These beautiful creatures have slowly, over millions of years, adapted to life in a particularly harsh environment, the ocean. The sea covers about 70% of the Earth's surface, yet seabirds comprise only 3.8% of the world's bird species. Once they evolved to overcome the many obstacles that being largely or wholly dependent on the marine environment entailed, however, they were without much competition, so many of these species are extremely numerous.
These adaptations include the evolution of salt glands, which help to render these birds very independent of land because they no longer need fresh water to drink. Many other changes were needed to embrace a life of swimming and diving, such as modifications to the hind limbs, enhanced waterproofing of feathers and increased insulation.
The size, shape and structure of seabirds varies enormously: while albatrosses possess the longest wings of any bird in the world, penguins are flightless and have wings reduced to flippers. Storm petrels may weigh as little as 25 grams, while the royal albatross can weigh up to 12kg!
These birds have also developed several different feeding strategies in order to exploit the varied riches of the marine environment.
The Galapagos seabird population is made up of four of the seven existing orders (five if you count our resident duck, Anas bahamensis, which, however, is not a marine species of its family). The boobies, cormorant, frigates, tropicbird and pelicans belong to the Order Pelecaniformes; the gulls and terns to the Charadriiformes, the albatross, shearwater and petrels to the Proscellariiformes; and finally the only representative of the Sphenisciformes: our Galapagos penguin (Spheniscus galapaguensis).
We have 19 resident seabird species, of which five are endemic to the islands: the beautiful waved albatross; both of the resident gull species, the flightless cormorant and our unique pioneering penguin (in the picture). Though this makes up over 26% of the total population, it is nowhere near the rate of endemism in Galapagos land birds, which is 85%! This is because seabirds are often built to fly (or swim) enormous distances, thus crossing the ocean barrier and lessening the isolation that is a vital part of the formation of new species.
