The Curious Case of Grey Seals and the Underwater Clap

Background

The grey seal (Halichoerus gryphus) is a member of the Phocidae family, or “true seals”. As a member of Phocidae, they do not have ear flaps and they propel themselves with their hind flippers. Grey seals live only in the North Atlantic Ocean and are separated into three distinct populations, or “stocks.” Generally, grey seals live between 25 and 35 years, with the females living slightly longer than the males. Female grey seals reach sexual maturity when they are around 4 years old and then give birth once a year. The pups are born during the breeding season, when large groups of grey seals haul out onto land or ice. All parental care is provided by the female, but males protect the females during birth. Traditionally, seal communication has been thought to be a means of sharing information throughout the social breeding season. Their main vocalizations consist of hisses and growls, especially between males competing for a female. The seals also use physical cues such as neck darts and opening or closing their mouth. In the past, seals in human care have been prompted to clap, but this study is the first time that they have been observed clapping in the wild.

Observations

In October 2017, a camera caught footage of a male grey seal making percussive actions. This took place near the Farne Islands in the Northeast of England. In the video, a wild male grey seal approaches a female seal. The female seal communicates with a “guttural rup.” The male seal hits its front flippers together to make a loud clap, and a few seconds later a reply clap comes from another male out of frame. In response, the initial male claps twice more. The male seal outside of the frame claps back. Later, the female returns, prompting another two claps and a pursuit for the female. After the chase ends, the male then makes a final single clap and a “guttural rup.” 

Significance

This video marks the first time in which clapping behavior has been recorded among grey seals, and it is particularly interesting that the clapping elicits a response from nearby seals. While this video footage is still anecdotal and lacks more supporting examples, it strongly suggests that clapping serves an important social function among grey seals. From a scientific standpoint, claps have a greater sound frequency range than other vocal signals and also match up with optimum hearing sensitivity among phocids, so this could be an extremely effective method of communication in noisy waters. The lead author of the study compares the clapping behavior to the chest beating of a male gorilla, hypothesizing that their purpose may be to discourage competitors and simultaneously attract mates by serving as an indicator of strength. Naturally, being cognizant of this behavior and its implications for grey seals’ survival is crucial when designing future regulations around human generated sound profiles in the ocean.

Conclusion/Further Research

While scientists note that “clapping” behavior has been observed frequently in seals in zoos and aquaria for the entertainment of its guests, this is the first time researchers have recorded wild seals performing such an action underwater. Although there is currently no concrete evidence for the motivation or purpose of these behaviors, researchers believe that male grey seals use the mechanism to ward off competitors and/or attract mates. However, more behavioral studies and observations are needed to confirm this explanation or even the concrete existence of this behavior. Regardless of the reason for these percussive claps, this data acts as further evidence for the importance of auditory behaviors in marine mammals, including grey seals. Therefore, anthropogenic noise pollution from boats and other sources could possibly interfere with these mammals’ communication. Due to the grey seals’ proximity to the surface, human noise pollution could have, and possibly already has had, adverse effects on the seals’ social behaviors. More research is needed to determine if and how this noise pollution interferes with the grey seals and what could be done to prevent it. 

Main Sources:

News Article: https://phys.org/news/2020-02-grey-underwater.html

Dropulich, Silvia. “Grey Seals Discovered Clapping Underwater to Communicate.” Phys.org, Phys.org, 3 Feb. 2020, phys.org/news/2020-02-grey-underwater.html.

Research Paper: https://onlinelibrary.wiley.com/doi/full/10.1111/mms.12666

Hocking, David P., et al. “Percussive Underwater Signaling in Wild Gray Seals.” Marine Mammal Science, 31 Jan. 2020, doi:10.1111/mms.12666.

Other References: 

Bowen, D. 2016. Halichoerus grypus . The IUCN Red List of Threatened Species 2016: e.T9660A45226042. https://dx.doi.org/10.2305/IUCN.UK.2016-1.RLTS.T9660A45226042.en. Downloaded on 25 February 2020.

“Gray Seal.” NOAA, www.fisheries.noaa.gov/species/gray-seal.

“Gray Seal.” Oceanwide Expeditions, oceanwide-expeditions.com/to-do/wildlife/gray-seal.

“Gray Seal.” Smithsonian’s National Zoo, Smithsonian, 26 July 2018, nationalzoo.si.edu/animals/gray-seal.

“Grey Seal.” Ecomare, Stichting Texels Museum, www.ecomare.nl/en/in-depth/reading-material/animals/seals/grey-seal/.