By Stephen Beech
Male elephant seals can recognize rivals from years ago, reveals new research.
They responded to recorded calls of old enemies in a study that American scientists say shows that humans are not the only animals that can remember the voices of former acquaintances.
Professor Caroline Casey and her team have spent over a decade studying the seals on Año Nuevo Island off the coast of California.
They observed male elephant seals engaging in dominance displays year after year.
It led them to wonder if the seals remembered their past bouts.
Casey said: “Male elephant seals come back to the exact same breeding location year after year and engage in competitive interactions with a number of familiar individuals.
“It would make sense, then, that they would retain some memory of past rivals over multiple seasons.”
To test the theory, the team would find a male seal returning to the island at the start of the mating season and play recorded calls from his old rivals.
Casey, of the University of California, Santa Cruz, said: “When males heard their most familiar dominant rival from last year, they tended to orient faster, exhibit a faster posture change, and often would retreat from the speaker.
“Their responses were less severe when they were presented with their subordinate rival from the previous season, and sometimes they would even approach the speaker.”
The team also played calls recorded at other colonies, observing that the unfamiliar calls elicited a much smaller response from the seals.
The researchers say that discovery proved that the seals were not just responding to random strangers but actually recognizing and remembering individuals they had met the year before.
The team is continuing to study elephant seal reproductive behaviors.
Casey added: “Right now, we are working on a project evaluating the traits that lead to eventual reproductive success in male elephant seals.
“Essentially, what does it take to become an alpha seal? We are measuring lots of different aspects of behavior and physiology and linking it to true reproductive success in this species.”
Casey is due to present her team’s research on elephant seal memory at a joint meeting of the Acoustical Society of America and Acoustical Society of Japan in Honolulu, Hawaii.
