Classification of Birds | Class Aves

In this article we will discuss about the classification of birds.

1. Subclass Archaeornithes [Gk. Archios = ancient + ornithos = bird] [1 species, Jurassic, Bavaria]:

i) This subclass includes most primitive, fossil birds of Jurassic period and are known from Germany.

ii) Wings had primitive feathers.

iii) Tail feathers were arranged in a row along each side of a long tail.

iv) The tail was long and slender with 21 separate vertebrae.

v) The forelimbs were modified as wings.

vi) The carpals and metacarpals were free. The hand had three clawed digits.

vii) The beak was well-developed. Thirteen pairs of conical socketed teeth were present in the upper jaw and three pairs of similar teeth were present in the lower jaw.

viii) The skull had round cranium and a single occipital condyle.

ix) The zygomatic arch was fairly deve­loped.

x) The parietals were completely fused and inter-parietal foramen was absent.

xi) The inter-orbital septum was slightly developed and the orbit was provided with sclerotic ossicles.

xii) The quadrates were small.

xiii) The mandible was a complex skeletal structure,

xiv) The vertebrae were amphicoelous.

xv) Thoracic ribs were without uncinate pro­cesses.

xvi) The pygostyle was absent.

xvii) The abdominal ribs were present like Sphenodon.

xviii) Flat sternum was devoid of keel.

xix) The pectoral girdle has rudimentary coracoid, distinct T-shaped interclavicle and narrow curved scapula.

xx) The pelvic girdle had large plate-like ilium, having distinct pre- and post acetabular regions. The ischium had a thin foramen. The pubis was narrow, rod­ like and backwardly directed.

xxi) The synsacrum was absent and the sacral region consisted of six vertebrae.

xxii) Humerus was short and stout. The ulna was stronger than radius. The carpals and metacarpals were free excepting the 3rd metacarpal which was fused with carpal.

xxiii) The tibia and fibula were separate and were of equal length. Each foot was made up of tarsometatarsus and four digits.

xxiv) Small and opposable hallux resembled that of modern birds.

xxv) These fossil birds had long, slender and smooth cerebral hemisphere. The cere­bellum was small and placed behind the mid-brain. In spite of this reptilian feature of brain, it is assumed that these birds were warm-blooded.

The subclass includes single genus fossil bird having a single species, Archaeopteryx lithograpthica.

2. Subclass Neornithes [Gk. Neos = modern] (Cretaceous — Recent):

This subclass-includes remaining fossil and living birds.

(i) In most of these birds, the short tail has a terminal pygostyle with semi circularly arranged feathers.

(ii) In most members, the teeth are absent.

(iii) The metacarpals and carpals unite to form carpometacarpus.

(iv) Usually the claws are not present in more than two digits.

(v) Well-developed sternum bears a distinct keel or carina.

The subclass includes two superorders: Odontognathae and Neognathae.

1. Superorder Odontognathae [Gk. Odontos = teeth + gnathos = jaw] Cretaceous birds:

It includes fossil birds which during Cretaceous period flourished to explore the resources of the sea.

i) All the members were flightless and adapted to aquatic life.

ii) All these birds were provided with teeth.

iii) The brain was more like modern birds than the reptiles.

iv) The quadrate was single and basipterygoid process was absent.

v) The pectoral girdle was much reduced and clavicles were not united.

vi) The bones of the pelvic girdle were free posteriorly. They were absolutely flight­less birds.

vii) The forelimb was represented only by humerus.

viii) The strongly built hind limbs were with laterally directed feet having webbed toes.

ix) Presence of a short tail and reduced hand.

The examples are Hesperornis (Fig. 9.38), Baptornis, Neogaeornis and Ichthyornis (Fig. 9.39).

Hesperornis had reduced wings and jaws modified to catch fish. They were divers.

2. Superorder Neognathae [Gk. Neos = modern]:

i) The slender vomer separates the palatines imperfectly.

ii) The palatines are protruded posteriorly to be in contact with the base of the crani­um and remain movably articulated with small pterygoids. This type of jaw arrangement is known as neognathous condition.

iii) Reduced pectoral girdle and no sternal keel (Fig. 9.42).

Some flightless birds such as ostrich, cas­sowary and kiwi are included under this superorder Neognathae recently. Parker and Haswell (1964) and many other zoologists included these ratites or flightless birds under the superorder Palaeognathae for the primitive structure of the palate. But other zoologists like de Beer (1956) have pointed out that the character is not the primitive, may be regar­ded as manifestation of neoteny.

