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<h1>Bird</h1><dl><dd><em>For other meanings of </em>bird<em>, see <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/bird__disambiguation_" title="Bird (disambiguation)">bird (disambiguation)</A>.</em><p>
</dd></dl><table   border="1" cellspacing="0" style="float:right; margin-left:20px;" cellpadding="2" ><tr>
<th  align="center" bgcolor=pink> <strong>Birds</strong>
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<td  align="center"> <IMG SRC="http://en.wikipedia.org/upload/6/66/Lemon-breasted_Flycatcher.jpg"><br>
<small>Lemon-bellied Flycatcher</small>
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<th  bgcolor="pink">#redirect

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<td > #redirect 
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</td><td > <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/animal" title="Animal">Animalia</A>
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<td > #redirect 
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</td><td > <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/chordate" title="Chordate">Chordata</A>
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<td > #redirect 
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</td><td > <strong>Aves</strong>
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<th  align="center" colspan="2" bgcolor=pink> <strong><A HREF="http://allwebhunt.com/wiki-article-tab.cfm/scientific_classification_1" title="Scientific classification">Orderss</A></strong>
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<td > Many - see text
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<strong>Birds</strong> are <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/biped" title="Biped">bipedal</A>, <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/homeothermic" title="Homeothermic">warm-blooded</A>, egg-laying <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/vertebrate" title="Vertebrate">vertebrates</A> characterized primarily by feathers, forelimbs modified as <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/wings" title="Wings">wings</A>, and hollow bones. There are almost 9000 known species of birds in the world.<p>
		
<p><table border="0" id="toc"><tr><td align="center">
<b>Table of contents</b> </td></tr><tr id='tocinside'><td align="left">
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<A CLASS="internal" HREF="#Introduction">1 Introduction</A><BR>
<A CLASS="internal" HREF="#Reproduction">2 Reproduction</A><BR>
<A CLASS="internal" HREF="#Respiration">3 Respiration</A><BR>
<div style="margin-left:2em;">
<A CLASS="internal" HREF="#Air flow through air sacs and lungs">3.1 Air flow through air sacs and lungs</A><BR>
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<A CLASS="internal" HREF="#Evolution">4 Evolution</A><BR>
<A CLASS="internal" HREF="#CLASS AVES">5 CLASS AVES</A><BR>
<A CLASS="internal" HREF="#Birds and humans">6 Birds and humans</A><BR>
<A CLASS="internal" HREF="#See also">7 See also</A><BR>
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<A NAME=""><H2>Introduction</H2><p>
Birds range in size from the tiny <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/hummingbird" title="Hummingbird">hummingbirds</A> to the huge <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/ostrich" title="Ostrich">Ostrich</A> and <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/emu" title="Emu">Emu</A>. <p>
Although most birds are characterised by flight, the <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/ratite" title="Ratite">ratites</A> are flightless, and several other species, particularly on islands, have also lost this ability. Flightless birds include the <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/penguin" title="Penguin">penguins</A>, Ostrich, <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/kiwi" title="Kiwi">kiwi</A>, and the extinct <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/dodo" title="Dodo">Dodo</A>. Flightless species are vulnerable to extinction when humans or the <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/mammal" title="Mammal">mammals</A> they introduce arrive in their habitat, for example the <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/great_auk" title="Great Auk">Great Auk</A>, flightless <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/rallidae" title="Rallidae">railss</A>, and the <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/moa" title="Moa">moa</A> of <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/list_of_new_zealand_birds" title="List of New Zealand birds"> New Zealand</A>.  <p>
Birds are a very differentiated class, with some feeding on <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/nectar" title="Nectar">nectar</A>, seeds, <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/insect" title="Insect">insects</A>, <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/rodent" title="Rodent">rodents</A>, <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/fish" title="Fish">fish</A>, carrion, or other birds. Most birds are <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/diurnal" title="Diurnal">diurnal</A>, or active during the day. Some birds, such as the owls and <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/nightjar" title="Nightjar">nightjars</A> are <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/nocturnal" title="Nocturnal">nocturnal</A> or <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/crepuscular" title="Crepuscular">crepuscular</A> (active during twilight hours). Many birds <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/bird_migration" title="Bird migration">migrate</A> long distances to utilise optimum habitats (e.g., <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/arctic_tern" title="Arctic Tern">Arctic Tern</A>) while others spend almost all their time at sea (e.g. the <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/wandering_albatross" title="Wandering Albatross">Wandering Albatross</A>). <p>
