1 Skeletal system
1.1 Skull 1.2 Feet
2 Muscular system 3 Integumentary system
3.1 Scales 3.2 Rhamphotheca and podotheca 3.3 Beak
4 Respiratory system
6.1 Drinking behavior
7 Reproductive and urogenital systems
8 Nervous system 9 Immune system
9.1 Bursa of Fabricius
9.1.1 Function 9.1.2 Anatomy
10 See also 11 References 12 External links
A stylised dove skeleton. Key: 1. skull 2. cervical vertebrae 3. furcula 4. coracoid 5. uncinate processes of ribs 6. keel 7. patella 8. tarsometatarsus 9. digits 10. tibia (tibiotarsus) 11. fibia (tibiotarsus) 12. femur 13. ischium (innominate) 14. pubis (innominate) 15. illium (innominate) 16. caudal vertebrae 17. pygostyle 18. synsacrum 19. scapula 20. dorsal vertebrae 21. humerus 22. ulna 23. radius 24. carpus (carpometacarpus) 25. metacarpus (carpometacarpus) 26. digits 27. alula
The bird skeleton is highly adapted for flight. It is extremely lightweight but strong enough to withstand the stresses of taking off, flying, and landing. One key adaptation is the fusing of bones into single ossifications, such as the pygostyle. Because of this, birds usually have a smaller number of bones than other terrestrial vertebrates. Birds also lack teeth or even a true jaw, instead having a beak, which is far more lightweight. The beaks of many baby birds have a projection called an egg tooth, which facilitates their exit from the amniotic egg, and that falls off once it has done its job. Birds have many bones that are hollow (pneumatized) with criss-crossing struts or trusses for structural strength. The number of hollow bones varies among species, though large gliding and soaring birds tend to have the most. Respiratory air sacs often form air pockets within the semi-hollow bones of the bird's skeleton. The bones of diving birds are often less hollow than those of non-diving species. Penguins, loons and puffins are without pneumatized bones entirely. Flightless birds, such as ostriches and emus, demonstrate osseous pneumaticity, possessing pneumatized femurs and, in the case of the emu, pneumatized cervical vertebrae.
Air-sacs and their distribution
Birds also have more cervical (neck) vertebrae than many other animals; most have a highly flexible neck consisting of 13-25 vertebrae. Birds are the only vertebrates to have fused clavicles (collarbone) (the furcula or wishbone) or a keeled sternum or breastbone. The keel of the sternum serves as an attachment site for the muscles used for flight or, similarly, for swimming, in penguins. Again, flightless birds, such as ostriches, which do not have highly developed pectoral muscles, lack a pronounced keel on the sternum. Swimming birds have a wide sternum, while walking birds have a long or high sternum and flying birds have a sternum width and height that are nearly equal. Birds have uncinate processes on the ribs. These are hooked extensions of bone which help to strengthen the rib cage by overlapping with the rib behind them. This feature is also found in the tuatara (Sphenodon). They also have a greatly elongate tetradiate pelvis, similar to some reptiles. The hind limb has an intra-tarsal joint found also in some reptiles. There is extensive fusion of the trunk vertebrae as well as fusion with the pectoral girdle. They have a diapsid skull, as in reptiles, with a pre-lachrymal fossa (present in some reptiles). The skull has a single occipital condyle. The vertebral column is divided into four sections of vertebrae: cervical (11-25) (neck), trunk (dorsal or throacic) vertebrae usually fused in the notarium, synsacrum (fused vertebrae of the back, also fused to the hips (pelvis)), and pygostyle (tail). The chest consists of the furcula (wishbone) and coracoid (collar bone), which, together with the scapula (see below), form the pectoral girdle. The side of the chest is formed by the ribs, which meet at the sternum (mid-line of the chest). The shoulder consists of the scapula (shoulder blade), coracoid, and humerus (upper arm). The humerus joins the radius and ulna (forearm) to form the elbow. The carpus and metacarpus form the "wrist" and "hand" of the bird, and the digits are fused together. The bones in the wing are extremely light so that the bird can fly more easily. The hips consist of the pelvis, which includes three major bones: the ilium (top of the hip), ischium (sides of hip), and pubis (front of the hip). These are fused into one (the innominate bone). Innominate bones are evolutionary significant in that they allow birds to lay eggs. They meet at the acetabulum (hip socket) and articulate with the femur, which is the first bone of the hind limb. The upper leg consists of the femur. At the knee joint, the femur connects to the tibiotarsus (shin) and fibula (side of lower leg). The tarsometatarsus forms the upper part of the foot, digits make up the toes. The leg bones of birds are the heaviest, contributing to a low center of gravity, which aids in flight. A bird's skeleton accounts for only about 5% of its total body weight Skull The skull consists of five major bones: the frontal (top of head), parietal (back of head), premaxillary and nasal (top beak), and the mandible (bottom beak). The skull of a normal bird usually weighs about 1% of the bird's total body weight. The eye occupies a considerable amount of the skull and is surrounded by a sclerotic eye-ring, a ring of tiny bones. This characteristic is also seen in reptiles.
