Bec Wellard listening to orcas – music to her ears!
No write-up can capture the exuberance of the multi-media presentation given by Project ORCA (Orca Research & Conservation Australia) member and Curtin PhD candidate, Bec Wellard. Her talk on Killer Whales (Orcinus orca), originally known as whale killers apparently, was accompanied by superb photos, videos taken both above and below the surface and hydrophone recordings—some of which had not been heard by the public before.
Some things we learnt at the beginning:
- Killer Whales, the largest member of the dolphin family, are found worldwide, being the most widespread mammal after humans.
- Killer Whales show sexual size dimorphism—adult males grow to 10m and can weigh up to 10,000kg while females reach only 8.5m and 7 500kg. Calves are 2.5m when born and weigh around 180kg.
- Adult males can be distinguished by their large, tall triangular dorsal fin, whereas adult females and sub-adult males have a more curved and falcate dorsal fin.
- Killer Whales are highly intelligent, live in complex societies, have strong family bonds and stay in tight-knit matrilineal groups led by older females that model specific behaviours to younger animals.
- Each population has its own language, dialect, social structure, food preference and hunting behaviours—essentially its own culture—which is passed on from the older generations to the younger ones the same way it is in humans. They teach them what to eat and where to find it, how to catch it, who to avoid, vocalizations/calls unique their family group, and the “accent” of their population.
- Killer Whales have been recorded off the coast of all the Australian states and territories with three aggregation areas having been recognised, Ningaloo, Bremer Canyon and Eastern Tasmania.
- The Ningaloo population is known for its predatory habits—feeding on humpback whale calves in particular during the migratory season (September-October) and dolphins during other times.
- The Bremer Canyon has a large variety of animals (Pilot Whales, Beaked Whales, Sperm Whales, Bottlenose, Common and Striped Dolphins, False Killer Whales, pinnipeds, seabirds, pelagic sharks, sunfish) in addition to the killer whale population, which only inhabits the area between January and April. Their whereabouts for the other eight months is unknown.
Genetic analysis of the Killer Whales’ DNA is quite complex and geneticists are still in discussion on where the different populations of orca worldwide fit in the taxonomy. For now, killer whales are all considered one species. However, where they have been studied in detail e.g. the North Pacific, North Atlantic and Antarctica, they can be divided into ‘ecotypes’ based on their geographic distribution and feeding habits. No ecotype is defined for Killer Whales in Australian waters due to the lack of information.
Bec, who is now into the final year of her five year project, is the first person to study Killer Whales in Australia for a PhD thesis. Her research is directed towards non-invasive techniques such as photo-identification (Photo ID) and passive acoustic monitoring (PAM).
Each animal within a population is unique and has certain physical characteristics and distinctive markings which distinguish it from other individuals. Photo ID can be used to determine things such as calving rates, population estimates, social structure, habitat preferences and range or possible migration routes.
Cookie and big male El Notcho, two of the well-known orcas in Bremer Canyon
PAM is a non-lethal, non-invasive method for assessing Killer Whale abundance and trends, defining habitat use and monitoring population characteristics. Bec will be comparing recordings from worldwide populations to investigate whether Australia’s populations have a distinct repertoire—speaking ‘Aussie slang’!
Bec played some recent recordings of various cetaceans so we could hear the differences between:
- Echolocation—navigating and searching for prey (Sperm Whale clicks)
- Communication—group cohesion; mum-calf, feeding, etc.
- Mating call—Humpback song.
In conclusion, Bec invited everyone to become active in Project ORCA’s Citizen Science project by reporting any sightings and sending photographs and videos of these apex predators to: Project Orca email. Further information can be found at Project Orca website Project ORCA’s Facebook page has many of the photos and videos shown by Bec—highly recommended viewing and reading.