Common characteristics of birds are the ability to <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/flight" title="Flight">fly</A> using feathered <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/wings" title="Wings">wings</A>, a bony <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/beak" title="Beak">beak</A> with no teeth, the laying of hard-shelled <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/egg" title="Egg">eggs</A>, high <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/metabolism" title="Metabolism">metabolic</A> rate, and a light but strong <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/skeleton" title="Skeleton">skeleton</A>. Birds are among the most extensively studied animal groups, with hundreds of academic journals devoted to their study.<p>
To preen or groom their feathers, birds use their bills to brush away foreign particles.<p>
The birds of a region are called the <strong>avifauna</strong>. <p>
<A NAME=""><H2>Reproduction</H2><p>
Although most male birds have no external sex organs, the male does have two <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/testicle" title="Testicle">testes</A> which become hundreds of times larger during the breeding season to produce <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/sperm" title="Sperm">sperm</A>. The female's <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/ovary" title="Ovary">ovaries</A> also become larger, although only the left ovary actually functions.  <p>
In the males of species without a <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/penis" title="Penis">phallus</A> (see below), sperm is stored within the proctodeum compartment within the <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/cloaca" title="Cloaca">cloaca</A> prior to copulation. During <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/sexual_intercourse" title="Sexual intercourse">copulation</A>, the female moves her tail to the side and the male either mounts the female from behind or moves very close to her. He moves the opening of his cloaca, or vent, close to hers, so that the sperm can enter the female's cloaca, in what is referred to as a cloacal kiss. This can happen very fast, sometimes in less than one second.<p>
The sperm is stored in the female's cloaca for anywhere from a week to a year, depending on the species of bird. Then, one by one, eggs will descend from the female's ovaries and become fertilized by the male's sperm, before being subsequently laid by the female. The eggs will then continue their development in the nest.<p>
Many <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/wildfowl" title="Wildfowl">waterfowl</A> and some other birds, such as the ostrich and <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/turkey__bird_" title="Turkey (bird)">turkey</A>, do possess a phallus. Except during copulation, it is hidden within the proctodeum compartment within the cloaca, just inside the vent. The avian phallus differs from the <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/mammal" title="Mammal">mammalian</A> <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/penis" title="Penis">penis</A> in several ways, most importantly in that it is purely a copulatory organ and is not used for dispelling urine.<p>
After the eggs hatch, parent birds provide varying degrees of care in terms of food and protection. <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/precocial" title="Precocial">Precocial</A> birds can care for themselves independently within minutes of hatching; <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/altricial" title="Altricial">altricial</A> hatchlings are helpless, blind, and naked, and require extended parental care. The chicks of many ground-nesting birds such as partridges and waders are often able to run virtually immediately after hatching; such birds are referred to as <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/nidifugous" title="Nidifugous">nidifugous</A>. The young of hole-nesters, on the other hand, are often totally incapable of unassisted survival. "Fledging" is the process of a chick acquiring feathers until it can fly.<p>
<A NAME=""><H2>Respiration</H2><p>
<IMG SRC="http://en.wikipedia.org/upload/0/0f/Albaa.jpg">
Birds respire by a method of crosscurrent flow, ie: flow at a 90% angle.  There are three sections involved in <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/respiration" title="Respiration">respiration</A>.  These are the anterior air sacs  (interclavicular,  cervicals, & anterior thoracics), the <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/lung" title="Lung">lungs</A>, and the posterior air sacs (posterior thoracics & abdominals).  It takes a bird two full breaths (inhaling and exhaling), to cycle air through.<p>
<A NAME=""><H3>Air flow through air sacs and lungs</H3>
<ul><li>First inhalation:  air flows through the <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/trachea" title="Trachea">trachea</A> and <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/bronchus" title="Bronchus">bronchi</A> into the posterior air sacs. 