The typical cranial anatomy of a bird. Pmx= premaxilla, M= maxilla, D= dentary, V= vomer, Pal= palatine, Pt= Pterygoid, Lc= Lacrimal
Broadly speaking, avian skulls consist of many small, non-overlapping
bones. Paedomorphosis, maintenance of the ancestral state in adults,
is thought to have facilitated the evolution of the avian skull. In
essence, adult bird skulls will resemble the juvenile form of their
theropod dinosaur ancestors. As the avian lineage has progressed
and has paedomorphosis has occurred, they have lost the postorbital
bone behind the eye, the ectopterygoid at the back of the palate, and
teeth. The palate structures have also become greatly altered
with changes, mostly reductions, seen in the ptyergoid, palatine, and
jugal bones. A reduction in the adductor chambers has also occurred
 These are all conditions seen in the juvenile form of their
ancestors. The premaxillary bone has also hypertrophied to form the
beak while the maxilla has become diminished, as suggested by both
developmental  and paleontological  studies. This expansion
into the beak has occurred in tandem with the loss of a functional
hand and the deveopmental of a point at the front of the beak that
resembles a "finger". Interestingly, the premaxilla is also known
to play a large role in feeding behaviours in fish.
The structure of the avian skull has important implications for their
feeding behaviours. Birds show independent movement of the skull bones
known as cranial kinesis.
Cranial kinesis in birds occurs in several
forms, but all of the different varieties are all made possible by the
anatomy of the skull. Animals with large, overlapping bones (including
the ancestors of modern birds ) have akinetic (non-kinetic) skulls
(I.e.). For this reason it has been argued that the
paedomorphic bird beak can be seen as an evolutionary innovation.
Types of bird feet
Birds' feet are classified as anisodactyl, zygodactyl, heterodactyl,
syndactyl or pamprodactyl. Anisodactyl is the most common
arrangement of digits in birds, with three toes forward and one back.
This is common in songbirds and other perching birds, as well as
hunting birds like eagles, hawks, and falcons.
Syndactyly, as it occurs in birds, is like anisodactyly, except that
the third and fourth toes (the outer and middle forward-pointing
toes), or three toes, are fused together, as in the belted kingfisher
Ceryle alcyon. This is characteristic of
The supracoracoideus works using a pulley like system to lift the wing while the pectorals provide the powerful downstroke
Most birds have approximately 175 different muscles, mainly controlling the wings, skin, and legs. The largest muscles in the bird are the pectorals, or the breast muscles, which control the wings and make up about 15 - 25% of a flighted bird's body weight. They provide the powerful wing stroke essential for flight. The muscle medial to (underneath) the pectorals is the supracoracoideus. It raises the wing between wingbeats. Both muscle groups attach to the keel of the sternum. This is remarkable, because other vertebrates have the muscles to raise the upper limbs generally attached to areas on the back of the spine. The supracoracoideus and the pectorals together make up about 25 – 35% of the bird's full body weight. The skin muscles help a bird in its flight by adjusting the feathers, which are attached to the skin muscle and help the bird in its flight maneuvers. There are only a few muscles in the trunk and the tail, but they are very strong and are essential for the bird. The pygostyle controls all the movement in the tail and controls the feathers in the tail. This gives the tail a larger surface area which helps keep the bird in the air. Integumentary system See also: Comb (anatomy), Lore (anatomy), and Gular skin
The scales of birds are composed of keratin, like beaks, claws, and
spurs. They are found mainly on the toes and tarsi (lower leg of
birds), usually up to the tibio-tarsal joint, but may be found further
up the legs in some birds. In many of the eagles and owls the legs are
feathered down to (but not including) their toes. Most
bird scales do not overlap significantly, except in the cases of
kingfishers and woodpeckers. The scales and scutes of birds were
originally thought to be homologous to those of reptiles and mammals
(such as the pangolin); however, more recent research suggests
that scales in birds re-evolved after the evolution of
Cancella – minute scales which are really just a thickening and hardening of the skin, crisscrossed with shallow grooves. Scutella – scales that are not quite as large as scutes, such as those found on the caudal, or hind part, of the chicken metatarsus. Scutes – the largest scales, usually on the anterior surface of the metatarsus and dorsal surface of the toes.