1. Order Tinamiformes (N.L. Tinamus = a genus of tinamou + form) [Tinamus; 47 species]:

i) The birds under this order are found in Southern Mexico, Central and South America.

ii) The size varies from that of Quail to a Partridge.

iii) The tail is absent. When chased, these terrestrial birds run and can fly a short distance.

iv) The keel is present, but the appearance of palate is palaeognathous.

v) These vegetarian birds do not perch and usually use their cryptic colouration for protection.

vi) The eggs have peculiar shining white shell and are incubated by the males.

The order includes a single family Tinamidae having more than forty-five species. The most common species are Crypturellus variegatus (Variegated Tinamon) and Eudromea elegans (Crested Tinamon) and Tinamous (Tinamus).

2. Order Rheiformes (Gk. Rhea = mother of Zeus + form) [Rheas; 2 species]:

i) These birds are found in South America. These running birds live in groups. Food varies from vegetable products to insects.

ii) The height of a male bird is about 165 cm.

iii) Neck is incompletely feathered.

iv) Each hind limb has three clawed toes which are webbed at the base.

v) During breeding season, the males select and segregate with 3-7 females to form a harem.

vi) The nest is dug by the male and all the females lay eggs in the same nest. Nearly fifty eggs are laid in a season and the male incubates them.

vii) Freshly laid eggs are lemon yellow in colour and hatching requires forty days’ incubation.

It includes Rhea americana (Fig. 9.40A) (South American form) and Pteronemia pennata (Damius rhea).

3. Order Struthioniformes (Gk. Struthio = Ostrich + form) [Ostriches; 1 species]:

i) These birds are distributed in Africa and Arabia.

ii) The height is nearly 240 cm and weight is about 136.1 kg. It is considered as the largest living bird.

iii) Feathers are without after shaft.

iv) Wings are small and usually kept folded during running, but may be expanded to work as a brake or steering.

v) Two wing fingers are clawed which are used for defence.

vi) Tail feathers are replaced by long tail coverts.

vii) Hind limbs are strongly built and are not covered by feathers. Only the 3rd and 4th toes are present in the hind limb.

viii) Neck is long and not covered by feathers.

ix) Head is small and flat.

x) The two beaks are more or less round and enclose a broad space.

xi) Prominent eyes have lashes on the upper eyelid.

The order includes ostriches, Struthio camelo (Fig. 9.40B) which is well-adapted to live in desert condition.

4. Order Casuariiformes (N.L.Casuarius = genus of cassowary + form) [Emus and Cassowaries; 5 species]:

i) The birds enjoy distribution in Australia, New Guinea and East India. The order includes two families—Dromaiidae and Casuariidae. The Dromaiidae include common Emu (Dromaeus novaehollandiae) (Fig. 9.40E).

ii) It attains a height of 180 cm.

iii) Neck has incomplete lining of feathers.

iv) Each hind limb is provided with three toes, of which the inner one is built up as a defensive structure.

v) The colouration in both the sexes is deep brown.

vi) All the feathers have after shafts of equal length to the main quill (Fig. 9.41).

vii) Emu is monogamous.

viii) The male digs the nest and sits over the first brood of eggs. The female sits over the second brood.

ix) Number of eggs may be fifteen or more and the eggs are green in colour.

x) The incubation period is 60 days.

The Family Casuariidae includes Casso­wary (Casuarius casuarius) (Fig. 9.40D) which lives a solitary life in the dense tropical forests of Australia, New Guinea and East India. Several species of Cassowary are available and their height may be 135 cm. Feathers look like furs. Stiff and rod-like wing feathers hang over the side of the body.

The head and neck are partly covered by feathers and have bright colouration. In some forms the neck bears identically coloured wattles. In all forms, the head has a horny helmet to help in advancing through dense jungle. The hind limbs are simi­larly built as in Emu.

5. Order Aepyornithiformes:

i) These large, extinct running birds of Madagascar are commonly called ‘Elephant birds’ (Aepyornis).

ii) Some attained the height of 300 cm and their eggs measured 30-5 cm x 24-5 cm.

iii) The wings were small.

iv) The hind limbs having four toes were strongly built.

6. Order Dinornithiformes:

i) It includes fossil and living running birds of New Zealand which are called Moas (Dinornis) (two families having twenty species) and kiwi, Apteryx (Fig. 9.40C).

ii) The size varies widely and some attained the height of 300 cm.

iii) In most Moas, wings, pectoral girdles and keel were absent.

iv) Probably the Moas were vegetarian and possessed short beaks.

v) The feathers were without barbicels.

vi) The kiwis are nocturnal and eat insects, worms and vegetable matters.

vii) The feathers look like hairs.

viii) The beaks are long and pointed.

ix) The eyes are small.

x) The wings are much reduced and the tail is absent.

