An overview of social and feeding behaviour frequently seen around the Isle of Man
Head slapping thought to be a communication signal. In this encounter, one individual slapped his head a total of 11 times whilst the others swam and breached near our boat. It may also be a distraction method towards a boat, particularly if there are calves present.
Logging is a form of rest displayed by dolphins and porpoises. The animal rests just beneath the surface with only the top of the back and dorsal fin visible at the surface. This behaviour is often observed after a large feed and allows the animal to rest and conserve energy. You may see fast swimming associated with chasing prey, before a quick period of logging, then a return to foraging activity
Blowing (whale spout)
Blow occurs when a cetacean exhales, before taking a new breath, resulting in water droplets being shot up into the air. The blow-hole can empty and refill the lung in one fifth of a second. Blow is usually seen in the large whales, and each species has a different shape and size blow. Although dolphins and porpoises do produce these water droplets, they are so fine and sparse that they can only be seen if the water is very still and the weather humid.
Foraging (Suspected Feeding)
Unless a fish is actually seen being chased, we can only guess that a porpoise, dolphin or whale is foraging based on its behaviour. When foraging, the individual or group will surface frequently, changing direction all the time. A foraging group can remain in the same area for hours at a time.
Spy hopping is usually displayed in cetaceans with square heads (e.g. Risso’s dolphins, pilot whales and Orca). The behaviour enables the animal to take a look above the surface by rising vertically out of the water. It could help assess the position of other members of the pod, look for bird activity to help find food or to take a look at human activity e.g boats.
Breaching is when a cetacean leaps clear of the water. A breach may be full bodied or partial, and is considered a social, playful and communication behaviour. It may help build muscle, reinforce relationships and strengthen communication skills. It is a behaviour observed in most dolphin species, although some whales also breach; most notably the Humpback whale.
When travelling, or ‘normal swimming’, the movement of the animals will be constant, heading in a particular direction. Fast swimming can be differentiated from this by the amount of white water produced as they break through the surface. Sometimes a dolphin will swim at such a pace that their entire body leaves the water and almost skims the surface in a behaviour known as porpoising.
A young calf must surface more regularly than an adult due to their small lung capacity. You will see youngsters popping their heads up every few seconds, often pressed right beside their mother. They surface quite irrationally and almost appear to bob up and down rather than a steady swim. In some species, such as the Bottlenose dolphin, calves will stay with their mother for 2 years.
Bow-riding is a highly playful and interactive behaviour. Often a pod of dolphins will approach and swim at pace at the bow and stern of a vessel, breaching and swerving their bodies from side to side as they do so. It may help strengthen bonds within the pod and enhance muscle but is predominantly a form of play and enjoyment.
Tail slapping is used to communicate with other pod members. Risso’s dolphins often tail slap by swimming upside down, flicking the tail up and down so it crashes on the surface thus creating vibrations through the water. It can be used for many reasons but one theory is that it is used to cause distraction if disturbed by a vessel, when calves are present.
Lunge feeding and bait balls
Lunge feeding is a behaviour observed in baleen whales when feeding on a bait ball (a very tight shoal of fish forced together into a ‘ball’). The whale will accelerate from below the bait ball with its mouth open wide, the fish are forced upwards towards the surface with nowhere to go and are consumed in great quantities by the whale. Bait balls are always a great attraction for other animals too. Dolphins and sharks are among the predators joining the feast. Marine birds swarm and dive in large numbers benefiting from the fish being driven up to the surface.
All baleen whales possess hair like ‘baleen plates’ made from keratin of which hundreds are present in each jaw. When feeding the whale will take in huge quantities of water and food and use the hairy plates to filter out the good bits, dispel the water and use their tongue to swallow the food.