The rows of scutes on the anterior of the metatarsus can be called an
"acrometatarsium" or "acrotarsium".
Reticula are located on the lateral and medial surfaces (sides) of the
foot and were originally thought to be separate scales. However,
histological and evolutionary developmental work in this area revealed
that these structures lack beta-keratin (a hallmark of reptilian
scales) and are entirely composed of alpha-keratin.  This,
along with their unique structure, has led to the suggestion that
these are actually feather buds that were arrested early in
Rhamphotheca and podotheca
The bills of many waders have Herbst corpuscles which help them find
prey hidden under wet sand, by detecting minute pressure differences
in the water. All extant birds can move the parts of the upper jaw
relative to the brain case. However this is more prominent in some
birds and can be readily detected in parrots.
The region between the eye and bill on the side of a bird's head is
called the lore. This region is sometimes featherless, and the skin
may be tinted, as in many species of the cormorant family.
The scaly covering present on the foot of the birds is called
Main article: Beak
The beak, bill, or rostrum is an external anatomical structure of
birds which is used for eating and for grooming, manipulating objects,
killing prey, fighting, probing for food, courtship and feeding young.
Although beaks vary significantly in size, shape and color, they share
a similar underlying structure. Two bony projections—the upper and
lower mandibles—covered with a thin keratinized layer of epidermis
known as the rhamphotheca. In most species, two holes known as nares
lead to the respiratory system.
The arrangement of the air sacs, and lungs in birds
The anatomy of bird's respiratory system, showing the relationships of the trachea, primary and intra-pulmonary bronchi, the dorso- and ventro-bronchi, with the parabronchi running between the two. The posterior and anterior air sacs are also indicated, but not to scale.
Inhalation-exhalation cycle in birds.
Due to the high metabolic rate required for flight, birds have a high oxygen demand. Their highly effective respiratory system helps them meet that demand. Although birds have lungs, these are fairly rigid structures, which do not expand and contract as they do in mammals, reptiles and many amphibians. The structures that act as the bellows which ventilate the lungs, are the air sacs distributed throughout much of the birds' bodies. Although the bird lungs are smaller than those in mammals of comparable size, the air sacs account for 15% of the total body volume, compared to the 7% devoted to the alveoli which act as the bellows in mammals. The walls of these air sacs do not have a good blood supply and so do not play a direct role in gas exchange. They act like a set of bellows which move air unidirectionally through the parabronchi of the rigid lungs. Birds lack a diaphragm, and therefore use their intercostal and abdominal muscles to expand and contract their entire thoraco-abdominal cavities, thus rhythmically changing the volumes of all their air sacs in unison (illustration on the right). The active phase of respiration in birds is exhalation, requiring contraction of their muscles of respiration. Relaxation of these muscles causes inhalation. Three distinct sets of organs perform respiration — the anterior air sacs (interclavicular, cervicals, and anterior thoracics), the lungs, and the posterior air sacs (posterior thoracics and abdominals). Typically there are nine air sacs within the system; however, that number can range between seven and twelve, depending on the species of bird. Passerines possess seven air sacs, as the clavicular air sacs may interconnect or be fused with the anterior thoracic sacs. During inhalation, environmental air initially enters the bird through the nostrils from where it is heated, humidified, and filtered in the nasal passages and upper parts of the trachea. From there, the air enters the lower trachea and continues to just beyond the syrinx at which point the trachea branches into two primary bronchi, going to the two lungs. The primary bronchi enter the lungs to become the intrapulmonary bronchi, which give off a set of parallel branches called ventrobronchi and, a little further on, an equivalent set of dorsobronchi. The ends of the intrapulmonary bronchi discharge air into the posterior air sacs at the caudal end of the bird. Each pair of dorso-ventrobronchi is connected by a large number of parallel microscopic air capillaries (or parabronchi) where gas exchange occurs. As the bird inhales, tracheal air flows through the intrapulmonary bronchi into the posterior air sacs, as well as into the dorsobronchi (but not into the ventrobronchi whose openings into the intrapulmonary bronchi were previously believed to be tightly closed during inhalation. However, more recent studies have shown