Researchers have identified four basic behaviors that are exhibited by orcas; foraging, resting, traveling and socializing. However, so much of orca life is hidden beneath the water that it is extremely difficult to label all activities. Orcas in British Columbia spend a great deal of time at a particular beach where they rub their bodies on smooth round pebbles at the bottom of the cove. No one really knows what purpose this activity serves, yet the whales are extremely secretive here and will stop if they are interrupted by humans. Happily, this area, Robson Bight, has been declared an ecological preserve that is off limits to boats and hikers.
Foraging is defined as any activity associated with feeding or searching for food and is understandably the most common orca behavior. Resident pods in the Pacific Northwest spend on average 65% of their time foraging, yet they can spend as little as two to three hours when fish are plentiful. Obviously, declines in fish stocks and the disruptive influence of boat traffic force these whales to spend proportionately more time in foraging mode. This reduces time spent resting or socializing and may account for the higher mortality rates seen over the last four years.
Resting behavior is characterized by a series of highly regular shallow dives performed in unison with other pod members at very slow speeds (1 to 2 knots). Resting is unlike human sleep due to the Orca's need to maintain conscious control over breathing. Resting behavior often follows a period of foraging and usually lasts a couple of hours. During resting, whales lie tightly together with all offspring clustering around their mother, youngest closest. Resting accounts for 13% of resident orcas' observed activity.
Traveling is defined as swimming in one direction, at a fast to moderate pace (5 knots), in tight formation with no sign of feeding. During this time orcas are extremely vocal and will surface and dive in unison. In fact they are often seen completely clearing the surface of the water as they breathe. Traveling behavior is less common in the narrower ranging resident pods than it is among transients, since it is usually associated with movement from one feeding ground to another.
