ClimateWatch

An initiative of Earthwatch Institute

  1. 237 Photo by David Donnelly
  2. 237_0 Photo by David Donnelly

Orca (Killer whale)

Orcinus orca

Appearance

  • Orcas are the largest member of the dolphin family
  • Colour: Mostly black in colour with a light grey saddle behind the dorsal fin and a distinct white oval shaped horizontal patch behind the eye. The belly, underside of the jaw and underside of the tail are also white
  • Appearance: Mature males have a tall triangular shaped dorsal fin that may reach up to 1.8 metres in height. Females and juveniles have a smaller, more curved dorsal fin
  • Size: Adult orcas can grown to a length of 10 m

Behaviour

Orcas can be found feeding, travelling, resting or socialising in Australian waters. However they are rarely seen at the surface for long periods making them difficult to spot. Occasionally they may hold their head out of the water, known as ‘spy hopping’ which may help them to see their surroundings. They prey on whales and dolphins as well as fish and are known to “play” with their food.

 

What to Observe

  • How many adults and calves
  • Behaviour: stationary, milling (lazing around), feeding, active (describe in the comments if the whale was jumping, rolling or waving its fins), travelling (and travel direction)
  • Distance from shore (Hint: If you're unsure use a nearby buoy or other feature of know distance from shore)
  • Weather and sea state (cloud cover, wind and swell)
  •  Photograph of dorsal fin (photo tip: Adult male orcas can be identified by the unique shape and scarring on their dorsal fin. Photos should be taken when standing perpendicular to the orca and of both sides of the dorsal fin . Photos should be taken of all whales sighted and having your camera set to ‘continuous shooting mode’ will ensure the best possible chance of clear identification from photos)

ClimateWatch Science Advisor

Orcas are top predators, with their movements and behaviours  shaped according to the seasonal movements and availability of their prey. Warmer ocean waters and currents will change the distribution of small fish and invertebrates that occupy the bottom of the food chain, and in turn, alter the distribution of larger marine species such as seals, penguins and whales. Orcas will respond to the changes in the bottom of the food chain by changing where they feed and what they feed on. We expect orcas to alter their diet and feeding locations in response to changes in the distribution of prey.

When To Look

Orcas are sighted sporadically all around Australia at different times of year. They focus their feeding activities on the southern shorelines near seal colonies during spring and along whale migration routes during winter. Repeated annual sightings of orcas at Eden, NSW, on the east coast (October) and Exmouth, WA, on the west coast (July) coincide with the humpback whale migration where the orcas are looking for calves that might become separated from their mothers.  ‘Australian’ orcas are currently poorly understood. There is evidence of medium range migration that shows some correlation with the migration and breeding of target prey species such as fur seals and humpback whales. Orcas from other parts of the world are known to make seasonal movements and ‘Australian’ orcas may possibly migrate between Antarctic and mainland Australia, following the seasonal migration of their prey. Their location might be revealed by the presence of birds attracted to the pod during times of hunting.

Where To Look

Orcas are found all around the world in most major oceans and seas with occasional forays into rivers. They are particularly common in colder waters like Antarctica, and the Arctic.

Orca Occurrence Map ALA

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  1. What Else?

    Orcas are unmistakable, their large size and distinctive features make them easily identifiable.  

  1. Did You Know?

    During the times of commercial whaling off Eden, NSW, resident orcas would help whalers round up baleen whales in Twofold bay. As a reward, the orcas would receive the lips and tongue of the catch. This cooperative relationship endured over many decades.