that the aerodynamics of the bronchial architecture directs the inhaled air away from the openings of the ventrobronchi, into the continuation of the intrapulmonary bronchus towards the dorsobronchi and posterior air sacs). From the dorsobronchi the air flows through the parabronchi (and therefore the gas exchanger) to the ventrobronchi from where the air can only escape into the expanding anterior air sacs. So, during inhalation, both the posterior and anterior air sacs expand, the posterior air sacs filling with fresh inhaled air, while the anterior air sacs fill with "spent" (oxygen-poor) air that has just passed through the lungs. During exhalation the intrapulmonary bronchi were believed to be tightly constricted between the region where the ventrobronchi branch off and the region where the dorsobronchi branch off. But it is now believed that more intricate aerodynamic features have the same effect. The contracting posterior air sacs can therefore only empty into the dorsobronchi. From there the fresh air from the posterior air sacs flows through the parabronchi (in the same direction as occurred during inhalation) into ventrobronchi. The air passages connecting the ventrobronchi and anterior air sacs to the intrapulmonary bronchi open up during exhalation, thus allowing oxygen-poor air from these two organs to escape via the trachea to the exterior. Oxygenated air therefore flows constantly (during the entire breathing cycle) in a single direction through the parabronchi.
The cross-current respiratory gas exchanger in the lungs of birds. Air is forced from the air sacs unidirectionally (from right to left in the diagram) through the parabronchi. The pulmonary capillaries surround the parabronchi in the manner shown (blood flowing from below the parabronchus to above it in the diagram). Blood or air with a high oxygen content is shown in red; oxygen-poor air or blood is shown in various shades of purple-blue.
The blood flow through the bird lung is at right angles to the flow of
air through the parabronchi, forming a cross-current flow exchange
system (see illustration on the left). The partial pressure of
oxygen in the parabronchi declines along their lengths as O2 diffuses
into the blood. The blood capillaries leaving the exchanger near the
entrance of airflow take up more O2 than do the capillaries leaving
near the exit end of the parabronchi. When the contents of all
capillaries mix, the final partial pressure of oxygen of the mixed
pulmonary venous blood is higher than that of the exhaled air,
but is nevertheless less than half that of the inhaled air, thus
achieving roughly the same systemic arterial blood partial pressure of
oxygen as mammals do with their bellows-type lungs.
The trachea is an area of dead space: the oxygen-poor air it contains
at the end of exhalation is the first air to re-enter the posterior
air sacs and lungs. In comparison to the mammalian respiratory tract,
the dead space volume in a bird is, on average, 4.5 times greater
than it is in mammals of the same size. Birds with long necks
will inevitably have long tracheae, and must therefore take deeper
breaths than mammals do to make allowances for their greater dead
space volumes. In some birds (e.g. the whooper swan, Cygnus cygnus,
the white spoonbill, Platalea leucorodia, the whooping crane, Grus
americana, and the helmeted curassow, Pauxi pauxi) the trachea, which
some cranes can be 1.5 m long, is coiled back and forth
within the body, drastically increasing the dead space
ventilation. The purpose of this extraordinary feature is unknown.
Air passes unidirectionally through the lungs during both exhalation
and inspiration, causing, except for the oxygen-poor dead space air
left in the trachea after exhalation and breathed in at the beginning
of inhalation, little to no mixing of new oxygen-rich air with spent
oxygen-poor air (as occurs in mammalian lungs), changing only (from
oxygen-rich to oxygen-poor) as it moves (unidirectionally) through the
Avian lungs do not have alveoli as mammalian lungs do. Instead they
contain millions of narrow passages known as parabronchi, connecting
the dorsobronchi to the ventrobronchi at either ends of the lungs. Air
flows anteriorly (caudal to cranial) through the parallel parabronchi.
These parabronchi have honeycombed walls. The cells of the honeycomb
are dead-end air vesicles, called atria, which project radially from
the parabronchi. The atria are the site of gas exchange by simple
diffusion. The blood flow around the parabronchi (and their
atria), forms a cross-current gas exchanger (see diagram on the
All species of birds with the exception of the penguin, have a small
region of their lungs devoted to "neopulmonic parabronchi". This
unorganized network of microscopic tubes branches off from the
posterior air sacs, and open haphazardly into both the dorso- and
ventrobronchi, as well as directly into the intrapulmonary bronchi.
