One of the main reasons we enjoy dolphin and whale watching is the unique behaviour that we can see from the surface. Imagine the deafening splash from a 30,000 kg breaching humpback, the rainbow mist created when a blue whale blows and surfaces, and the graceful leaps made by a bottlenose dolphin bow riding. These surface behaviours are not only fun to watch, but more importantly, documenting dolphin and whale behaviour is critical for their conservation.
Being able to compare behaviour frequencies before and after an environmental disruption (ie, increased boat traffic, oil drilling, channel building, etc.) is essential in understanding human and environmental impacts on cetacean populations. However, behaviours must be consistently described in order to be useful to the scientific community. To facilitate consistent behaviour descriptions, scientists have established species specific ethograms, or categorized lists of described behaviours. This way, researchers across the globe can record accurate behaviour frequencies when sighting a cetacean. Ethograms typically consist of defined activity states (aka behavioural states) and behavioural events. Activity states are long duration behaviours such as foraging, whereas behavioural events are short duration behaviours that occur such as fish-whacking.
“With specific definitions of activity state categories and behavio[ural] event types, the [behaviour] of a species can be described, quantified, and compared across populations.”
Baker et al., 2017
Activity States
Cetaceans often perform a variety of behavioural events that fall within each activity state category. Activity states include socializing, feeding, resting, and travelling, and milling (swimming around with no clear direction). The repertoire of behavioural events within these activity states can be highly species and/or population specific. In this article, we’ll discuss behavioural events associated with socializing and feeding.
Behavioural Events: Socializing
Chasing, pectoral fin rubs, and breaching are all behavioural events performed by bottlenose dolphins and other cetaceans within the socialization activity state. Dolphins, especially juveniles, often “play fight” and chase each other for fun! Evidence shows that pectoral fin rubs may be used as a way to establish social bonds among members of a group. Breaching, or propelling through the surface, has been hypothesized to be for feeding, parasite removal, or socializing. Breaching exerts immense force along the surface, and some suspect that cetaceans use it as a means to stun their prey. That same force has been used by spinner dolphins and other species to remove bothersome ectoparasites like remoras. Cetaceans may also breach as a means to communicate. Kavanagh et al. (2017) found evidence that humpback whales use breaching as a means to prove their strength to other humpbacks.
Behavioural Events: Foraging
There are also a multitude of behavioural events associated with feeding and foraging. Dolphins have been seen fish tossing, fish-whacking, and fin jerking. After catching their prey, dolphins often throw them in the air. This behavioural event, known as fish tossing, is believed to be a way to stun or reposition a fish to be consumed safely. Similarly, fish-whacking involves a dolphin sending their prey high above the surface, this time using their powerful tails. This method stuns their prey for easier capture. If you see a dolphin’s dorsal fin jerk quickly in another direction, this could be evidence that they just caught a fish!
Cetaceans perform a variety of behavioural events. Documenting activity states and behavioural events are essential to make good decisions with regards to their conservation. You can contribute to that effort by recording behaviours you see on your Sea Watch sightings form! If you suspect that you saw a behaviour that is not an option on the list, be sure to include a detailed description in the “other comments” section. Including a photo or video of the behaviour can also help us identify what behaviour the animal was performing. By doing so, you can personally contribute essential information to the scientific community and help preserve cetacean populations!
Sources
- Baker, I., O’Brien, J., McHugh, K., & Berrow, S. (2017). An ethogram for bottlenose dolphins (Tursiops truncatus) in the Shannon Estuary, Ireland. Aquatic Mammals.
- Dudzinski, K. M., & Ribic, C. A. (2017). Pectoral fin contact as a mechanism for social bonding among dolphins. Animal Behavior and Cognition, 4(1), 30-48.
- Janik, V. M. (2015). Play in dolphins. Current Biology, 25(1), R7-R8.
- Kavanagh, A. S., Owen, K., Williamson, M. J., Blomberg, S. P., Noad, M. J., Goldizen, A. W., … & Dunlop, R. A. (2017). Evidence for the functions of surface‐active behaviors in humpback whales (Megaptera novaeangliae). Marine mammal science, 33(1), 313-334.
- Weihs, D., Fish, F. E., & Nicastro, A. J. (2007). Mechanics of remora removal by dolphin spinning. Marine mammal science, 23(3), 707-714.
- “See dolphins punt fish out of water to stun and eat them” – https://www.nationalgeographic.com/
- “Why do dolphins sometimes throw their food around?” – https://www.earthtouchnews.com/
- “Making a splash – why do cetaceans breach?” – https://www.seawatchfoundation.org.uk/
Megan
Feature Blogger
Sea Watch Volunteer
