By: Holly George
Signaling and communication is a fundamental and critical function for most, if not all, species on earth. Now more than ever, we as humans are realizing the importance of communication and social relationships as we cope with a pandemic that affects how we socialize with one another. There are many different ways in which species communicate, most of which are highly dependent on circumstance and vocal ability. When it comes to the world’s oceans, many species rely on acoustic calls or cues to communicate with one another. Orcinus orca, commonly known as orcas or killer whales, are highly social animals that produce vocalizations in the form of whistles, pulsed calls, low-frequency bellows, jaw claps and echolocation clicking. Orcas create these sounds by the movement of air between nasal sacs within the whale’s blowhole, as orcas do not possess vocal cords like we do.
Not only can orcas communicate in a highly developed way, they are also one of few mammalian species with true dialects. Dialects are a form of regional accent specific to a certain social group and are the result of social learning of group-specifics calls. In the case of orcas, each collection of calls within a given dialect is referred to as a repertoire, which may be shared in part among different social groups to form clans. Social groupings of orcas are called pods, which are made up of multiple generations and vary greatly in size. The formation and dynamics of a pod are influenced by ecotype, meaning whether the grouping is made up of resident or transient individuals. Resident killer whales are fish-eating organisms with pod sizes from 5-30 whales, whereas transient killer whales maintain a diet consisting of sea birds or other mammals such as seals and dugongs. Transient killer whales often form smaller pods, consisting of only 2-5 whales. Overall, the formation of these differing social groupings allow for communication and dialect to flourish among this captivating species in a truly incredible way!
Given the great complexity of orca communication and dialect, you may be asking yourself how and why this social pattern is developed. First and foremost, it is believed that social vocal behaviours are learned, not predetermined genetically, and even change culturally from generation to generation. These differences are most likely due to an innate ability to evolve and adjust to ever-changing stimuli. It is believed that young killer whales establish dialect through vertical production learning, meaning calls are modelled from mothers and other pod members. Dialect is then maintained as a result of needing to produce similar calls for social exchange and matching the calls of those around them. Killer whales begin with producing high-pitched, rambunctious calls that do not reflect mature calls until they are approximately 2 months old. From then on, repertoire increases greatly between 2-6 months, until finally call learning is largely accomplished by the time puberty takes place. Interestingly, family-specific calls increase following the birth of a calf, suggesting that these calls are critical for bonding and learning between mother and offspring.
The intelligence and complexity of social structure among orcas may make you question whether or not orcas are able to interact with other species that communicate in similar ways, such as dolphins. The answer to that question is not yet completely clear, however, by comparing orcas that had been exposed to bottlenose dolphins in the past to orcas exposed to only the calls of bottlenose dolphins, we have learned that contextual learning between species is indeed possible (Musser et. al, 2014). In fact, one killer whale learned to make chirping calls taught exclusively to bottlenose dolphins!
Finally, we must also remember our footprint and the impact of man-made equipment on the ocean environment. Elements such as ships, submarines, military sonar and other signaling structures within the ocean greatly influence the bioacoustics of many marine species, including orcas. According to a 2013 study, commercial shipping produces low-frequency chronic noise, which greatly impacts the ability of orcas to communicate, as this is the frequency in which most social whistles and calls are made. These artificial sonars and marine noise may be affecting the social well-being of not only orcas, but all species that rely on a stable acoustic environment as well. Given that a quiet marine environment is the means of communication for these marine animals, we must recognize and respect that by taking accountability for our actions and avoiding those with detrimental effects. When we think about our means of communication as people, especially now, we think of phone calls, video chat, and various other technologies. A loud marine environment to an orca is like a bad connection for us, and we all know how much that affects our ability to communicate!
Ultimately, it is our responsibility to ensure a safe and stable environment that allows for clear communication for our ocean friends. Together, we can take the steps to correct and prevent harmful actions, one conversation at a time.
Holly George is a BSc graduate from Memorial University and has been working with ocean education since the completion of her degree in 2017. She spent two seasons with the Bonne Bay Marine Station as a Marine Educator and was also a Youth Host with Ocean School, an online platform for ocean literacy. Holly currently resides in St. John’s, NL and works with the Petty Harbour Mini Aquarium. Holly is also a winter intern with CaNOE this season and she looks forward to continuing to spread the message of ocean advocacy and conservation.
Studies mentioned in this post:
Musser, W. B., Bowles, A. E., Grebner, D. M., & Crance, J. L. (2014). Differences in acoustic features of vocalizations produced by killer whales cross-socialized with bottlenose dolphins. The Journal of the Acoustical Society of America J. Acoust. Soc. Am., 136(4), 1990-2002. doi:10.1121/1.4893906
Williams, R., Clark, C. W., Ponirakis, D., & Ashe, E. (2013). Acoustic quality of critical habitats for three threatened whale populations. Animal Conservation Anim Conserv, 17(2), 174-185. doi:10.1111/acv.12076
Other papers to check out:
Crance, J. L., Bowles, A. E., & Garver, A. (2014). Evidence for vocal learning in juvenile male killer whales, Orcinus orca, from an adventitious cross-socializing experiment. Journal of Experimental Biology, 217(8), 1229-1237. doi:10.1242/jeb.094300
Deecke, V., Ford, J., & Spong, P. (2000). Dialect change in resident killer whales: Implications for vocal learning and cultural transmission. Animal Behaviour, 60(5), 629-638. doi:10.1006/anbe.2000.1454
Filatova, O. A., Deecke, V. B., Ford, J. K., Matkin, C. O., Barrett-Lennard, L. G., Guzeev, M. A., . . . Hoyt, E. (2012). Call diversity in the North Pacific killer whale populations: Implications for dialect evolution and population history. Animal Behaviour, 83(3), 595-603. doi:10.1016/j.anbehav.2011.12.013
Kremers, D., Lemasson, A., Almunia, J., & Wanker, R. (2012). Vocal sharing and individual acoustic distinctiveness within a group of captive orcas (Orcinus orca). Journal of Comparative Psychology, 126(4), 433-445. doi:10.1037/a0028858
Riesch, R., & Deecke, V. B. (2011). Whistle communication in mammal-eating killer whales (Orcinus orca): Further evidence for acoustic divergence between ecotypes. Behavioral Ecology and Sociobiology Behav Ecol Sociobiol, 65(7), 1377-1387. doi:10.1007/s00265-011-1148-8
Weiß, B. M., Symonds, H., Spong, P., & Ladich, F. (2010). Call sharing across vocal clans of killer whales: Evidence for vocal imitation? Marine Mammal Science, 27(2). doi:10.1111/j.1748-7692.2010.00397.x