Unlike the parabronchi, in which the air moves unidirectionally, the
air flow in the neopulmonic parabronchi is bidirectional. The
neopulmonic parabronchi never make up more than 25% of the total gas
exchange surface of birds.
The syrinx is the sound-producing vocal organ of birds, located at the
base of a bird's trachea. As with the mammalian larynx, sound is
produced by the vibration of air flowing across the organ. The syrinx
enables some species of birds to produce extremely complex
vocalizations, even mimicking human speech. In some songbirds, the
syrinx can produce more than one sound at a time.
The human heart (left) and chicken heart (right) share many similar
characteristics. Avian hearts pump faster than mammalian hearts. Due
to the faster heart rate, the muscles surrounding the ventricles of
the chicken heart are thicker. Both hearts are labeled with the
following parts: 1. Ascending
Birds have a four-chambered heart, in common with mammals, and some reptiles (mainly the crocodilia). This adaptation allows for an efficient nutrient and oxygen transport throughout the body, providing birds with energy to fly and maintain high levels of activity. A ruby-throated hummingbird's heart beats up to 1200 times per minute (about 20 beats per second). Digestive system
Simplified depiction of avian digestive system.
Many birds possess a muscular pouch along the esophagus called a crop.
The crop functions to both soften food and regulate its flow through
the system by storing it temporarily. The size and shape of the crop
is quite variable among the birds. Members of the family Columbidae,
such as pigeons, produce a nutritious crop milk which is fed to their
young by regurgitation. The avian stomach is composed of two organs,
the proventriculus and the gizzard that work together during
digestion. The proventriculus is a rod shaped tube, which is found
between the esophagus and the gizzard, that secretes hydrochloric acid
and pepsinogen into the digestive tract. The acid converts the
inactive pepsinogen into the active proteolytic enzyme, pepsin, which
breaks down certain specific peptide bonds found in proteins, to
produce a set of peptides, which are amino acid chains that are
shorter than the original dietary protein. The gastric juices
(hydrochloric acid and pepsinogen) are mixed with the stomach contents
through the muscular contractions of the gizzard. The gizzard is
composed of four muscular bands that rotate and crush food by shifting
the food from one area to the next within the gizzard. The gizzard of
some species of herbivorous birds, contains small pieces of grit or
stone called gastroliths that are swallowed by the bird to aid in the
grinding process, serving the function of teeth. The use of gizzard
stones is a similarity found between birds and dinosaurs, which left
gastroliths as trace fossils.
The partially digested and pulverized gizzard contents are passed into
the intestine, where pancreatic and intestinal enzymes complete the
digestion of the digestible food. The digestion products are then
absorbed through the intestinal mucosa into the blood. The intestine
ends via the large intestine in the vent or cloaca which serves as the
common exit for renal and intestinal excrements as well as for the
laying of eggs. However, unlike mammals, many birds do not excrete
the bulky portions (roughage) of their undigested food (e.g. feathers,
fur, bone fragments, and seed husks) via the cloaca, but regurgitate
them as food pellets.
There are three general ways in which birds drink: using gravity
itself, sucking, and by using the tongue. Fluid is also obtained from
Most birds are unable to swallow by the "sucking" or "pumping" action
of peristalsis in their esophagus (as humans do), and drink by
repeatedly raising their heads after filling their mouths to allow the
liquid to flow by gravity, a method usually described as "sipping" or
"tipping up". The notable exception is the Columbidae; in fact,
one recognizes the order by the single behavioral characteristic, namely that in drinking the water is pumped up by peristalsis of the esophagus which occurs without exception within the order. The only other group, however, which shows the same behavior, the Pteroclidae, is placed near the doves just by this doubtlessly very old characteristic.
