Study of Common Birds

Study of Common Birds Birds make up the scientific class Aves. They The y are warm-blooded, egg-laying vertebrate animals that are covered with feathers and possess forelimbs that have modified to become wings. Birds also have scaly legs, and no teeth (except in a few early ear ly fossil forms). They maintain a constant body temperature of about 41 degrees de grees C (106 degrees F). All birds today have descended from their flying ancestors, but a few such as ostriches, emus, some grebes, and cormorants corm orants have lost their capacity for aerial flight. Others, such as penguins, have become adapted to flying in a much denser medium, water. Birds are found in all habitats, from the icy shores shor es of Antarctica to the hottest parts of the tropics, and from mountains, deserts, plains, and forests to open oceans and densely urbanized areas. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from the 5 cm (2 in) Bee Hummingbird to the 2.75 m (9 ft) Ostrich. The fossil record indicates that birds evolved from theropod dinosaurs during the Jurassic period, around 150–200 Ma (million years ago), and the earliest known bird is the Late Jurassic Archaeopteryx, c 150–145 Ma. Most paleontologists regard birds as the only clade of  dinosaurs to have survived the Cretaceous–Tertiary extinction event approximately 65.5 Ma. Modern birds are characterized by feathers, a beak with no teeth, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a lightweight but strong skeleton. All living species of birds have wings - the now extinct flightless Moa of New N ew Zealand were the only exceptions. Wings are evolved forelimbs, and most bird species can fly, with some exceptions including ratites, penguins, and a number of diverse endemic island species. Birds also have unique digestive and respiratory systems that are highly adapted for flight. Some birds, especially corvids and parrots, are among the most intelligent animal species; a number of bird species have been observed manufacturing and using tools, and an d many social species exhibit cultural transmission of knowledge across generations. Many species undertake long distance annual migrations, and many more perform shorter irregular movements. Birds are social; they communicate using visual signals and through calls and songs, and participate in social behaviors including cooperative breeding and hunting, flocking, and mobbing of predators. The vast majority of bird species are socially monogamous, usually for one breeding season at a time, sometimes for years, but rarely for life. Other species have breeding systems that are polygamous ("many females") or, rarely, polyandrous ("many males"). Eggs are usually u sually laid in a nest and incubated by the parents. Most birds have an extended period of parental care after hatching. Many species are of economic importance, mostly as sources of food acquired through hunting or farming. Some species, particularly songbirds and parrots, are popular as pets. Other uses include the harvesting of guano (droppings) for use as a fertilizer. Birds figure prominently in all aspects of human culture from religion to poetry to t o popular music. About 120–130 species have become extinct as a result of human activity since the 17th century, and hundreds more before then. Currently about 1,200 species of birds are threatened with extinction by human activities, though efforts are underway to protect them.

Blue Jay

The Blue Jay is a common, large songbird is familiar to many people, with its perky crest; blue, white, and black plumage; and noisy calls. Blue Jays are known for their intelligence and complex social systems with tight family bonds. Their fondness for acorns is credited with helping spread oak trees after the last glacial period. Blue jays can make a large variety of sounds, and individuals may vary perceptibly in their calling style. Like other corvids, they may learn to mimic human speech. spe ech. Blue jays can also copy the cries of local hawks so well that it is sometimes difficult to tell which it is.[4] Their voice is typical of most jays in being varied, but the most commonly recognized sound is the alarm call, which is a loud, almost gull-like scream. There is also a high-pitched jayer-jayer call that increases in speed as the bird becomes more agitated. This particular call can be easily confused with the chickadee's song because of the slow starting chick-ah-dee-ee. Blue  jays will use these calls to band together to mob potential predators such as hawks and drive them away from the jays' nests. Blue jays also have quiet, almost subliminal calls which they use among themselves in proximity. One of the most distinctive calls of this th is type is often referred to as the "rusty pump" owing to its squeaky resemblance to the sound of an old hand-operated water pump. The blue jay (and other corvids) are distinct from all other songbirds for using their call as a birdsong.

