(verb) The act of leaping in and out of the water in a short, shallow arc while swimming. Penguins are well known for porpoising, and other swimming seabirds such as murres and auks also practice porpoising while in the water, but to a lesser extent.
This type of swimming is less energy efficient than staying completely submerged, but it has the benefit of allowing the birds to breathe more regularly. It is also believed that deliberate porpoising may be used to confuse and disorient both predators and prey, and some observations have shown that birds may porpoise simply out of joy or excitement.
The length of the porpoising leap can vary from 2-6 feet (.6-1.8 meters) depending on the water conditions, bird size and swimming speed. Penguins are equipped with powerful flippers that help them porpoise more easily and for greater distances. The angle of the leap is generally shallow and allows the bird to cover more distance in the air. Birds that porpoise have streamlined bodies that allow them to break the surface of the water easily on these types of leaps without risking injury.
Photo – Gentoo Penguins Porpoising © Gilad Rom