7. Order Podicipediformes (L. Podea = rump, Pes = foot + form) [Grebes; 21 species]:

The distribution is cosmopolitan. They are aquatic and build nests in floating vegetation. They usually live in freshwater. The legs are placed posteriorly. Only three front toes are webbed by lobed fringing membranes. Reduced tail has degenerated tail feathers. The largest genus is Podiceps (Grebe or Dabclien) and other genera are Aechmophorus (Large western grebe), Podilymbus (Pied-billed grebe) and Centropelara (Short winged grebe).

8. Order Sphenisciformes (Gk. Spheniscus = wedge + form) [Penguins; 17 species]:

i) Penguins, members of the order, are main­ly confined to the southern hemisphere.

ii) The body is perfectly suited for diving and swimming. For this purpose, the body is stream-lined.

iii) The skeleton is solid and air-sacs are absent.

iv) The integument is provided with thick fatty insulating layer and feathers form a compact outer covering.

v) The wings are without feathers and are supported by flat and fused skeletons which are articulated only at the joint of pectoral girdle.

vi) The hind limbs are modified for swimming.

vii) The metatarsals are incompletely fused and toes are webbed. But these limbs are used for walking on the shore.

viii) Food includes fishes, crustaceans and squ­ids. These are gregarious birds and nesting results in a large colony, monogamous in nature and one egg is laid at a time.

iv) Male takes considerable part in incuba­ting and rearing up of the young.

There are 18 penguin species of which only two live exclusively in the Antarctic, Penguins are distributed in Southern part of South America, South Africa, Australia, Galapagos regions and Antarctic regions. The well-known species are Aptenodytes forsteri (Emperor penguin), Aptenodytes patagonica (King penguin), Pygoscelis adeliae (Adelie penguin), Eudyptes crystatus (Rockhopper penguin), Eudyptula minor (Fairy penguin), Eudyptula albosignata (White flippered penguin) and Spheniscus demersus (Jackars penguin).

9. Order Procellariiformes (L. Procellas = tempest + form) [Albatrosses, Shear­waters, Petrels; 115 species]:

All the members are marine and come to land only during breeding season and build nest in holes or crevices in the ground.

i) Hooked bill lies encased within horny plates.

ii) Nostrils are tubular and have well- developed olfactory receptors.

iii) The wings are long in comparison to the size of the body.

iv) Only one egg is laid at a time.

It includes four families and the well- known examples are Albatrosses (Diomedea, (Fig. 9.43) Phoebetria), Shear water (Puffinus), Fulmars (Fulmar), Cape pigeon (Daption), Prions (Pachyptila), Storm petrels (Oceanites), Diving petrels (Pelecanoides).

10. Order Pelecaniformes (G. Pelikan = Pelican + form) [Tropic birds, Boobies, Gannets, Cormorants, Pelican, Frigate birds; 63 species]:

The distribution is cosmopolitan. All are aquatic and fish eaters.

i) Long beaks have wide gap.

ii) Size is usually large and body is adap­ted for diving.

iii) Hind limb has four digits which are completely webbed.

iv) They make nest in a colony and feed the nestlings by regurgitated food.

It includes seven families and well-known examples are: Tropic birds (Phaethon), Peli­cans (Pelecanus), Gannets (Morus), Boobies (Sula), Cormorants (Phalacrocorax), Darter or Anhinga (Anhinga) and Frigate birds (Fregata).

11. Order Ciconiiformes (L. Ciconia = stork 4 form) [Herons, Bitterns, Whale-head stork, Storks, Ibises, Spoonbills; 110 species]:

The distribution is cosmopolitan.

i) All the birds have long, naked legs and long bill.

ii) The legs are adapted for walking on marshes and mudflats.

iii) Four toes are present in each foot, which are webbed only in one family (Phaenicopteridae).

iv) All these birds can fly speedily.

v) The pattern of beak varies but in all, the beak has sharp-cutting edges.

vi) Food capture involves careful obser­vation and speedy striking by the action of mobile neck and beak.

It includes six families and well-known examples are Herons (Ardea, Ardeola, Butorides, Hydranassa), Egrets (Egretta), Bitern (Botaurus, Ixobrychus), Night herons (Gorsachius, Nycticorax, Nyctarassa), Boatbill (Cochlearius), Shoe-bill (Balaeniceps), Hammerhead (Scopus), Storks (Ciconia, Mycteria, Anastomus, Euxenura, Leptoptilos), Jabirus (Fabiru), Spoonbills (Platalea, Ajaia), Ibis (Threskiornis, Eudocimus, Plegadis) and Flamingo (Phoenicopterus).

12. Order Anseriformes (L. Anser = goose + form) [Duck, Geese, swans ; 161 species]:

The distribution is cosmopolitan. Most birds are aquatic but are also capable of flying well. Feeding habit varies from vegetables to fish.

i) Beak is provided with special tactile organ to help in selecting food.

ii) All the toes are webbed.

