Humans have used song to serenade an intended mate since time immemorial. Could the same tactics work for other members of the animal kingdom? Leanna Matthews, a PhD candidate at Syracuse University in New York intends to answer just that. Matthews is studying how female harbor seals in estrus, the time that they are receptive to breeding, respond to recorded vocalizations of male harbor seals of differing maturities. Harbor seals are typically quiet, unlike the barking chorus of sea lions that greet coast-goers, and at most occasionally utter a grumble or growl.
Researchers know little about how marine animals communicate, and how sounds created by human activity affect their behavior. We know male harbor seals vocalize underwater during breeding season to establish territories, and some think these sounds may also help female harbor seals select mates,” Matthews said. Matthews hopes her research may help scientists understand how underwater noise from human activities may affect harbor seal breeding behavior in the wild.
To collect repeatable information, and minimize variables, Matthews could not answer her questions in the field. “My advisor has friends at the Hatfield Marine Science Center who said the Oregon Coast Aquarium has a lot of harbor seals,” Matthews said. The graduate student made arrangements, and flew out west for her first round of data collection. “I jumped at the chance to work with Leanna because it provides great opportunities to learn from the seals and provides them sound enrichment,” said Brittany Blades, a senior mammalogist at the Aquarium.
Enrichment activities and items provide animals with opportunities to learn and overcome challenges, or just experience something different from their usual routine. On the first day of Matthew’s study, Swap the harbor seal lazily paddled her stubby flippers around a pool behind the scenes at the Aquarium. A strange box had been introduced to her pool earlier in the week, and was now emitting noise recorded underwater, she paid it no mind.
A grumble disrupted her leisurely laps, and she popped her head out of the water. Spotting no other seals in her area, she dropped her head back below the water’s surface and quickly swam to the box that was the source of the sound.The other seal participating in the study, Boots, swam away from the sound of male vocalizations. Matthews was unsure of what to expect, “No one has played back male vocalizations to captive female harbor seals. There is so much we don’t know about their biology and just having access to them gives me an opportunity to explore something biologists have pondered for a long time.”
For her to draw conclusions about breeding behavior, she needs to be sure that her subjects are in midst of estrus, which happens only once a year for harbor seals. Matthews will return to the Aquarium for a second round of study over summer 2016. The recordings she plays to each seal include water noise, juvenile male harbor seal vocalizations, and mature male harbor seal vocalizations. In 2016, she will introduce those same noises to the same seals accompanied by new noises that may resemble human activities.
Information and photos by the Oregon Coast Aquarium
