Joanna Moon/Sun Graphic Designer

May 11, 2021

Animal Kingdom Mothers Sacrifice Resources to Raise Young

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While human mothers received elaborate bouquets or harried text messages for Mother’s Day, the other mothers of the animal kingdom dealt with the threat of predators and scrounged for food to feed their young. 

To shed light on mothers across the tree of life and their dedication to taking care of their children, The Sun spoke with Cornell professors who offered a glimpse into the lives of animal mothers.


While it’s customary for human mothers to be treated to breakfast in bed or a fancy dinner, spider moms in the genus Stegodyphus become food for their children. For the first few weeks after her eggs hatch, a mother regurgitates food for her spiderlings before being eaten alive herself, according to Prof. Michael Webster, neurobiology and behavior. 

“When the young hatch, she will secrete this really nutritious stuff [from] her joints, and the young feed on that,” Webster said. “But then as they get bigger, they start to actually consume the mother herself. They’ll eat her legs, and by the time they’re all grown and ready for independence, she’s dead, and she’s sacrificed her entire life for her offspring.”

This maternal sacrifice, which may seem strange to humans, is an evolutionary tactic to better the odds of the spiderlings’ survival, according to Prof. Linda Rayor, entomology. 

“It provides a really massive amount of prey to the youngsters that they’re able to eat for a while. And it gives them a head start in life,” Rayor said.  

Polar Bears

In the harsh and unforgiving Arctic, polar bear mothers go months without food and put off birth to provide the safest conditions for their newly born cubs. To ensure that their young enter the world in survivable conditions, polar bear mothers can “schedule” birthing by pausing their embryo’s development for four months after the spring mating period. 

This four-month pause also allows mothers to pack on hundreds of pounds to prepare for birthing and raising their pups. They spend the winter in dens, where they give birth and protect their helpless cubs from the harsh cold. 

During this period, mothers stop eating, drinking, urinating and defecating to conserve energy for making milk for their cubs. 

Come springtime, mothers emerge from their dens and eat their first meals in almost six months. A polar bear mom will use the next two and a half to three years to teach her cubs to hunt and fend for themselves, all the while protecting them from predators like wolves and adult male polar bears. 

Emperor penguins

For the emperor penguin mother, finding dinner is no trip to the grocery store — she must journey for two straight months, avoid predators and trek and swim up to 900 miles to find food for her young, according to Prof. John Fitzpatrick, ecology and evolutionary biology, executive director of the Cornell Lab of Ornithology.

Fitzpatrick explained that emperor penguins huddle together in massive colonies to maintain their heat against Arctic wind chills of minus 76 degrees Fahrenheit. After a mother penguin lays her egg and leaves it in the care of the father, she must venture out of the colony to forage for fish and store the fish “goop” in her belly.

Within a week of her egg hatching, the mother makes it back to the colony, identifies her mate among hundreds or thousands of other penguins and begins to regurgitate the food she stored to feed her new young, Fitzpatrick said.

Meanwhile, the father penguin has gone without eating for two months, so he hands off the baby penguin to the mother and makes the same voyage out to gather food for his family.

“The female does these heroic trips and foraging ventures to provide the first round of food for the babies when she comes back,” Fitzpatrick said. “[The male and female] take turns doing that, to be able to raise these young.”


Instead of having to traverse land and sea, some mothers seclude themselves with their young to protect them.

According to Webster, mothers in some species of hornbill form their nests in tree hollows — cavities in tree trunks. Upon entering the hollow, the female bird works with the male to seal the cavity with mud, drying into a cement-like wall with only a tiny slit opening to the outside world. This cement can keep out predators, while also guarding the cavity from being taken over by other birds, Webster explained.

The female — fully enclosed within the cavity — lays her eggs and stays in the enclosure until her young hatch, grow up and are ready to leave the nest, Webster said. 

“The female is in there for weeks and weeks with the young. She loses all her wing feathers because she doesn’t need to fly, because she’s trapped,” Webster said. “The male brings food and passes it to her through a little slit for weeks. That’s pretty extreme maternal devotion, I would say.”

Fitzpatrick said that while people don’t normally appreciate the dramatic lives of animal mothers, a diversity of animal life lies at the heart of a healthy climate, sustainable ecosystem and a thriving, interesting planet.

“Why should we care? Because the world is so interesting with them,” Fitzpatrick said. “It would be so incredibly boring without them.”