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Marine Birds. Why Fly? What is a Marine Bird? Seabird Habitats. What is a bird? Why fly?. There are 9,700 species of birds which are the most numerous terrestrial vertebrate class. Except for bats and prehistoric reptiles, birds are the only vertebrates that fly.
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Marine Birds Why Fly? What is a Marine Bird? Seabird Habitats
What is a bird? Why fly? • There are 9,700 species of birds which are the most numerous terrestrial vertebrate class. • Except for bats and prehistoric reptiles, birds are the only vertebrates that fly. • Birds have scales on their legs and beak. Feathers are highly modified versions of the reptilian scales. • All body changes between reptiles and birds appear to be related to the ability to fly. The two requirements: • More power • Less weight
Characteristics of Birds • Endothermic (warm blooded) • Covered in feathers • Light-weight bones • There are many benefits to flying: • Can gain access to food that is in the air; or can be seen in the air. • Can escape from non-flying predators. • Can search for food and shelter quickly • Can travel according to season, moving to where conditions are more favorable. • Can spread over distances and barriers that would be insurmountable.
What is a Marine bird? • The term “marine birds” includes both seabirds and shorebirds. These groups make up about 6% of the 9,700 bird species distributed worldwide. • Monterey Bay has about 130 species – some residents and others migrants. • For true seabirds, the sea is the primary habitat and source of food. These birds include albatrosses, shearwaters, petrels, pelicans, cormorants, gulls, terns, murres, guillemots, and phalaropes. • Some birds live in freshwater habitats while breeding, but they may migrate to and overwinter in coastal area. These birds include loons, grebes, and sea ducks.
Shorebirds are those species which feed (at least in the winter) along coastal beaches, mudflats or rocky shores. This group includes members of the sandpiper, plover, avocet, oystercatcher and phalarope. • Some members of the heron and egret family frequent the shore, but are not true shorebirds.
Specialized Feeding Adaptations • Seabirds that swim and dive have long, cylindrical bodies with the center of gravity and legs that are near the rear. Some can use their wings to “fly” under water. • Most have water-repellent plumage. They have relatively solid bones and heavy bodies to overcome buoyancy. • Most diving species are dark above and white below (like countershading in fishes). • Many seabirds make long migrations. They have very long wingspans for soaring. • Ocean birds can drink sea water. They have special salt or nasal glands located between the eyes and beak. • Some seabirds have a keen sense of smell which they use together with sight to find prey, nesting sites, and mates.
Seabird Habitats • Open Ocean: The open ocean (the ocean beyond the continental shelf) is inhabited by pelagic birds that don’t come ashore to rest or feed, except during the breeding season. Truly pelagic birds remain far out to sea night and day. They rest and sleep on the sea surface, drink sea water and feed on animals of the open sea. • Nearshore Waters and Bays: These species are called “inshore” or “coastal” seabirds because they usually stay shoreward of the 164 feet line. Pelicans, cormorants and some gulls return to land at night to roost. • Most seabirds in Monterey Bay are visitors. Only 13 species are residents known to breed on or near Santa Cruz and Monterey counties.
A major problem for most seabirds during breeding season is that they can’t breed on their feeding grounds; they need islands or other safe, suitable breeding areas. During the breeding season seabirds can spend a lot of time commuting to and from feeding areas. • The great distances between breeding and feeding areas, together with patchy distribution of food, make it difficult for seabirds to feed a large number of chicks. As a result, the number of eggs the female lays is small compared to land birds. Many seabirds raise only one chick each year. • Seabird adults generally care for their young longer than do similar-sized land birds. Some seabird adults care for their young for several months. Generally the adults take turns making the trips to find food for their young.