</li><li>First exhalation: air flows from the posterior air sacs to the lungs
</li><li>Second inhalation: air flows from the lungs to the anterior air sacs
</li><li>Second exhalation: air flows from the anterior sacs back through the trachea and out of the body.<p>
</li></ul>In birds, air flows in only one direction.  Because of this method, birds are able to <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/diffusion" title="Diffusion">diffuse</A> more <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/oxygen" title="Oxygen">oxygen</A> into their blood.  Unlike humans and other mammals, there is no mixing of oxygen rich air and <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/carbon_dioxide" title="Carbon dioxide">carbon dioxide</A> rich air.  Thus, the <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/partial_pressure" title="Partial pressure">partial pressure</A> of oxygen in a bird's lungs is the same as the environment.  This is also why you would more likely see a bird on <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/mount_everest" title="Mount Everest">Mount Everest</A>, than say a <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/mouse" title="Mouse">mouse</A>.   <p>
<A NAME=""><H2>Evolution</H2><p>
Birds are generally considered to have evolved from <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/theropoda" title="Theropoda">theropod</A> <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/dinosaur" title="Dinosaur">dinosaurss</A>.<p>
The exact boundary between <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/dinosaur" title="Dinosaur">dinosaurss</A> and birds is unclear, especially with the recent discoveries in North-east <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/china" title="China">China</A> (<A HREF="http://allwebhunt.com/wiki-article-tab.cfm/liaoning" title="Liaoning">Liaoning</A> Province) demonstrating that many small <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/theropoda" title="Theropoda">theropod</A> <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/dinosaur" title="Dinosaur">dinosaurs</A> had feathers.  It should be noted that although ornithischian dinosaurs share the same hip structure as birds (bird-hipped), birds originated from the saurischian or lizard-hipped dinosaurs, and so arrived at this condition independently.  In fact, it developed a third time among a peculiar group of theropods, the Therizinosauridae. <p>
The early bird <em><A HREF="http://allwebhunt.com/wiki-article-tab.cfm/archaeopteryx" title="Archaeopteryx">Archaeopteryx</A></em>, from the <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/jurassic" title="Jurassic">Jurassic</A>, is well-known as one of the first "missing links" to be found in support of <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/evolution" title="Evolution">evolution</A> in the late <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/19th_century" title="19th century">19th century</A>. It remains the most primitive known bird.<p>
Modern birds are classified in Neornithes. Extinct birds include the Confuciusornithidae, Enantiornithes, <em>Ichthyornis</em>, and Hesperornithiformes, a group of flightless divers resembling grebes. <p>
The flightless Palaeognaths, the Ostrich group, were first to diverge from the avian lineage, and it is now thought that the basal divergence from the remaining Neognathes was that of the Galloanseri, the superorder containing the <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/anseriformes" title="Anseriformes">Anseriformes</A> (<A HREF="http://allwebhunt.com/wiki-article-tab.cfm/duck" title="Duck">ducks</A>, <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/goose" title="Goose">geese</A> and <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/swans" title="Swans">swans</A>), and the <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/galliformes" title="Galliformes">Galliformes</A> (the pheasants, <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/grouse" title="Grouse">grouse</A> and their allies. See the chart.<p>
<div style="float:right; margin-left:15px; margin-right:5px; width:278px; text-align:center">
<IMG SRC="http://en.wikipedia.org/upload/2/23/Galloanseri2.png"></div><p>
<A HREF="http://allwebhunt.com/wiki-article-tab.cfm/charles_sibley" title="Charles Sibley">Sibley</A> & Ahlquist's <em>Phylogeny and Classification of Birds</em> (1990) is a landmark work on the classification of birds (although frequently debated and constantly revised).<p>
<A NAME=""><H2>CLASS AVES</H2>
See <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/list_of_birds" title="List of birds">List of birds</A> for a more detailed summary
<ul><li><A HREF="http://allwebhunt.com/wiki-article-tab.cfm/ratite" title="Ratite">Struthioniformes</A>, Ostrich, emus, kiwis, and allies
</li><li><A HREF="http://allwebhunt.com/wiki-article-tab.cfm/tinamou" title="Tinamou">Tinamiformes</A>, tinamous
</li><li><A HREF="http://allwebhunt.com/wiki-article-tab.cfm/anseriformes" title="Anseriformes">Anseriformes</A>, waterfowl
</li><li><A HREF="http://allwebhunt.com/wiki-article-tab.cfm/galliformes" title="Galliformes">Galliformes</A>, fowl
</li><li><A HREF="http://allwebhunt.com/wiki-article-tab.cfm/penguin" title="Penguin">Sphenisciformes</A>, penguins
