Birds World

1845 Pages·2011·23.5 MB·English

Birds World
Birds | Aviculture | Bird migration flyways | Bird topography | Birds by classification
| Birds by geography | Birds of prey | Birdwatching | Bird diseases | Extinct birds | Famous birds
| Feathers | Fictional birds | Flightless birds | Heraldic birds | Oology | Poultry | Prehistoric birds | Seabird
| Shorebirds | Swifts | Wading birds | License | Index
Birds
Birds are bipedal, warm-blooded, oviparous vertebrate Fossil range: Late Jurassic - Recent
animals characterized primarily by feathers, forelimbs
modified as wings, and (in most) hollow bones.
Birds range in size from the tiny hummingbirds to the huge
Ostrich and Emu. Depending on the taxonomic viewpoint,

there are about 8,800–10,200 living bird species (and about
120–130 that have become extinct in the span of human
history) in the world, making them the most diverse class
of terrestrial vertebrates.
Birds feed on nectar, plants, seeds, insects, fish, mammals, Superb Fairy-wren, Malurus cyaneus, juvenile
carrion, or other birds.
Scientific classification
Kingdom: Animalia
Most birds are diurnal, or active during the day, but some
birds, such as the owls and nightjars, are nocturnal or Phylum: Chordata
crepuscular (active during twilight hours), and many
Subphylum: Vertebrata
coastal waders feed when the tides are appropriate, by day
(unranked) Archosauria
or night.
Class: Aves
Linnaeus, 1758
Many birds migrate long distances to utilise optimum
habitats (e.g., Arctic Tern) while others spend almost all their time at sea (e.g. the Wandering Albatross).
Some, such as Common Swifts, stay aloft for days at a time, even sleeping on the wing.
Common characteristics of birds include a bony beak with no teeth, the laying of hard-shelled eggs, high
metabolic rate, a 4-chambered heart, and a light but strong skeleton. Most birds are characterised by
flight, though the ratites are flightless, and several other species, particularly on islands, have also lost
this ability. Flightless birds include the penguins, ostrich, kiwi, and the extinct Dodo. Flightless species
are vulnerable to extinction when humans or the mammals they introduce arrive in their habitat. The
Great Auk, flightless rails, and the moa of New Zealand, for example, all became extinct due to human
influence.
Birds are among the most extensively studied of all animal groups. Hundreds of academic journals and
thousands of scientists are devoted to bird research, while amateur enthusiasts (called birdwatchers or,
more commonly, birders) probably number in the millions.
by MultiMedia and Nicolae Sfetcu
This guide is licensed under the GNU Free Documentation License. It uses material from the Wikipedia.
Birds
Alektorophobia | Avian incubation | Bird abatement | Bird anatomy | Bird bath | Bird feeding | Bird flight
| Bird intelligence | Nidification
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Birds
Contents
1 High-level taxonomy
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2 Bird orders
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(cid:0)m 2.1 Extinct bird orders
3 Evolution
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4 Bird anatomy
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5 Nesting
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(cid:0)m 5.1 Eggs
(cid:0)m 5.2 Social systems and parental care
6 Birds and humans
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7 Threats to birds
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8 Trivia
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9 References
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10 External links
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High-level taxonomy
Birds are categorised as a biological class, Aves. The earliest known species of this class is
Archaeopteryx lithographica, from the Late Jurassic period. According to the most recent consensus,
Aves and a sister group, the order Crocodilia, together form a group of unnamed rank, the Archosauria.
Phylogenetically, Aves is usually defined as all descendants of the most recent common ancestor of
modern birds (or of a specific modern bird species like Passer domesticus), and Archaeopteryx. Modern
phylogenies place birds in the dinosaur clade Theropoda.
Modern birds are divided into two superorders, the Paleognathae (mostly flightless birds like ostriches),
and the wildly diverse Neognathae, containing all other birds.
Bird orders