It includes two families and common examples are Screamers (Anhima), Magfric goose (Anseras), Whistling ducks (Dendrocygna), Swans (Coscoroba, Cygnus), Dabling ducks (Anas), Pochard (Aythya, Netta, Nyroca), Goose (Anser, Branta), Shelducks (Tadorna, Casarca, Alopochen), Perching ducks (Cairina, Dendronsessa), Eider ducks (Somateria, Polysticta), Diving ducks (Mergus, Lophodytes) and Stiff-tailed ducks (Oxyura).

13. Order Falconiformes (L. Falco = falcon + form) [Hawks, Eagles, Secretary-bird, Vultures, Kites, Falcons; 304 species]:

The distribution is widespread throughout the world excepting Antarctica. It includes the birds which are adapted for day-time preda­tory life.

i) Body is strongly built with prominent hook-like beak with cutting edge and the feet are provided with curved, pointed claws in the digits.

ii) The lower beak remains enclosed by the upper beak.

iii) The base of the upper beak bears wart-like variedly coloured protu­berance, called cere, which is pierced by nostrils.

iv) Feathers are stiff and cover the legs excepting the digits.

v) Eyes are laterally placed but power of vision is extremely sharp.

vi) They lead solitary life or live in pairs.

Most birds are monogamous but, before mating, fighting and courtship display occur. Eggs are limited in number and usually one. The incubation is done by female only. The male feeds the female during the act. Nests are made on great heights and in inaccessible places. For a considerable period, the nestlings remain dependent upon the parents.

It includes four families and the well- known examples are Vultures (Sarcogyps, Cymnogyphs, Sarcoramphus, Aegypius, Gyps), Kites (Mileres, Haliastur, Ictinia), Eagles (Aquila, Hieraaetus, Harpia, Haliaetus), Buzzards (Buteo), Harriers (Circus), True hawks (Accipiter), Ospreys (Pandion), Falcons (Falco) and Secretary bird (Sagittarius).

14. Order Galliformes (L. Callus = Cock + form) [Megapodes, Pheasants, Patridges, Quails, Grouse, Turkeys; 183 species]:

The distribution is cosmopolitan. Various types of birds are included in this order, the largest one is 225 cm in length and smallest size is 12-5 cm in length.

i) The head is small but body is compact.

ii) The legs are massive, clawed and used for scratching the soil to search food.

iii) Three toes are anteriorly directed and one is posteriorly directed.

iv) All the birds are terrestrial and usually non-migratory in habit.

v) In most members, the wings are short and round. For this reason these birds cannot fly well, but all are good run­ners.

vi) The beaks are strongly built and arched, most suitable for picking up grains and seeds.

vii) Sexual dimorphism is noted.

viii) Males are aggressive polygamous and do not take part in nest building and maintenance of young’s.

It includes seven families and well-known examples are Megapodes (Leipoa), Curassows (Crax, Mitu, Oreophasis), Grouse (Lagopus, Tetrao, Lyrurus), Partridges (Perdix; Alectoris), Quail (Coturnix), Bobwhite (Colinus), Francolins (Francolinus), True Pheasants (Phasianus, Chrysolophus, Lophura, Callus, Argusianus, Pavo), Guinea fowl (Acryllium, Namida), Turkeys (Melagris) and Hoatzins (Opisthocomus).

15. Order Gruiformes (L. Grus = Crane, + form) [Rails, Cranes, Bustard, Coots, Pinfoot; 1960 species]:

The distribution is cosmopolitan excep­ting polar regions. The members belonging to this order are primarily aquatic but some have settled in grassland and some have become reed-dwellers. They feed usually on vegetable matters. The toes are not webbed. Nests are built on the ground.

This order includes as many as ten fami­lies and well-known examples are Merites (Monias), Buttonquail (Turnix), Plains wande­rer (Pedionomus), Cranes (Grus, Babarica), Limpkin (Aramus), Trumpeters (Prophia), Rails (Rallus), Crakes (Crex), Moorhens (Gallinula), Coot (Fulica), Sungrebe (Heliopais, Heliornis, Podica), Kagu (Rhymochetos), Sunbittern (Eurypyga), Cariamas (Cariama) and Bustards (Otis, Choriotis, Lissotis).

16. Order Charadriiformes (L. Charadrius = Genus of Plovers + form) [Shorebirds, Plovers, Sand Pipers, Gulls, Skuas, Skimmers, Terns, Auks, Puffins, Sand- grouse; 366 species]:

These birds enjoy universal distribution excepting polar regions. This order includes variety of forms which live near water, some live on shore, some on aquatic leaves and some have become aquatic. The feet show various modifications according to habitats.

