Be it on shore, via liveaboard or day boat, most divers will see seabirds on dive trips. These creatures are fascinating for many reasons, whether for the length of their migration or the sheer numbers in a particular colony. Here are several of the most common species to help you practice seabird identification on your next dive.
The largest, and perhaps most famous of all seabirds, the albatross was immortalized in Samuel Coleridge’s “The Rime of the Ancient Mariner.” There are 22 species of albatross, but the wandering albatross — also called the snowy albatross — is the largest of all. An adult male can reach 4.5 feet (1.4 m) in length and weigh up to 28 pounds (12.7 kg). The wandering albatross also has the longest wingspan of any living bird, ranging from eight to 11 feet (2.5 to 3.5 m). Because of its remarkable wingspan, an albatross can remain aloft for several hours without flapping its wings. Residents of the Southern Ocean, these birds feed on squid, krill and smaller fish. Because they feed at the surface, albatross populations are at risk due to bycatch from long-line fishing.
Unlike the albatross, the frigatebird inhabits primarily tropical oceans. Both sexes are extremely easy to identify. Both have distinctive long forked tails, and the male has a large, red gular pouch that protrudes from its neck to attract females during breeding season. With a wingspan of 7.5 feet (2.3 m), it has the largest wing-to-body ratio of any bird. Frigatebirds have an extremely long gestation period, and only lay one egg every two years. Known to soar for weeks at a time on the tropical winds, these birds spend most of their time searching for food, which comes in the form of small fish, squid and occasionally chicks from other species of birds.
With more than 30 species of shearwaters, it is often difficult to identify specific species. Shearwaters fly with stiff wings and use a “shearing” flight technique, wherein they fly very close to the water and seem to cut or “shear” the tops of waves with very little active flight. During breeding season, these birds spend time on islands and coastal cliffs, but become pelagic during other times of the year. Many shearwaters are long-distance migrators, particularly sooty shearwaters, which migrate over 8,700 miles (14,000 km) annually. One study found sooty shearwaters migrating nearly 40,000 miles (64,000 km) in one year.
Shearwaters feed on fish, squid and other smaller scraps and they can dive underwater as far as 200 feet (60 m).
A sleek and powerful bird, the gannet is an excellent diver. These large white birds have yellowish heads and black-tipped wings. They inhabit the North Atlantic and the southern temperate oceans, where they feed on fish by diving to depths of 100 feet (30 m) from great height at speeds up to 60 miles an hour (100 km per hour), pursuing their prey underwater. Gannets have several adaptations to help them survive these dives. For example, they do not have external nostrils; they are located inside their mouth instead. They also have air sacs in the face and chest to cushion the blow of impact with the water.
Despite not technically being a seabird, the penguin spends half of its life on land and half in the ocean. Penguins live predominantly in the southern hemisphere although one species, the Galapagos penguin, lives north of the equator. They have webbed feet, waterproof plumage and strong flippers instead of wings to help thrust themselves through the water at great speeds to catch fish, squid and krill. Penguins have one breeding partner for their entire lives, and take turns guarding their nest while the other searches for food. You can see huge colonies of penguins in the sub-Antarctic and Antarctic.