Although this general rule still stands, since that time, observations have been made of a few exceptions in both directions. In addition, specialized nectar feeders like sunbirds (Nectariniidae) and hummingbirds (Trochilidae) drink by using protrusible grooved or trough-like tongues, and parrots (Psittacidae) lap up water. Many seabirds have glands near the eyes that allow them to drink seawater. Excess salt is eliminated from the nostrils. Many desert birds get the water that they need entirely from their food. The elimination of nitrogenous wastes as uric acid reduces the physiological demand for water, as uric acid is not very toxic and thus does not need to be diluted in as much water. Reproductive and urogenital systems
Seen here is a diagram of a female chicken reproduction system. A .Mature ovum, B. Infundibulum, C. Magnum, D. Isthmus, E. Uterus, F. Vagina, G. Cloaca, H. Large intestine, I. rudiment of right oviduct
Male birds have two testes which become hundreds of times larger during the breeding season to produce sperm. The testes in birds are generally asymmetric with most birds having a larger left testis. Female birds in most families have only one functional ovary (the left one), connected to an oviduct — although two ovaries are present in the embryonic stage of each female bird. Some species of birds have two functional ovaries, and the order Apterygiformes always retain both ovaries. Most male birds have no phallus. In the males of species without a phallus, sperm is stored in the seminal glomera within the cloacal protuberance prior to copulation. During copulation, the female moves her tail to the side and the male either mounts the female from behind or in front (as in the stitchbird), or moves very close to her. The cloacae then touch, so that the sperm can enter the female's reproductive tract. This can happen very fast, sometimes in less than half a second. The sperm is stored in the female's sperm storage tubules for a period varying from a week to more than 100 days, depending on the species. Then, eggs will be fertilized individually as they leave the ovaries, before the shell is calcified in the oviduct. After the egg is laid by the female, the embryo continues to develop in the egg outside the female body.
A juvenile laughing gull
Many waterfowl and some other birds, such as the ostrich and turkey,
possess a phallus. This appears to be the primitive condition among
birds, most birds have lost the phallus. The length is thought to
be related to sperm competition in species that usually mate many
times in a breeding season; sperm deposited closer to the ovaries is
more likely to achieve fertilization. The longer and more
complicated phalli tend to occur in waterfowl whose females have
unusual anatomical features of the vagina (such as dead end sacs and
clockwise coils). These vaginal structures may be used to prevent
penetration by the male phallus (which coils counter-clockwise). In
these species, copulation is often violent and female co-operation is
not required; the female ability to prevent fertilization may allow
the female to choose the father for her
offspring. When not copulating, the phallus is
hidden within the proctodeum compartment within the cloaca, just
inside the vent.
After the eggs hatch, parents provide varying degrees of care in terms
of food and protection.
Internal view of the location of bursa of fabricius
The bursa of fabricius, also known as the cloacal bursa, is a lymphoid
organ which aids in the production of
List of terms used in bird topography
^ Ritchison, Gary. "
v t e
Gross anatomy Superficial anatomy Neuroanatomy Comparative anatomy
Bacterial cell structure
Level of organization Structures
Plant anatomy Plant habit Plant life-form/growth-form/physiognomy Plant morphology Fruit anatomy
Body plan Decapod anatomy Gastropod anatomy Insect morphology Spider anatomy
Human anatomy Neanderthal anatomy Cat anatomy Dog anatomy Horse anatomy Elephant anatomy Giraffe anatomy
Allometry Brain morphometry Morphometrics Physiognomy
v t e
Birds (class: Aves)
Origin of birds
Origin of flight
Archaeopteryx Omnivoropterygiformes Confuciusornithiformes Enantiornithes Chaoyangiiformes Patagopterygiformes Ambiortiformes Songlingornithiformes Apsaraviformes Gansuiformes Ichthyornithiformes Hesperornithes Lithornithiformes Dinornithiformes Aepyornithiformes Gastornithiformes
Families and orders Genera Glossary of bird terms List by population Lists by region Recently extinct birds Late Quaternary prehistoric birds Notable birds
swans true geese
Aythyinae Dendrocygninae Merginae Oxyurinae Plectropterinae Stictonettinae Tadorninae Thalassorninae
Galliformes (landfowls- gamebirds)
Cracinae Oreophasinae Penelopinae
Aepypodius Alectura Eulipoa Leipoa Macrocephalon Megapodius Talegalla
Acryllium Agelastes Guttera Numida
Callipepla Colinus Cyrtonyx Dactylortyx Dendrortyx Odontophorus Oreortyx Philortyx Rhynchortyx
Phoenicopteriformes (flamingos) Podicipediformes (grebes)
Cuculiformes (cuckoos) Musophagiformes (turacos) Otidiformes (bustards)
Gaviiformes (loons or divers)