It includes sixteen families and well-known examples are Jacanas (Metopidius, Hydro- phasianus), Painted snipe (Rostratula, Nycticryphes), Oyster catchers (Haematopus), True plovers (Charadrius, Plyvialis), Lapwings (Vanellus), Woodcock (Scolopax), Snipes (Gallinago, Lymnocryptes), Sandpipers (Calidris, Philomachus, Tringa), Curbus (Numenius), Stilt (Himantopus, Cladorhyncus), Avocet (Recurvirostra), Phaleropes (Phelaropus, Steganopus), Crab-plover (Dromas), Stone- curlew (Burbinus), Pratincoles (Glareola), Courser (Cursorius), Sheathbills (Chionis), Skuas (Stercorarius, Catharacta), Gulls (Larus), Terns (Sterna, Anous), Skimmers (Rynchops), Dovekie (Plautus), Guillemot (Uria), Puffin (Fratercula) and Razorbill (Alca).

17. Order Gaviiformes (L. Gavia = Loon, a bird + form) [Loons; 5 species]:

The birds are distributed in North America, Europe and Arctic region. They are fully adapted for aquatic life and are expert in swimming and diving.

i) The neck is long.

ii) The legs are posteriorly placed and completely encased within skin.

iii) The digits are webbed.

iv) In water only the legs are used for swimming.

v) The bones are not fully pneumatic.

vi) The wings are short and it flies very rarely. But once in air they can fly effectively.

During summer these birds stay in fresh­water but in winter shift to salt-waters. The brightly coloured body has similar pattern in both the sexes except during breeding season. All the wing feathers moult together, for this reason these birds pass through a flightless period.

Due to its inability to move on land, these birds are helpless on land. Eggs are laid in nests among reeds. The well-known examples are Gavia stellata (Red-throated diver loon), Gavia immer (Great northern diver or Common loon) and Gavia adacusi (White-billed Diver or Yellow- billed loon).

18. Order Columbiformes (L. Columbia = a dove + form) [Doves, Pigeons; 310 species]:

The birds under the order are present throughout the world excepting polar regions. All the members are adapted to land life.

i) The size varies from that of a swan to a pigeon.

ii) The head and neck are small and the compact body is supported by small legs.

iii) Each foot has four toes, of which three are forwardly directed and one is backwardly directed.

iv) All the toes lie in the same plane and have small straight claws.

v) The wings are long, pointed and enable the bird to make sustained flight at great speed.

vi) In pigeons and doves, the basal part of the beak has a covering of soft skin which bears longitudinal slit-like nos­trils.

vii) Both the sexes are alike.

viii) They are monogamous but live in groups.

Male takes part in nest building and rear­ing of young’s. Young’s are helpless and nour­ished by ‘pigeon’s milk’ produced by both the sexes during breeding season. Number of eggs ranges from two to three. It includes three families, of which one is extinct (Raphidae). The extinct family includes bird like Dodo.

The living birds which are included under this order are Sandgrouse (Pterocles, Syrrhypta), Rock pigeon (Columba livia), Passenger pigeon (Ectopistes), Turtle dove (Streptopelia), Nicober pigeon (Cabonas), Parrot pigeons (Treron), Crowned pigeons (Coura), Imperial pigeon (Ducula) and Tooth-billed pigeon (Didunculus).

19. Order Cuculiformes (L. Cuculus = Cuckoo + form) [Cuckoos, Hoatzin; 143 species]:

These birds are distributed in the tropical and subtropical regions but concentrated in temperate regions. In all the members, the pattern of digits in the leg is same as that of parrots, but these birds cannot climb. The wings are long and enable these birds to take sustained flight. It includes two families and well-known examples are Turacos, Cuckoos (Cuculus, Chalecites) and Road runner (Geococcyx).

20. Order Psittaciformes (L. Psittacus = Parrot + form) [Parrots; 358 species]:

They are distributed in the tropical region but concentrate in Australia, New Zealand and South America. All the members are specially adapted for arboreal life and can also climb.

i) The beaks are used to help in climb­ing and feet are also used as ‘hand’ to hold the food.

ii) The upper jaw is movably articulated with the cranium.

iii) The first and fourth digits are backwardly directed (Zygodactylous), thus provide better aid to grasp the branch.

iv) The feathers are usually brilliantly coloured. They live in flocks but are strictly monogamous.

The nest is usually built in the hollows of the tree. Young’s are nourished till the attain­ment of maturity. Excepting a few parrots (Geopsittacus) all are diurnal.

The order has a single family and the well- known forms are Macaw (Ara), Amazons (Amazona), Cockatoo (Kakatoe), Parrot (Psittacus), Parakett (Conuropsis), Budgerigar (Melopsittacus), Love birds (Agapornis, Prittacula) and Kea (Nestor).

