Shearwater

Puffinus gravisPCCA20070623-3738B

Shearwater refers to a group of seabirds that belong to the family Procellariidae, which also includes petrels and fulmars. Shearwaters are highly adapted to life at sea, with species distributed across all the world's oceans. They are known for their long, slender wings, which allow them to glide effortlessly over the water's surface, and for their exceptional diving capabilities, used to catch fish and squid.

Description

Shearwaters are medium-sized birds, with body lengths ranging from 30 to 55 cm. They have a streamlined body shape, with long, narrow wings and a slightly hooked bill. Their plumage is typically dark on the upperparts and lighter on the underparts, providing camouflage against predators from both above and below while flying or floating on the water. Shearwaters are also noted for their strong, musky odor, a characteristic derived from the oils and stomach contents they regurgitate as a defense mechanism.

Habitat and Distribution

Shearwaters are pelagic birds, spending the majority of their lives far out at sea, only coming ashore to breed. They can be found in a wide range of oceanic environments, from the cold waters of the North Atlantic to the warmer regions of the Pacific and Indian Oceans. Some species, such as the Sooty Shearwater, undertake long-distance migrations, traveling thousands of kilometers between their breeding and feeding grounds.

Behavior

Shearwaters are social birds, often seen in large flocks, especially during migration. They are excellent fliers, capable of using dynamic soaring and slope soaring to travel over the ocean with minimal energy expenditure. Shearwaters are also proficient divers, using their wings to propel themselves underwater in pursuit of prey.

Feeding

The diet of shearwaters primarily consists of fish, squid, and crustaceans. They employ various feeding strategies, including surface seizing, diving from the air, and pursuit plunging, to capture their prey. Some species are known to follow fishing boats to feed on offal and discarded fish.

Breeding

Shearwaters are colonial nesters, with some colonies located on remote islands numbering in the millions of individuals. They nest in burrows or crevices, laying a single white egg per breeding season. Both parents share incubation duties and take turns feeding the chick after it hatches. The breeding cycle of shearwaters is long, with chicks taking several months to fledge.

Conservation

Many shearwater species are facing threats from human activities, including habitat destruction, pollution, and the introduction of invasive species to their breeding islands. Some species are also affected by bycatch in commercial fisheries. Conservation efforts are underway in several regions to protect these birds, including habitat restoration, predator control programs, and the implementation of bycatch mitigation measures in fisheries.