Seabirds are birds that have adapted to live in or near a saltwater environment.
While they range in size, lifestyle, and even general appearance, all seabirds depend upon the ocean or sea for part or all of their livelihood.
The most well-known types include penguins, gulls, auks, pelicans, and albatrosses.
Physical Characteristics
Because each species evolved to survive in its own unique environment, seabirds exhibit a wide range of physical characteristics.
The ten foot wingspan of a Wandering Albatross, for example, bears little resemblance to the short, flightless wings of a Rockhopper Penguin.
In spite of such differences, however, most seabirds do have several physical traits in common, including:
• Webbed feet, which improve mobility both on land and in the water
• Salt glands, which handle the saltwater that seabirds often consume while feeding or drinking
• Dense, waterproof plumage, which facilitates life in a marine environment
• Subdued colors, typically focused on black, white, or gray, which act as natural camouflage when on the sea
Diet
The majority of seabirds base their diet upon marine life, and many, such as albatrosses, often fly great distances to obtain a meal.
Common sources of food for seabirds include:
• Fish
• Squid
• Crustaceans
• Krill
• Plankton
Some birds, such as frigatebirds and gulls, will also engage in scavenging or stealing food.
In some cases, they will even feed upon other seabird species’ eggs, chicks, or nesting adults.
Social Structure
Seabirds typically wait longer than other types of birds do to have offspring.
In addition, they produce fewer chicks at a time, sometimes laying as little as one egg a year.
Once chicks hatch, however, both parents tend to devote a large amount of time to care for their young, sometimes flying with them for months over the sea.
These parents are almost always monogamous for at least one season, and some petrel and albatross species form pair bonds that last for life.
Breeding
The overwhelming majority of seabirds form nesting colonies, with many of the members returning for breeding to the same area in which they themselves were hatched.
Since most seabirds are migratory and may travel long distances, their ability to remember and return to a specific birthplace is remarkable.
While colonies often contain only members of one species, it is not uncommon for several different types of seabirds to share one area for nesting.
In these cases, the more aggressive species tend to take the most desirable locations, leaving less aggressive species to form their own groups in less coveted parts of the area.
Habitat
Seabirds typically live near saltwater, although the amount of time they spend there is highly variable.
Some seabirds spend most of their lives inland, while albatrosses may remain on or over the ocean for several years.
Most, however, live close enough to saltwater that they can easily feed on fish and other sea life.
Seabirds exist near oceans and seas all over the world, from the Emperor Penguin in Antarctica to the Brown Booby in the tropics.
In addition, many seabirds migrate thousands of miles a year, crossing the equator and, in some cases, circling the globe.
Any area with saltwater will likely be a habitat for some type of seabird.
Threats
The greatest threats to seabirds are:
• Overhunting by humans for feathers, eggs, and other products, which caused the extinction of such species as the Great Auk
• Introduction by humans of predators into previously safe nesting areas
• Destruction of seabird habitats by factors like oil leaks and pollution
• Ecologically disruptive activities, such as overfishing
• Longline fishing, which, when performed without safety streamers, hooks and drowns tens of thousands of albatrosses and other seabirds each year.
Seabirds have been a vital, beautiful part of the Earth’s ecosystem since the Cretaceous Period, but ensuring that they remain so requires our care and attention.