21. Order Strigiformes (L. Strix = Screech owl + form) [Owls; 186 species]:

They enjoy universal distribution. All these birds are nocturnal and live by hunting small animals (e.g., rodents). Like diurnal birds of prey, beaks and claws are strongly built. The construction of wing feathers is such that they produce noiseless flight.

Detailed examination reveals that outer vane of each outermost wing feather is narrow and constitutes a loose fringe. Such construction, at the time of wing flapping, separates the fast moving and stationary air by a thin slower moving cushion of air.

i) The contour feathers are loosely arranged and extend up to the digits.

ii) Eyes are large and round.

iii) Both the eyes are directed frontally. With the help of neck, it can move its eyes up to 180°.

iv) The retina contains only rod cells and are adapted only to feel low intensity of light.

v) The ear openings are placed on the lateral sides of the head and can be closed at will.

vi) These birds depend more on auditory function than vision during hunting.

It includes two families and well-known examples are common Barn owl (Tyto), Eagle owl (Bubo), Long-eared owl (Asio), Scops owl (Otus), Little owl (Athene), Pygmy owl (Glaucidium), Burrowing owl (Speotyto), Wood owl (Strix) and Snowy owl (Nyctea).

22. Order Caprimulgiformes (L. Caprimulgus = goat sucker + form) [Night jars, Frogmouths ; 105 species]:

The distribution is tropical, subtropical and temperate zones. It includes nocturnal birds which hunt insects and other small animals during twilight. The opening of mouth is broad and the lining has specialised sensory receptors.

The arrangement of feathers is like that of owl and they are silent-fliers. The colouration is pro­tective and helps the bird to conceal easily. It includes five families and well-known examples are Frogmouths (Podargus), Wood- nightjars (Nyctibius), and Nightjars (Capri­mulgus, Nyctidramus, Chordeiles).

23. Order Apodiformes (Gk. Opous = footless + form) [Swifts, Humming birds; 422 species]:

The members of this order are called the swifts and humming birds. The swifts are seen throughout the world but humming birds are seen only in Central America. These birds have short legs and long wings. They can fly very swiftly. They are usually insect-feeders, but humming birds take nectar. In swifts the mouth is broad and eyes are large. In hum­ming birds, the tongue is protrusible and wings can perform hovering movement.

The order includes three families which include well-known examples like Swifts (Apus, Chaetura), Crested swifts (Cypsiurus) and Humming birds (Archilochus, Selasphorous, Patagona, Mellisuga, Loddigeria). The smallest living bird is bee humming bird.

24. Order Coliiformes (Gk. Colius = Genus of the mouse bird + form) [Mouse bird]:

They are restricted in Southern Africa. The size is small (27-5 to 35’0 cm). The legs are short and the digits have sharp curved claws. The hallux or outer toe is reversible and can be brought forward to help in cree­ping on trees. Around the nostrils the base of the bill is fleshy. The feathers are soft and look like hairs. Usually a crest is present on the head. They always remain in a group of twenty or thirty. It includes a single family Coliidae and the example is mouse-bird (Colius).

25. Order Trogoniformes (Gk. Trogon = gnawing + form) [Trogons; 39 species]:

They are distributed in Asia, Africa and tropical parts of America. The foot has pecu­liar arrangement of toes, the first and second are directed backwards and the third and fourth are anteriorly directed. They lead a soli­tary life in dense forest and capture insects in the early morning and during twilight.

The feathers are soft and flight is noiseless. Small and strongly built bill has bristle like feathers in its base. The tip of the beak is hook-like and, in some cases, it is denticulated. Long and stiff tail supports against vertical surface at the time of digging.

It includes a single family Trogonidae and well-known examples are Trogons (Harpac- tes, Haplodermes, Trogon, Calures) and Quatjal (Pharomechrus).

26. Order Coraciiformes (L. Corax = raven + form) [Kingfishers, Bee eaters, Rollers, Hoopoes, Hornbills; 218 species]:

The distribution is cosmopolitan, specially in the tropical climates. The members belong­ing to this group exhibit varied structures.

i) In most members the wings and legs are short.

ii) The beak is long.

iii) The body is brightly coloured and nests are built up as holes in the trees.

iv) In some forms, a few anteriorly direc­ted toes are fused (Syndactylous) and, in others, one of the toes is reversed (Zygodactylous).

It includes nine families and well-known examples are Kingfishers (Alcedo, Ispidina, Dacelo, Tanysiptera, Halcyon, Chlorocerle, Ceryle), Todies, Motmots, Bee-eaters (Merops), Cuckoo-roller, Rollers (Coracias), Ground rollers, Hoopers (Upupa), Wood hoopers and Hornbills (Bucerosjockus, Anthracoceros).

