Monday, January 09, 2006
Flamingoes
Flamingos (genus Phoenicopterus monotypic in family Phoenicopteridae) are gregarious wading birds, usually 3–5 feet in height, found in both the Western and Eastern Hemispheres. They are more numerous in the latter, but there are four species in the Americas against two in the Old World. Flamingos live in large flocks in aquatic areas.
The larger species breed and feed in saline or brackish habitats. Nests are made of compacted mud and are in the form of a mound with a concave top, into which the single white egg is laid.
Flamingos filter-feed on shellfish and algae. Their oddly-shaped beaks are specially adapted to separate mud and silt from the food they consume, and are uniquely used upside-down. The filtering of food items is assisted by hairy structures called lamellae which line the mandibles, and the large rough-surfaced tongue. Flamingos are also noted for balancing themselves on one leg while standing and feeding.
The young hatch with white plumage, but the feathers of a flamingo in adulthood range from light pink to bright red, due to carotenoids obtained from their food supply. All flamingos have 12 black flight feathers in each wing.
Flamingos produce a “milk” like pigeon milk due to the action of a hormone called prolactin (see Columbidae). It contains more fat and less protein than the latter does, and it is produced in glands lining the whole of the upper digestive tract, not just the crop. Both parents nurse their chick, and young flamingos feed on this milk, which also contains red and white blood cells, for about two months until their bills are developed enough to filter feed.
Friday, December 16, 2005
Bald Eagle
The adult bald eagle is a striking dark brownish black bird with a white head and tail. Juvenile birds are a mottled brown with white blotches. They do not obtain the full distinctive plumage of the adults until they are four or five years old. Bills, legs, and feet are a deep yellow.
Size: Second in size only to California condors (Gymnogyps californianus) and about the same size as golden eagles (Aquila chrysaetos), bald eagles dwarf most other North American raptors. Their wingspans range from six and a half to seven and a half feet, while body length varies from about three to three and a half feet. Bald eagles weigh from six to eight pounds. Females are larger than males and have a slightly longer wingspan.
Life Span: Bald eagles have lived up to 48 years in zoos, although their life span in the wild is likely far shorter.
Distribution and Habitat: Bald eagles occur from Baja California and Florida north to Newfoundland and Alaska. Within this area, they are nearly always found near water, along rivers, lakes, or the sea coast and coastal marshes, reservoirs, and large lakes. They also pass over mountains and plains during migration. The northern and interior populations may migrate to open water in the winter months.
Bald eagles breed in much of Alaska (where they are most common), Canada, the Pacific Northwest, along the East Coast, the Mississippi River, and the Gulf Coast, around the Great Lakes, and in other areas with sufficient water and wildlife. The birds winter along the coasts and across much of the U.S. Some reach northwestern Mexico.
Near Washington, D.C., bald eagles have increased around the Chesapeake Bay and its tributaries. They nest at several sites around the Capital Beltway, and have been seen flapping over the National Zoo.
Although unique to North America, the bald eagle's closest relatives live in other parts of the world. These include the African fish-eagle (Haliaeetus vocifer) of sub-Saharan Africa and the white-tailed sea-eagle (Haliaeetus albicilla) of Eurasia.
Diet: Bald eagles are predators. They have several adaptations that fit them for that role. They have excellent eyesight and the frontal setting of their eyes gives them excellent binocular vision as well as peripheral vision.
The eagle has a strong, hooked beak with which it tears food, but it uses its powerful, taloned feet to capture prey. Bald eagles prefer fish, which they often capture by swooping down and snatching them from the water's surface. Another successful technique is to wade in the shallow water catching fish with the bill. They also take birds, especially waterfowl, and occasional mammals.
Behavior:In addition to eating other animals such as ducks, muskrats, and sometimes turtles, they eat carrion willingly, and are notorious for robbing osprey of their catches. Eagles will wait on a favorite perch for an osprey to return to its nest with a fish in its talons for its own young, then harasses the smaller raptor until it is forced to drop its prey for the eagle to retrieve.
Behavior: Bald eagles spend hours perched in trees overlooking water, their keen eyes alert for feeding opportunities. When not fishing, they sometimes steal food from ospreys, pursue injured or healthy waterfowl, or settle in for a meal of roadkill or fish chopped up in turbines at dams (including Maryland's Conowingo Dam).
Reproduction:Southern bald eagles remain on or near their breeding territory throughout the year and probably mate for life. More northern birds may migrate long distances over the winter months and it is unknown whether pairs remain together during migration. Initiation of courtship depends on the latitude. Southern birds may begin courtship and nesting activity in the late fall or early winter, while it is more common for northern birds to court and nest in the early spring. Copulation occurs on branches or other secure perches and is preceded by tail pumping and wing flapping displays by the male.
Eagles construct their nests near water in tall trees or on cliffs using large sticks. The nest is lined with twigs, grasses and other soft materials. Each year, a pair works together to build a large stick nest high in a tree or on a cliff.
Sometimes a pair reuses the same nest for years (such as a pair that nests at Great Falls, Maryland). In Florida, bald eagles nest almost year round; they begin nesting from March to May in other areas. Since these nests are used year after year, they may become very large.
Bald eagles lay two, occasionally three, eggs that are incubated by both parents, in turns for 34 to 36 days. Often only one chick survives, but if food is plentiful they may rear two or occasionally three. Young birds fledge after 12 weeks and remain with the parents for another month.
Wednesday, December 07, 2005
Macaw Parrots
Three hundred and twenty-eight different species of parrots live on the Earth. Parrots are divided into groups such as cockatoos, lories, lovebirds, macaws, and parakeets.
Parrots range in size from the pygmy of the South Pacific which is only 3½ inches long to the hyacinth macaw which is about 10 inches long. Much of its length is in its long tail. Parrots weigh from just a few ounces to 3½ pounds. Most parrots are predominantly green, especially the ones from South America. Some American parrots are mostly blue or yellow. However, parrots may have red, green, blue, purple, white, pink, brown, yellow, and even black. They have large heads and short necks. The zygodactyolus feet of the parrot have two toes that point backwards and two toes that point forward. These toes make the parrot excellent climbers.
Smaller parrots live 10 to 15 years. Larger parrots such as the macaws and cockatoos live more than 75 years. These birds reach maturity in 1 to 4 years. Wild parrots live in the forest of tropical zones including South America, Australia, and New Guinea. A few live in Africa and mainland Asia. Parrots are hole nesters. They build their nests in holes in trees, termite mounts, rock cavities, or ground tunnels. A few exceptions will build stick nests.
The thick muscular tongue helps the parrot eat fruit, seeds, buds, nectar, and pollen. Sometimes they will eat insects. Their strong beak is hooked. They feed their young by regurgitation.
Parrots have a wide range of articulations. Wild parrots do not imitate. Only pets will mimic people and noises they hear. The African gray parrots are the best mimics.
Some species of the parrot have become endangered. Thousands are brought to Europe and North America as pets. Many of these die making this journey
