Burying Beetle Mom: Conscientious Cannibal?
Mother's Day honors the bond between mom and child, but many animal mothers are more Mommie Dearest than Mom of the Year--at least at first glance. Take the burying beetle ...
She's a "bad" mom because ... she eats her young in a deadly game of musical chairs.
Burying beetle larvae typically move into a mouse carcass their mother and father have buried. The mother feeds her young by eating the carcass and regurgitating the mouse meat.
"The little larvae wave back and forth, begging to mom," said Scott Forbes, University of Winnipeg biologist and author of A Natural History of Families.
"The first ones get fed, but the very last one sitting there begging [after the portion runs out] gets eaten by the mother."
Give Mom a break, because ... burying beetle mothers are likely culling their brood to match the food supply. The beetles typically produce broods bigger than the carcass can support. A bit of strategic cannibalism boosts overall survival chances for the larvae left "standing" when the music stops.
Giant Panda Mom: Playing Favorites, Fatally?
She's a "bad" mom because ... panda mothers sometimes have two babies--but they rarely raise more than one.
"Pandas have good press, but they [can be] bad moms," Forbes said. Pandas' second offspring, helpless and about the size of a stick of butter, are typically left to their fate in the wild.
Give Mom a break, because ... As the "favored" offspring gets bigger, he or she takes a lot of attention and eats a lot of bamboo. Mothers probably wouldn't be able to provide for two offspring during the eight to nine months until they are fully weaned, Forbes said.
"One robust offspring is probably better than two weak ones later on," he said, "so the quality control occurs early on when it's cheap before you've invested lots of resources."
Hamster Mom: Again With the Cannibalism?
She's a "bad" mom because ... despite their cuddly appearance, hamster moms can be cold-blooded killers—they often eat their own young.
Give Mom a break, because ... she was planning for the best, and now she's just dealing with the rest.
Forbes believes hamster moms practice "parental optimism" by creating broods bigger than they may be able to rear.
"They don't know how much food is going to be out there," he said. "They create a litter with a few spare offspring to ensure high-quality young even if [food is scarce] or there are developmental defects in others."
Black Eagle Mom: Can't Be Bothered
She's a "bad" mom because ... she won't stop sibling squabbles--even though they often turn deadly.
Black eagle nest mates have violent battles, Forbes said, "and the parents just stand by as the oldest sibling murders the youngest.
"It's infanticide by proxy--a cooperative arrangement between the older sibling and the mother, who is perfectly happy to watch."
Give Mom a break, because ... though their indifference seems unconscionable, the eagles are practicing something seen in many bird species. The deadly sibling squabbles likely help to allocate food resources and ensure the survival of the fittest offspring.
As is often the case with apparent neglect among animals, Mom may not be minding the kids, but she does seem to be looking out for the species.
Hooded Grebe Mom: Favoring the Firstborn
She's a "bad" mom because ... she abandons "castaway" chicks. Mother grebes build floating nests of rotting vegetation where both parents incubate two eggs until one hatches.
But "once that first chick hatches, [the parents and baby] swim away from the nest and leave the other chick all by its lonesome," Forbes explained. "They are just interested in getting one successful chick off the nest."
Give Mom a break, because ... grebe mothers are simply producing an "insurance offspring"--at least one baby will survive even if there's a problem with the primary chick. "It's pretty routine in large predatory birds," Forbes noted.
Long-Tailed Skink Mom: Self-Absorbed Pessimist?
She's a "bad" mom because ... even though "Mother of the Year" candidates are scarce among reptiles, this lizard is a standout among callous moms. If the skink mother lays a clutch of eggs when there's lots of predators around, she's likely to eat her brood before they hatch.
Give Mom a break, because ... the skink is probably saving her young from an inevitable fate while making herself stronger to ensure another chance to reproduce, Forbes said.
"She may decide that because of all the predators, there is no chance of her eggs making it, so she's going to eat them to recycle the nutrients."
Rabbit Mom: Absentee Parent
She's a "bad" mom because ... rabbit mothers abandon their young in burrows immediately after birth and return to feed them for only about two minutes daily during their first 25 days. After this brief bout of "drive-by" parenting, young rabbits are left to fend for themselves.
Give Mom a break, because ... rabbits are tasty, and predators especially enjoy feasting on helpless newborns. Mothers likely avoid their young to keep their underground locations secret--and their precious progeny alive.
Though mother-child "quality time" is limited, increased odds of survival may be the greatest gift of all--a little something to remember this Mother's Day 2009.
No comments:
Post a Comment