27. Order Piciformes (L. Picus = a Woodpecker + form) [Barbets, ‘ioney guides, Toucans, Wood peckers; 355 species]:

They are distributed throughout the world excepting Australia and polar regions. The most important character is the occurrence of zygodactylous feet, second and third toes are directed forward and the first and fourth are pointed backwards. Usually insectivorous but some forms may be vegetarian. Most members prepare nest in holes but one family (Indi-catoridae) lays eggs in the nests of other birds.

This order includes six families and the well-known examples are Jucamars, Puff birds (Notharcus), Barbets (Megalaima), Honey-guide (Indicator), Toucans (Ramphastos) and Woodpeckers (Dinopium, Picus, Picoides), Dendrocopos (Sphyrapicus, Melanerpes, Fynx).

28. Order Passeriformes (L. Passer = a spar-J row + form) [Broad Bills, Pittas, Larks, Crows, Thrushes, Nuthatches, Sparrows Finches, Swallows, Shrikes, Bulbuls, Cuckoo, Wood-warblers, Fly catchers, Wrens; about 6,500 species]:

They enjoy worldwide distribution. This is the largest order, which includes 5,100 known species. All are collectively known as Perching birds or Passerines. Adapted to vari­ous habitats, they practise various modes of feeding. All are adapted to land life and, in all, the four digits are present at the same level. Nestlings are hatched, only with a few feather tracts and are helpless at the beginning.

This order is subdivided into four subor­ders: Eurylaemi, Tyranni, Menurae and Oscines. All these suborders include sixty-five families. Familiar examples are Broadbills (Calyptomena, Eurylaimus), Woodhewer (Xiphorhynchus), Ovenbirds (Furnarius), Tapaculos (Teledromas), Pittas (Pitta), Asities (Philepitta), New Zealand wrens (Xenicus, Acanthisitta), Flycatchers (Muscivora, Tyrannus Myiarchus, Sayornis, Empidonax, Contopus), Sharpbills (Oxyruncus), Manakins (Chiroxiphia), Chatterers (Cephatopterus, Chasmorhyncus), Lyre-birds (Menura), Scrubbirds (Atrichornis), Larks (Alauda, Lullula, Calandrella, Galerida), Swallows (Hirundo, Petrochelidon, Riparia, Delichon, Cecropis), Pipits (Anthus), Wagtails (Motacilla), Cuckooshrikes (Coracina, Campephaga), Minivet (Pericrocotus), Bulbul (Pycnonotus), Fairy bluebirds (Irena), lora (Aegithina), Leafbird (Chloropsis), Shrikes (Lanius, Prionops), Vanga-shrikes (Euryceros), Waxwings (Bombycilla, Hypocolius), Palm chat (Dulus), Dipper (Cinclus), Wrens (Troglodytes), Mockingbirds (Mimus), Cat-birds (Dumetella), Thrashers (Texestoma), Babblers (Alcippe, Chrysomma, Rhinomvias, Turdoides, Eupetes), Bald crows (Picarthartes), Wren-tit (Chamaea), Old World flycatchers (Muscicapa, Terpsiphone, Rhipidura), True Warblers (Sylvia, Phylloscopus), Wren-thrush (Zeledonia), Blackbird (Turdus), Rock-thrush (Monticola), Nightingale (Luscinia), Shyama (Kittacincla), Fork-tail (Exicurus), Wheat-ear (Oenanthe), Titmice (Parus), Tree-creeper (Certhia), Wall- creeper (Tichodroma), Nuthatch (Sitta, Hypositta), Australian treecreeper (Climacteris), Flower-peckers (Anaimos, Dicaeum), Sunbirds (Aethopyga, Nectarinia), White-eyes (Zosterops), Honey-eaters (Prosthemadera, Moho), Buntings (Emberiza), Cardinal (Richmondena), Tanagers (Piranga), Plus-capped finch (Catambly-rynchus), Swallow-tanager (Tersina), Wood-warblers (Mnotilta, Dendroica), Vireos (Vireo), American blackbird (Quiscalas, Euphagas), Orioles (Icterus), Meadowlark (Starnella), Cow-bird (Molothrus), Finches (Fringilla, Cocco- thraustes, Loxia, Carduelis), House-sparrow (Passer), Weaver-birds (Ploceus), Starlings (Sturnus), Old world Orioles (Oriolus), Drongo (Chaetorhyncus, Dicrurus), Wattled-crow (Calleas), Huia (Heteralocha), Magpie-larks (Grallina, Struthidea, Corcorax), Wood-swal­lows (Artamus), Bell-magpie (Gymnorhina), Piping-crows (Strepera), Butcher-birds (Cracticus), Birds of Paradise (Paradisea), Crow (Corvus) and Magpie (Pica, Cissa).