Relationships between bird orders according the
Sibley-Ahlquist taxonomy. "Galloanseri" is now
considered a superorder Galloanserae.
This is a list of the taxonomic orders in the class Aves. The list of birds gives a more detailed summary,
including families.
Paleognathae:
Struthioniformes, Ostrich, emus, kiwis, and allies
●
Tinamiformes, tinamous
Neognathae:
Anseriformes, waterfowl
●
Galliformes, fowl
Gaviiformes, loons
Podicipediformes, grebes
Procellariiformes, albatrosses, petrels, and allies
Sphenisciformes, penguins
Pelecaniformes, pelicans and allies
Ciconiiformes, storks and allies
Phoenicopteriformes, flamingos
Accipitriformes, eagles, hawks and allies
Falconiformes, falcons
Turniciformes, button-quail
Gruiformes, cranes and allies
Charadriiformes, gulls, plovers and allies
Pteroclidiformes, sandgrouse
Columbiformes, doves and pigeons
Psittaciformes, parrots and allies
Cuculiformes, cuckoos, turacos, hoatzin
Strigiformes, owls
Caprimulgiformes, nightjars and allies
Apodiformes, swifts
Trochiliformes, hummingbirds
Coraciiformes, kingfishers
Piciformes, woodpeckers and allies
Trogoniformes, trogons
Coliiformes, mousebirds
Passeriformes, passerines
Note: This is the traditional classification (the so-called Clements order). A more recent, radically
different classification based on molecular data has been developed (the so-called Sibley-Monroe
classification or Sibley-Ahlquist taxonomy). This has influenced taxonomical thinking considerably,
with the Galloanserae proving well-supported by recent molecular, fossil and anatomical evidence
[citation needed]. With increasingly good evidence, it has become possible by 2006 to test the major
proposals of the Sibley-Ahlquist taxonomy. The results are often nothing short of astounding, see e.g.
Charadriiformes or Caprimulgiformes.
Extinct bird orders
A wide variety of bird groups became extinct during the Mesozoic era and left no modern descendants.
These include the Order Archaeopterygiformes, Order Confuciusornithiformes, toothed seabirds like the
Hesperornithiformes and Ichthyornithes, and the diverse Subclass Enantiornithes ("opposite birds").
For a complete listing of prehistoric bird groups, see Fossil birds.

Shoebill, Balaeniceps rex
Evolution
There is significant evidence that birds evolved from theropod dinosaurs, specifically, that birds are
members of Maniraptora, a group of theropods which includes dromaeosaurs and oviraptorids, among
others.[1] As more non-avian theropods that are closely related to birds are discovered, the formerly
clear distinction between non-birds and birds becomes less so. Recent discoveries in northeast China
(Liaoning Province) demonstrating that many small theropod dinosaurs had feathers contribute to this
ambiguity.
The basal bird Archaeopteryx, from the Jurassic, is well-known as one of the first "missing links" to be
found in support of evolution in the late 19th century, though it is not considered a direct ancestor of
modern birds. Confuciusornis is another early bird; it lived in the Early Cretaceous. Both may be
predated by Protoavis texensis, though the fragmentary nature of this fossil leaves it open to
considerable doubt if this was a bird ancestor. Other Mesozoic birds include the Enantiornithes,
Yanornis, Ichthyornis, Gansus and the Hesperornithiformes, a group of flightless divers resembling
grebes and loons.
The recently discovered dromaeosaur Cryptovolans was capable of powered flight, possessed a sternal
keel and had ribs with uncinate processes. In fact, Cryptovolans makes a better "bird" than
Archaeopteryx which is missing some of these modern bird features. Because of this, some
paleontologists have suggested that dromaeosaurs are actually basal birds whose larger members are
secondarily flightless, i.e. that dromaeosaurs evolved from birds and not the other way around. Evidence
for this theory is currently inconclusive, but digs continue to unearth fossils (especially in China) of the
strange feathered dromaeosaurs. At any rate, it is fairly certain that avian flight existed in the mid-
Jurassic and was "tried out" in several lineages and variants by the mid-Cretaceous.