Song Sparrow

Aptly named, the Song Sparrow will sing as many as 20 different melodies with as many as 1,000 improvised variations on his basic theme. In areas where the birds migrate, the male arrives on the breeding ground ahead of the female and starts to define a territory by singing his song from three or four prominent perches. The Song Sparrow is 5 to 6 inches in length, heavily streaked gray-brown upperparts. Dull Du ll white underparts have dark central breast spot, thick t hick streaks. Head has brown crown, paler median stripe, pale gray eyebrow, white chin, dark brown moustache stripe. Rust-brown wings. Tail is long, usually tinged rust-brown. Birds in some areas will vary, with paler subspecies in the Southwest and darker subspecies along the West Coast. In early spring the male sings constantly and defends his territory. territory . When the female first arrives, the male will dive at her as he does with any other intruder, but the female does not flee. In time the male will accept this behavior and the two will begin to move about the territory together. At this stage the male will reduce his singing to only about ten Songs per hour. Once the nest building has started, the male Song Sparrow will renew his singing. The nest is cup-shaped and made of grasses and occasionally leaves, placed on the ground early in the year, and up to 30 feet above the ground later in the season. Although the male may carry nesting materials, it's the female who builds the nest. The female lays one egg each day until the clutch of 3 to 5 greenish green ish white with dark marks is complete.

Bald Eagle

The bald eagle, with its snowy-feathered (not bald) head and white tail, is the proud national bird symbol of the United States—yet the bird was nearly wiped out there. For many decades, bald eagles were hunted for sport and for the "protection" of fishing grounds. gr ounds. Pesticides like DDT also wreaked havoc on eagles and other birds. These chemicals collect in fish, which make up most of the eagle's diet. They weaken the bird's eggshells egg shells and severely limited their ability to reproduce. Since DDT use was heavily restricted in 1972, eagle numbers have rebounded significantly and have been aided by reintroduction programs. These powerful birds of prey use their talons to fish, but they get many of their meals by scavenging carrion or stealing the kills of other animals. (Such thievery famously prompted Ben Franklin to argue against the bird's nomination as the United State's national symbol.) They live near water and favor coasts and lakes where fish are plentiful, though they will also snare and eat small mammals. Bald eagles are believed to mate for life. A pair constructs an enormous stick nest—one of  the bird-world's biggest—high above the ground and tends to a pair of eggs each year. Immature eagles are dark, and until they are about five years old, they lack the distinctive white markings that make their parents so easy to identify. Young eagles roam great distances. Florida birds have been spotted in Michigan, and California eagles have traveled all the way to Alaska.

Peacock

Peacocks are large, colorful pheasants (typically blue and green) known for their iridescent tails. These tail feathers, or coverts, spread out in a distinctive train that is more than 60 percent of the bird’s total body length and boast colorful "eye" markings of blue, gold, red, and other hues. The large train is used in mating rituals and courtship displays. It can be arched into a magnificent fan that reaches across the bird's back and touches the ground on either side. Females are believed to choose their mates according to the size, color, and quality of these outrageous feather trains. The term "peacock" is commonly used to refer to birds of both sexes. Technically, only males are peacocks. Females are peahens, and together, they are called peafowl. Suitable males may gather harems of several females, each of which will lay three to five eggs. In fact, wild peafowl often roost in forest trees and gather in groups called parties. Peacocks are ground-feeders that eat insects, plants, and small creatures. There are two familiar peacock species. The blue peacock lives in India and Sri Lanka, while the green peacock is found in Java and Myanmar (Burma). Peafowl such as the blue peacock have been admired by humans and kept as pets for thousands of years. Selective breeding has created some unusual color combinations, but wild birds are themselves bursting with vibrant hues. They can be testy and do not mix well with other domestic birds.