</li><li><A HREF="http://allwebhunt.com/wiki-article-tab.cfm/loon" title="Loon">Gaviiformes</A>, loons
</li><li><A HREF="http://allwebhunt.com/wiki-article-tab.cfm/grebe" title="Grebe">Podicipediformes</A>, grebes 
</li><li><A HREF="http://allwebhunt.com/wiki-article-tab.cfm/procellariiformes" title="Procellariiformes">Procellariiformes</A>, albatrosses, petrels, and allies
</li><li><A HREF="http://allwebhunt.com/wiki-article-tab.cfm/pelecaniformes" title="Pelecaniformes">Pelecaniformes</A>, pelicans and allies
</li><li><A HREF="http://allwebhunt.com/wiki-article-tab.cfm/ciconiiformes" title="Ciconiiformes">Ciconiiformes</A>, storks and allies
</li><li><A HREF="http://allwebhunt.com/wiki-article-tab.cfm/flamingo" title="Flamingo">Phoenicopteriformes</A>, flamingos
</li><li><A HREF="http://allwebhunt.com/wiki-article-tab.cfm/accipitriformes" title="Accipitriformes">Accipitriformes</A>, eagles, hawks and allies 
</li><li><A HREF="http://allwebhunt.com/wiki-article-tab.cfm/falconiformes" title="Falconiformes">Falconiformes</A>, falcons
</li><li><A HREF="http://allwebhunt.com/wiki-article-tab.cfm/buttonquail" title="Buttonquail">Turniciformes</A>, button-quail
</li><li><A HREF="http://allwebhunt.com/wiki-article-tab.cfm/gruiformes" title="Gruiformes">Gruiformes</A>, cranes and allies
</li><li><A HREF="http://allwebhunt.com/wiki-article-tab.cfm/charadriiformes" title="Charadriiformes">Charadriiformes</A>, plovers and allies
</li><li><A HREF="http://allwebhunt.com/wiki-article-tab.cfm/sandgrouse" title="Sandgrouse">Pteroclidiformes</A>, sandgrouse
</li><li><A HREF="http://allwebhunt.com/wiki-article-tab.cfm/columbiformes" title="Columbiformes">Columbiformes</A>, doves and pigeons
</li><li><A HREF="http://allwebhunt.com/wiki-article-tab.cfm/psittaciformes" title="Psittaciformes">Psittaciformes</A>, parrots and allies
</li><li><A HREF="http://allwebhunt.com/wiki-article-tab.cfm/cuculiformes" title="Cuculiformes">Cuculiformes</A>, cuckoos
</li><li><A HREF="http://allwebhunt.com/wiki-article-tab.cfm/owl" title="Owl">Strigiformes</A>, owls
</li><li><A HREF="http://allwebhunt.com/wiki-article-tab.cfm/caprimulgiformes" title="Caprimulgiformes">Caprimulgiformes</A>, nightjars and allies
</li><li><A HREF="http://allwebhunt.com/wiki-article-tab.cfm/apodiformes" title="Apodiformes">Apodiformes</A>, swifts
</li><li><A HREF="http://allwebhunt.com/wiki-article-tab.cfm/coraciiformes" title="Coraciiformes">Coraciiformes</A>, kingfishers
</li><li><A HREF="http://allwebhunt.com/wiki-article-tab.cfm/piciformes" title="Piciformes">Piciformes</A>, woodpeckers and allies
</li><li><A HREF="http://allwebhunt.com/wiki-article-tab.cfm/trogon" title="Trogon">Trogoniformes</A>, trogons
</li><li><A HREF="http://allwebhunt.com/wiki-article-tab.cfm/mousebird" title="Mousebird">Coliiformes</A>, mousebirds
</li><li><A HREF="http://allwebhunt.com/wiki-article-tab.cfm/passerine" title="Passerine">Passeriformes</A>, passerines<p>
</li></ul><A NAME=""><H2>Birds and humans</H2><p>
Birds are an important food source for <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/human" title="Human">humans</A>. The most commonly eaten species is the domestic <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/chicken" title="Chicken">chicken</A> and its <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/egg" title="Egg">eggs</A>, although <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/goose" title="Goose">geese</A>, pheasants, <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/turkey__bird_" title="Turkey (bird)">turkeyss</A> and <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/duck" title="Duck">ducks</A> are also widely eaten. Other birds that have been utilized for food include <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/emu" title="Emu">emus</A>, ostriches, pigeons, <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/grouse" title="Grouse">grouse</A>, <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/quail" title="Quail">quails</A>, <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/doves" title="Doves">doves</A>, woodcocks, songbirds and others, including small <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/passerine" title="Passerine">passerines</A> such as finches..<p>
At one time <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/swans" title="Swans">swans</A> and <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/flamingo" title="Flamingo">flamingos</A> were delicacies of the rich and powerful, although these are generally protected now.<p>
Many species have become extinct through over-hunting, such as the <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/passenger_pigeon" title="Passenger Pigeon">Passenger Pigeon</A>, and many others have become endangered or extinct through <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/habitat" title="Habitat">habitat</A> destruction, <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/deforestation" title="Deforestation">deforestation</A> and intensive <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/agriculture" title="Agriculture">agriculture</A> being common causes for declines.<p>
<IMG SRC="http://en.wikipedia.org/upload/b/bd/Penguinu.jpg"><p>
