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Seabird

life science Maturity 5-7 Next article →

Seabirds are birds that have adapted to live within the marine environment.

Wilson's storm petrel
Wilson's storm petrel

While they vary in behavior and physiology, many show convergent evolution. This means different species develop similar traits to solve the same environmental problems. For example, auks and penguins look similar because they both occupy similar feeding niches. Most seabirds follow a specific life pattern. They generally live longer and breed later than many land birds. They also have fewer young, but they invest a great deal of time into raising them. Many species live in colonies that can range from a few dozen birds to millions.

Murre colony
Murre colony

Classification of seabirds is often somewhat arbitrary. Scientists Elizabeth Shreiber and Joanna Burger noted that most seabirds share the trait of feeding in saltwater. By convention, several groups are officially classified as seabirds. These include the Sphenisciformes, which are penguins, and the Phaethontiformes, known as tropicbirds. The Procellariiformes, which include albatrosses and petrels, are also included. The Suliformes group contains gannets, boobies, frigatebirds, and cormorants. Some Charadriiformes, such as gulls, terns, and skimmers, are also considered seabirds. However, birds like loons and grebes are usually called water birds because they nest on lakes.

African Penguin Skeleton
African Penguin Skeleton

Seabirds have evolved complex biological mechanisms to survive at sea. One vital mechanism is osmoregulation, which is the process of managing salt levels in the body. Because they drink saltwater and eat salty prey like crustaceans, they ingest much salt. To manage this, they use salt glands located in their heads. These glands emerge from the nasal cavity and excrete a liquid that is almost pure sodium chloride.

Pelican in its piety
Pelican in its piety

Their plumage also serves specific functions. Most seabirds have waterproof feathers and a dense layer of down to keep out the cold. However, cormorants have unique feathers that are partly wettable. This helps them reduce buoyancy so they can dive more easily.

Phalacrocorax-auritus-007
Phalacrocorax-auritus-007

Physical adaptations are often tied to how a bird moves and feeds. Wing morphology, or the shape and size of the wings, tells scientists about a bird's lifestyle. Pelagic species, which live far out at sea, often have long wings and low wing loading. In contrast, diving species typically have shorter wings and high wing loading. The wandering albatross uses a technique called dynamic soaring. This involves using the wind deflected by ocean waves to provide lift. This allows them to forage over huge areas without using much powered flight. Many seabirds also have webbed feet to assist with movement on the water and during diving.

Seabirds have a deep history in the fossil record. They first appeared during the Cretaceous period. One early example was the Hesperornithes, which were flightless birds that could dive using their feet. They even had beaks filled with sharp teeth.

Hesperornis
Hesperornis

Other Cretaceous birds, like the Ichthyornithes, looked more like modern gulls. Modern seabird families emerged during the Paleogene. This happened after the extinction of many marine reptiles and pterosaurs. During the Miocene, many modern genera began to spread out. The highest diversity of seabirds likely occurred during the Late Miocene and the Pliocene.

Riviere au Tonnerre 033
Riviere au Tonnerre 033

Feeding strategies are divided into four main ecological guilds. These include surface feeding, pursuit diving, plunge diving, and the predation of higher vertebrates. Surface feeders can feed while flying or while swimming. Some, like storm petrels, may "walk" or patter on the water's surface to find food.

Wilson's storm petrel
Wilson's storm petrel

Others, like the skimmer, fly with their lower mandible, or bottom beak, in the water. The skimmer's lower mandible is uniquely longer than its upper one. Some birds, such as prions, have special filters called lamellae in their bills to catch plankton. Other birds use hooked bills to snatch fast-moving prey from the water.

Human activity has a significant impact on seabird populations today. Many species are currently threatened by oil spills and fishing activity. Offshore development and climate change also pose serious risks. Severe weather can further impact their survival. To help, conservation efforts have been established, such as creating wildlife refuges. People also work to adjust fishing techniques to protect these birds. Historically, seabirds and humans have shared a long connection. They have guided sailors to land and helped fishers find productive fishing stocks.

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🖼️ Images & Media (11)
File:Shark scare (535163908).jpg
Shark scare (535163908).jpg
File:Riviere au Tonnerre 033.jpg
Riviere au Tonnerre 033.jpg
File:Hesperornis.jpeg
Hesperornis.jpeg
File:Phalacrocorax-auritus-007.jpg
Phalacrocorax-auritus-007.jpg
File:Wilson's storm petrel.jpg
Wilson's storm petrel.jpg
File:African Penguin Skeleton.jpg
African Penguin Skeleton.jpg
File:Morus bassanus billing.jpg
Morus bassanus billing.jpg
File:Murre colony.jpg
Murre colony.jpg
File:Seabirds longlinersm.jpg
Seabirds longlinersm.jpg
File:Oiledcrestedauklet.jpeg
Oiledcrestedauklet.jpeg
File:Pelican in its piety.jpg
Pelican in its piety.jpg
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