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Brief Summary

    Bird: Brief Summary
    provided by wikipedia
    For other uses, see Bird (disambiguation) and Birds (disambiguation).

    Warm-blooded, egg-laying vertebrates with wings, feathers and beaks "Aves" and "Avifauna" redirect here. For other uses, see Aves (disambiguation) and Avifauna (disambiguation).

    Birds, also known as Aves, are a group of endothermic vertebrates, characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweight skeleton. Birds live worldwide and range in size from the 5 cm (2 in) bee hummingbird to the 2.75 m (9 ft) ostrich. They rank as the world's most numerically-successful class of tetrapods, with approximately ten thousand living species, more than half of these being passerines, sometimes known as perching birds. Birds have wings which are more or less developed depending on the species; the only known groups without wings are the extinct moa and elephant birds. Wings, which evolved from forelimbs, gave birds the ability to fly, although further evolution has led to the loss of flight in flightless birds, including ratites, penguins, and diverse endemic island species of birds. The digestive and respiratory systems of birds are also uniquely adapted for flight. Some bird species of aquatic environments, particularly seabirds and some waterbirds, have further evolved for swimming.

    Reverse genetic engineering and the fossil record both demonstrate that birds are modern feathered dinosaurs, having evolved from earlier feathered dinosaurs within the theropod group, which are traditionally placed within the saurischian dinosaurs. The closest living relatives of birds are the crocodilians. Primitive bird-like dinosaurs that lie outside class Aves proper, in the broader group Avialae, have been found dating back to the mid-Jurassic period, around 170 million years ago. Many of these early "stem-birds", such as Archaeopteryx, were not yet capable of fully powered flight, and many retained primitive characteristics like toothy jaws in place of beaks, and long bony tails. DNA-based evidence finds that birds diversified dramatically around the time of the Cretaceous–Palaeogene extinction event 66 million years ago, which killed off the pterosaurs and all the non-avian dinosaur lineages. But birds, especially those in the southern continents, survived this event and then migrated to other parts of the world while diversifying during periods of global cooling. This makes them the sole surviving dinosaurs according to cladistics.

    Some birds, especially corvids and parrots, are among the most intelligent animals; several bird species make and use tools, and many social species pass on knowledge across generations, which is considered a form of culture. Many species annually migrate great distances. Birds are social, communicating with visual signals, calls, and bird songs, and participating in such social behaviours as cooperative breeding and hunting, flocking, and mobbing of predators. The vast majority of bird species are socially monogamous (referring to social living arrangement, distinct from genetic monogamy), usually for one breeding season at a time, sometimes for years, but rarely for life. Other species have breeding systems that are polygynous (arrangement of one male with many females) or, rarely, polyandrous (arrangement of one female with many males). Birds produce offspring by laying eggs which are fertilised through sexual reproduction. They are usually laid in a nest and incubated by the parents. Most birds have an extended period of parental care after hatching. Some birds, such as hens, lay eggs even when not fertilised, though unfertilised eggs do not produce offspring.

    Many species of birds are economically important as food for human consumption and raw material in manufacturing, with domesticated and undomesticated birds (poultry and game) being important sources of eggs, meat, and feathers. Songbirds, parrots, and other species are popular as pets. Guano (bird excrement) is harvested for use as a fertiliser. Birds prominently figure throughout human culture. About 120–130 species have become extinct due to human activity since the 17th century, and hundreds more before then. Human activity threatens about 1,200 bird species with extinction, though efforts are underway to protect them. Recreational birdwatching is an important part of the ecotourism industry.

    Introduction to the Birds
    provided by EOL authors
    With approximately 10,000 living species, the Aves (birds) are the only living animals with feathers. The living birds range in size from the tiny Bee Hummingibird of Cuba (about 5 cm long, 1.8 g) to the Ostrich of Africa (up to about 2.7 m tall, 256 kg). The birds are the living descendents of dinosaurs and in pure taxonomic terms they are truly living dinosaurs. They are present on all continents and most islands (probably all islands if brief visits are included). Birds live in most environments from the driest deserts to marine environments. Some species are able to dive quite deeply while some have been seen flying at over about 6,000 meters (over the Himalayas).
    Brief Summary
    provided by EOL authors

    Dresser Henry Eeles. A history of the birds of Europe, includig all the species inhabiting the western palaeartic region. London, self published 1871-1881 (vols.1-8), 1895-1896 (vol.9 Supplement). 9 vols. in 4to. 723 very fine coloured plates.