Indian Species:

The total number of bird species inhabi­ting the earth is about 8600. The subspecies of the bird species is about 30000 (Salim Ali, 1996). Out of 8600 known bird species all over the world, 1 230 species have been recorded from India. These 1230 species fall under 27 living orders. In India, only 20 orders of birds have been recorded. These 20 orders include 78 families.

The rarest birds in India at present are the Mountain Quail, Ophrysia superciliosa (G.E. Gray, 1846), Jerdon’s Courser, Cursorius bitorquatus (Blyth, 1848) and the Pinkheaded Duck (Rhodonessa caryophyllacea (Latham, 1 790). Out of the three, the first has not been met since 1876, the second since 1900 but was rediscovered in 1986 by Dr. Bharat Bhusan, a scientist of Bombay Natural History Society, in Lankamalai Sanctuary of Andhra Pradesh and the third has become extinct. The last specimen, Pink-headed Duck, was recorded by C.M. Inglis in 1935 from Dharbhanga District (Bihar). In captivity it survived till 1945 (Salim Ali, 1960). Sometimes some reports about Pink-headed Duck are being confused with Red-crested Pochard {Netta rufina)

The National bird of India is Peacock:

(Pavo cristatus). It is common in northern, north-western and central parts of India. It was unknown from the eastern part of our country especially from the Gangetic plains. In 1985, a wild population of Indian Peafowl was reported from Rajarhat areas (3 km south of Bandel Station of Hooghly District, West Bengal). Sexual dimorphism of Peafowl is well-marked.

The cock ranges about a length of 1 -80 m, of which the tail is about 1 -20 m in length. On the head there is a tuft of 24 golden-tipped feathers. Cock is excellently beautiful coloured. Hen is dull coloured without huge tail coverts. Males spread their tail feathers and dance when they are happy.

The best singing bird in India is Greywinged Black Bird (Turdus merula) of the Himalayas. It is found in the wooded hills areas up to 1500 m elevation. Other example may be Shyama (Copsychus malabaricus). It is found in the forested tracts of India includ­ing Andaman Islands.

The best talker bird in India is Hill Myna (Cracula religiosa). It has three races and is found in three different areas of India including Andaman Islands. The different areas are (i) Himalayan foothills extending from Almora to Assam; (ii) Orissa, Chhota Nagpur and South- East Madhya Pradesh and (iii) Western Ghats and in Andaman Islands. The other varieties are large Indian Parakeet (Psittacula eupatria) and Roseringed Parakeet (Psittacula krameri).

The smallest Indian bird is Tickell’s Flowerpecker (Dicaeum erythrorhynchos). It is found in mango orchards throughout India except arid region. It is not bigger than a nor­mal thumb.

The largest Indian bird is Sarus Crane (Crus anti-gone). It is about 1 -20-1 -50m in height. It is found in Central and Northern India. Another bird may be considered as Himalayan Bearded Vulture (Gypoetus barbatus). Its wing span is about 2-7 m. They are found in Kashmir, Garhwal, Sikkim and Nepal.

It is difficult to give the position to a sin­gle species as the most beautiful Indian bird. Though a large number of birds of different families claim brilliancy for their different colours in the plumage — male pheasants, as a whole — attract best for the glistening of the plumage.

Some Indian birds are becoming rare and are considered as threatened. They are (i) The White Winged Wood Duck, Cairina scutulata (S. Muller, 1842), is found in Assam and was common in the early part of 20th century. At present it is very rarely seen (ii) The Great Indian Bustard Choriotis nigriceps (Vigor’s, 1831) was an inhabitant of Maharashtra, Gujarat, Punjab, Rajasthan, M.P., A.P., Orissa,

W. Bengal, U.P. and also the Malabar Coast. They like arid and semiarid tracts of India. At present the species has increased its number for the refuge in different sanctuaries and National Parks. Desert National Park (Rajasthan), Velavadar National Park, Bhavnagar (Gujarat), Ahmednagar (Maharashtra)I and Rennibennur Blackbuck Sanctuary (Karnataka) are providing suitable refuge to the Great Indian Bustard, (iii) The Bengal Florican, Eupodotis bengalensis (Gmelin), was common in Northern part of West Bengal, Terai of U.P., Northern Bihar, the Brahmaputra valley of Assam and Arunachal Pradesh. At present stray reports in these parts reveal about 300 birds (Mukherjee, A. K. 1986).

Some birds such as Mauritian dodo, Raphus cuculhatus, the North American passenger pigeon, Ectopistes migratorius have become extinct recently by man.