Numerous species have come to depend on human activies for food and are widespread to the point of being pests. For example the common pigeon or <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/rock_dove" title="Rock Dove">Rock Dove</A> (<em>Columba livia</em>) thrives in urban areas around the world. In North America, House Sparrows (<em>Passer domesticus</em>), European Starlings (<em>Sturnus vulgaris</em>), and House Finches (<em>Carpodacus mexicanus</em>) are similarly widespread.<p>
Other birds have been used by humans: for example <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/rock_dove" title="Rock Dove">Homing pigeons</A> to carry messages (many are still kept for sport), falcons for hunting, cormorants for fishing. <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/chicken" title="Chicken">Chickens</A> and pigeons are popular subjects in experimental research in <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/biology" title="Biology">biology</A> and <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/comparative_psychology" title="Comparative psychology">comparative psychology</A>. As birds are extra-sensitive to toxins, the <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/canary" title="Canary">Canary</A> was often used in <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/coal_mining" title="Coal mining">coal mines</A> to indicate the presence of poisonous gases, so that the miners could escape.<p>
Colorful, particularly tropical, birds (e.g., <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/parrot" title="Parrot">parrotss</A>, and mynahs) are often kept as <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/pet_1" title="Pet">pets</A> although this has led to smuggling of some endangered species; <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/convention_on_the_international_trade_in_endangered_spec" title="Convention on the International Trade in Endangered Species of Wild Flora and Fauna">CITES</A> does considerable work to deter this.<p>
Bird diseases that can be contracted by humans include: <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/psittacosis" title="Psittacosis">psittacosis</A>, salmonellosis, campylobacteriosis, Newcastle's disease, mycobacteriosis (avian <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/tuberculosis" title="Tuberculosis">tuberculosis</A>), <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/influenza" title="Influenza">influenza</A>, <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/giardiasis" title="Giardiasis">giardiasis</A>, and cryptosporiadiosis.<p>
Few birds use chemical defences against predators.  Tubenoses can eject an unpleasant slime against an aggressor, and some species of <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/pitohui" title="Pitohui">pitohui</A>, found in <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/new_guinea" title="New Guinea">New Guinea</A> secrete a powerful <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/neurotoxin" title="Neurotoxin">neurotoxin</A> in their feathers.<p>
<A NAME=""><H2>See also</H2>
<ul><li> <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/archaeopteryx" title="Archaeopteryx">Archaeopteryx</A>
</li><li> <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/avian_pallium" title="Avian pallium">Avian pallium</A>
</li><li> <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/carinatae" title="Carinatae">Carinatae</A>
</li><li> <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/extinct_birds" title="Extinct birds">extinct birds</A>
</li><li> <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/conservation_status" title="Conservation status">conservation status</A>
</li><li> <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/bird_migration" title="Bird migration">bird migration</A>
</li><li> <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/anting__bird_activity_" title="Anting (bird activity)">anting (bird activity)</A>
</li><li> <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/bird_ringing" title="Bird ringing">bird ringing</A> (banding)
</li><li> <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/birdfeeding" title="Birdfeeding">birdfeeding</A>
</li><li> <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/birdwatching" title="Birdwatching">birding</A>
</li><li> <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/ornithology" title="Ornithology">ornithology</A>
</li><li> <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/oology" title="Oology">oology</A>
</li><li> <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/the_biology_of_eggs" title="The biology of eggs">egg biology</A>
</li><li> <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/list_of_regional_bird_lists" title="List of regional bird lists">Regional and country bird lists</A>:<p>
</li></ul>
Bird families and taxonomic discussion are given in <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/list_of_birds" title="List of birds">list of birds</A> and <A HREF="http://allwebhunt.com/wiki-article-tab.cfm/sibley_ahlquist_taxonomy" title="Sibley-Ahlquist taxonomy">Sibley-Ahlquist taxonomy</A>.<p>
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