    Brief Summary
    provided by EOL authors

    Dresser Henry Eeles. A history of the birds of Europe, includig all the species inhabiting the western palaeartic region. London, self published 1871-1881 (vols.1-8), 1895-1896 (vol.9 Supplement). 9 vols. in 4to. 723 very fine coloured plates.

Comprehensive Description

Morphology

    Sexual Dimorphism
    provided by Fairbairn 2013
    Males usually larger than females, but females larger in some groups; slight Sexual Dimorphism in shape; diverse and pronounced Sexual Dimorphism in color and plumage, usually males more conspicuous.
    Morphology
    provided by Animal Diversity Web

    Other Physical Features: ectothermic ; bilateral symmetry

Development

    Growth and Development
    provided by EOL authors

    Hatching
    Hatching is a momentous event because it is switching gas exchange from the surface of the egg, to now using its lungs. Birds have an egg tooth, which is a small point on its upper bill that is used to excavate a ring in the egg. The air space in the egg is used by the bird to drill a hole in the egg. The birds have a very powerful hatching muscle on the back of the neck.

    Embryonated chick eggs: Eggs at hatching are usually about 18 days old (ish). Some people then use the eggs when they are 16 days old. Yet, there can often be communication between kids in the nest, and parents to the eggs. There are some calls that the kid in the egg can make to tell the parents what is going on. Thus, it seems to be that the young canfeelwhen inside the egg!

    There is a large change in morphology that occurs in the nestling period. The nestling period is from the time the first kid hatches to when the last kid fledges. Thus the nestling period leads to the fledging period. The act that goes from one to the other is the act of ‘fledging’. The fledging periods is from when the last kid fledges to when all the young are independent form the parents.

    Altricial birds:
    In these types of birds, the chicks are almost useless when they hatch. They are mostly featherless and their eyes are half closed. This is the form of full altricial. There are of course stages of altricial. Hummingbirds are extremely altricial.

    Semialtricial kids are unique as well. These birds often have some down feathers, and large feet. Its also dependent on the parents but hatches at an advanced state.

    A semi-precocial bird has its eyes wide-open and is covered in feathers.

    Precocial chicks, are completely down-covered. It can walk. Its wings are not big enough to fly but it can walk. It can follow its parents around and its eyes and brains are well developed.

    Superprecocial: mound builders
    Precocial: duck, shorebirds, quails, grouse, murrlets
    Altricial: songbirds, woodpeckers, parrots

    Character Altricial Precocial
    Eyes at hatching Closed Open
    Down Absent or sparse Present
    Mobility Immobile Mobile

    Transition from incubating to taking care of the birds when they hatch.

    Delivering food is an important aspect of parental care in altricial birds. The relationship between kids and adults must be very closely evolved when you have sharp bills (ie. Anhinga parent, and kids.

    Most birds have a sigmoidal growth curve (s-shaped). The biggest difference between the different sized birds is not that they start growing faster, but that as the other stops growing, the other just keeps on growing more and more.

    Endothermy is birds is unique. An altricial bird has no endothermy when it is born. It slowly gains endothermy as they begin to grow.

    The growth curves vary significantly amount species. For example, a curve-billed thrasher has a slow growth curve. They fledge when they weigh less than their parents. Cliff swallows, however, actually grow very fast and looses weight after it leaves the parents. This is most certainly an insurance solution that makes sure that it doesn’t starve.

    Tissue allocation hypothesis: Bob Brickleff:
    If you take a leg tissue, you can grow it or mature it, but you can’t do both at the same time. Thus, tissue allocation, refers to a decision to increase mass or increase maturation of the tissue. Quails, which are precocial, put a lot into the maintenance of their leg muscles. Thus, the growth of the leg muscles is much longer. This is because for a given amount of growth there is a given amount of maturation. Other species like starlings, don’t really need to walk (its altricial), so it can add mass quickly and worry later about maturation.

    The strategy of an altricial bird is to start with nothing and grow like mad! Te primitive state is the precocial state and the altricial state. Its believed that the altricial state has evolved to minimize the time for nest predators.

    Some birds secrete food for their kids: pidgeons produce crop milk. But flamingos and penguins also produce crop milk.

Identification Resources

Reproduction

    Reproduction
    provided by Animal Diversity Web

    Key Reproductive Features: gonochoric/gonochoristic/dioecious (sexes separate)

Citizen Science links