Orcas (or killer whales) are actually part of the dolphin family. They have jet-black, brilliant white and grey markings making them quite distinctive. They have a white belly, a large white patch on the side of the head and a grey saddle patch. The adult male’s dorsal fin is huge at up to 1.8 metres making them easy to identify. Females and young males however can sometimes be mistaken for Risso’s dolphins, False Killer whales or Dall’s porpoise from a distance.
These animals are very intelligent and because of this can be very inquisitive and approachable. However, they rarely bow-ride but instead can often be seen breaching, spy-hopping (just the nose coming out of the water), flipper splashing and lobtailing (slapping their tail-fin down on the water). Powerful swimmers, they can reach speeds of 55km per hour. In the Hebrides, killer whales are known to spend a whole day with a boat, delighting the passengers. Despite the name “killer whale” they do not harm humans in the wild and agression within a pod is rare. The life span of a wild orca is up to 60 years for males and 90 years for females – this is drastically reduced in captivity.
Orcas are one of the most wide-ranging mammals on earth. They are seen more often in cooler waters, especially polar regions. They are usually found within at least 500 miles of the shore. They tend to prefer deep water but can be found in shallow bays and estuaries. Orcas are occasionally sighted in the Hebrides – sightings hotspots are the Isles of Coll and Tiree, west of Canna, the East coast of Lewis and the Sound of Harris. Many reported sightings appear to be of the same pod of about 8 animals. Adults can be individually identified by the distinctive nicks and markings on their dorsal fins.
An opportunistic and voracious feeder, the orca is one of the ocean’s top predators, with a varied diet of fish, octopus and squid, as well as birds, seals and other cetaceans. In the Hebrides orcas have occasionally been spotted chasing and taking seal pups from beaches. They often hunt co-operatively, especially when pursuing marine mammal prey.
Orcas have been hunted in the past for commercial whaling, and are still captured for public dislay in oceanaria, although this is illegal in the United Kingdom. At the top of the food chain, they have no natural predators, and are at risk only from man’s activities.