for baby making.
Those pop-up protagonists, meerkats (which are not cats but a kind of mongoose, which is not nearly a goose) have a system in which only about one in six females can ever ascend to baby-bearing status. Bondar compares it to the movie Mean Girls, except there's no “Spring Fling” dance at the end where everybody makes up.
Adult female meerkats who don't become queen wind up as her ladies-in-waiting. They spend their lives, Bondar writes, in “foraging, nest- and home-building, defense of the group from predators or competitors, babysitting, and allonursing, or wet nursing.” It's good to be the queen.
Many of the ladies are the queen's close relatives, including sisters and daughters. And every once in a while one of these subordinates violates the rules in the implicit meerkat manual: she picks up a suitor on the sly and gives birth. Queens, who, as Bondar notes, “undergo a secondary growth spurt once they obtain a breeding position and are therefore of considerably larger size than submissives,” will kill these pups—even though they may be the queen's own grandchildren. And you thought Shakespearean royal families were rough on each other.
Naked mole rats keep a much lower profile than meerkats do—they live in underground tunnels. Nicknamed “saber-toothed sausages,” the critters engage in better living through chemistry: queens avoid committing familial infanticide by producing hormones released in their urine that stunt the development of the other females, rendering them incapable of having kids.
The sausage sovereign thus can concentrate on getting pregnant, giving birth and caring for her litter until the pups wean. And for the first two weeks postpartum, that care requires that she produce half her own body weight in milk every day. Before long, she's cooking up a new batch of the more than 900 babies she'll give birth to during her life. At an average of a dozen per litter, that's about 75 pregnancies. Eh, maybe it's not that good to be the queen.
Meanwhile, up in the sky, bats lead a much more egalitarian existence than do meerkats or mole rats. No Big Mama forbids anybody else to reproduce, and they care for one another's offspring in communal roosts. One reason for that behavior may be aerodynamics.
Like the mole rat, a female bat may produce half her body weight in milk every day. Unlike the mole rat, she needs to fly to forage. And to get clearance from the tower, she has to be streamlined. Which means dumping excess milk. As bats have yet to invent teeny tiny breast pumps, the mother's best option is to share her milk supply with the offspring of her roost mates. That arrangement also virtually guarantees some extra calories for her own pups from the other bat moms. Humans do a version of this arrangement, but they use cow's milk and call it a dairy cooperative.
Speaking of humans, give your mother a call if you can and thank her. Both for raising you and for being far less wild than a lot of other moms out there.