Snowy Owl, Bubo scandiacus
Although ornithischian (bird-hipped) dinosaurs share the same hip structure as birds, birds actually
originated from the saurischian (lizard-hipped) dinosaurs (if the dinosaurian origin theory is correct),
and thus arrived at their hip structure condition independently. In fact, the bird-like hip structure also
developed a third time among a peculiar group of theropods, the Therizinosauridae.
An alternate theory to the dinosaurian origin of birds, espoused by a few scientists (most notably Lary
Martin and Alan Feduccia), states that birds (including maniraptoran "dinosaurs") evolved from early
archosaurs like Longisquama, a theory which is contested by most other scientists in paleontology, and
by experts in feather development and evolution such as R.O. Prum. See the Longisquama article for
more on this alternative.
Modern birds are classified in Neornithes, which are now known to have evolved into some basic
lineages by the end of the Cretaceous. The Neornithes are split into the Paleognathae and Neognathae.
The paleognaths include the tinamous (found only in Central and South America) and the ratites. The
ratites are large flightless birds, and include ostriches, cassowaries, kiwis and emus (though some
scientists suspect that the ratites represent an artificial grouping of birds which have independently lost
the ability to fly in a number of unrelated lineages). The basal divergence from the remaining
Neognathes was that of the Galloanseri, the superorder containing the Anseriformes (ducks, geese and
swans), and the Galliformes (the pheasants, grouse, and their allies). See the chart for more information.
The classification of birds is a contentious issue. Sibley & Ahlquist's Phylogeny and Classification of
Birds (1990) is a landmark work on the classification of birds (although frequently debated and
constantly revised). A preponderance of evidence seems to suggest that the modern bird orders
constitute accurate taxa. However, scientists are not in agreement as to the relationships between the
orders; evidence from modern bird anatomy, fossils and DNA have all been brought to bear on the
problem but no strong consensus has emerged. More recently, new fossil and molecular evidence is
providing an increasingly clear picture of the evolution of modern bird orders.

Anatomy of a typical bird
Bird anatomy
Main article: bird anatomy
Birds have a body plan that shows so many unusual adaptations (mostly aiding flight) that birds have
earned their own unique class in the vertebrate phylum.
Nesting
Eggs
All birds lay amniotic eggs[2] with hard shells made mostly of calcium carbonate. Non-passerines
typically have white eggs, except in some ground-nesting groups such as the Charadriiformes,
sandgrouse and nightjars, where camouflage is necessary, and some parasitic cuckoos which have to
match the passerine host's egg. Most passerines, in contrast, lay coloured eggs, even if, like the tits they
are hole-nesters.
The brown or red protoporphyrin markings on passerine eggs reduce brittleness and are a substitute for
calcium when that element is in short supply. The colour of individual eggs is genetically influenced,
and appears to be inherited through the mother only, suggesting that the gene responsible for
pigmentation is on the sex determining W chromosome (female birds are WZ, males ZZ).
The eggs are laid in a nest, which may be anything from a bare cliff ledge or ground scrape to elaboratey
decorated structures such as those of the oropendolas.
Social systems and parental care
The three mating systems that predominate among birds are polyandry, polygyny, and monogamy.
Monogamy is seen in approximately 91% of all bird species. Polygyny constitutes 2% of all birds and
polyandry is seen in less than 1%. Monogamous species of males and females pair for the breeding
season. In some cases, the individuals may pair for life.
One reason for the high rate of monogamy among birds is the fact that male birds are just as adept at
parental care as females. In most groups of animals, male parental care is rare, but in birds it is quite
common; in fact, it is more extensive in birds than in any other vertebrate class. In birds, male care can
be seen as important or essential to female fitness. "In one form of monogamy such as with obligate
[3]
monogamy a female cannot rear a litter without the aid of a male" .