In a new study from the University of California Santa Cruz, the researchers found that mother elephant seals can recognize their pup’s voice at just two days old. The experts said this helps mothers and babies survive during a precarious time.
An international team of scientists led by Dr. Juliette Linossier recorded calls of elephant pups using a microphone on the end of a long pole. The recordings were played to mother elephant seals as their responses were monitored. The moms were played calls from their own babies, as well as calls from a pup of a similar age.
The study revealed that the mothers were much more interested in the speaker and moved toward it when it was playing calls from their own pup.
“This is a rare demonstration of individual recognition among phocid mothers and their offspring, and suggests that consistency in maternal responsiveness may be an important social factor influencing the pup’s growth and survival,” wrote the study authors.
While feeding newborn elephant seals, the mothers lose about half of their body mass. Meanwhile, the pups gain about seven times their initial weight. This substantial weight gain can be attributed to the “exceptional fat content” of the mother’s milk.
While the early recognition is necessary for survival, the researchers could not explain why female seals are often observed feeding each other’s pups.
“Females fast for the entire month they are nursing,” study co-author Dr Caroline Casey told BBC. “So it makes no (evolutionary) sense for them to use their resources on another mother’s pup.”
“But at this site (a colony in California) that we study, there have been a lot of observations of females feeding pups not related to them.”
According to Dr. Casey, it is possible that humans are to blame. She noted that elephant seals were hunted to near extinction during the late 1800s. As a result, the tens of thousands of elephant seals that are alive today can be traced back to just a couple dozen seals that historically survived.
This phenomenon would make the elephant seals genetically similar, which may explain why mothers would feed other pups if the their moms are closely-related females.
Going forward, the researchers want to investigate whether the seals are more likely to feed the pups of their sisters or cousins.
The study is published in the journal Royal Society journal Biology Letters.