Seabird

Seabirds (also known as marine birds) are birds that are adapted to life within the marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent evolution, as the same environmental problems and feeding niches have resulted in similar adaptations. The first seabirds evolved in the Cretaceous period, while modern seabird families emerged in the Paleogene. Seabirds generally live longer, breed later and have fewer young than many other birds, but they invest a great deal of time in their young. Most species nest in colonies, varying in size from a few dozen birds to millions. Many species are famous for undertaking long annual migrations, crossing the equator or circumnavigating the Earth in some cases. They feed both at the ocean's surface and below it, and even on each other. Seabirds can be highly pelagic, coastal, or in some cases spend a part of the year away from the sea entirely. Seabirds and humans have a long history together: They have provided food to hunters, guided fishers to fishing stocks, and led sailors to land. Many species are currently threatened by human activities such as oil spills, fishing activity, offshore development, climate change and severe weather. Conservation efforts include the establishment of wildlife refuges and adjustments to fishing techniques.