This document classifies birds into 23 orders based on their physical adaptations and characteristics. The main adaptations for flight include feathered wings, an endothermic metabolism, a flexible neck, fused vertebrae, and lightened bones. Orders are distinguished by traits such as being flightless, having flippers or degenerate wings, different bill and foot structures, and adaptations for swimming, diving, or perching. The largest order is Passeriformes, which contains over half of all bird species.

1. CLASSIFICATION OF BIRDS
Class Aves
Adaptation for flight include: forelimbs are modified as feathered wings,
endothermic, high metabolic rate, flexible neck, fused posterior vertebrae,
and bones lightened by numerous air spaces. The skull is lightened by a
reduction in bone. Presence of a horny bill that lacks teeth.
1. Order Sphenisciformes: Heavy bodied; flightless, flipper like wings for
swimming ; well insulated with fat. Penguins.

2. Order Struthioniformes & Rheiformes
2. Order Struthioniformes: Large, flightless birds ; wings with numerous fluffy
plumes.
3. Order Rheiformes: Large, flightless birds; degenerate wings with soft loose
plumes- Rheas

3. Order Casuariformes & Gaviiformes
4. Order Casuariformes: Reduced wings: coarse and hair like plumage.
Cassowaries emus.
5. Order Gaviiformes: Strong, straight bill: diving adaptations include legs far
back on body, bladelike tarsus, webbed feet and heavy bones. Loons.

4. Order Podicipediformes & Procellariiformes
6. Order Podicipediformes: Short wings; soft and dense plumage; feet
webbed with flattened nails. Grebes.
7. Order Procellariiformes: Tubular nostrils, large nasal glands; long and
narrow wings. Albatrosses, shearwaters, petrels.

5. Order Pelecaniformes & Ciconiiformes
8. Order Pelecaniformes: Four toes joined in common web; nostrils
rudimentary or absent; large gular sac. Pelicans, boobies, frigate-birds.
9. Order Ciconiiformes: Long neck, often folded in flight; long-legged waders.
Remus

6. Order Anseriformes & Falconiformcs
10. Order Anseriformes: South American screamers ducks, geese and swans,
the latter three groups possess a wide, flat bill and an undercoat of dense
down, webbed feet
11. Order Falconiformcs: Strong, hooked beak ; large wings; raptorial fret.
Vultures secretary birds, hawks, eagles, osprey.

7. Order Galliformes & Cruiformes
12. Order Galliformes: Short beak; short concave wings; strong feet and
claws.Curassows, grouse, quail, pheasants, turkeys.
13. Order Cruiformes: Order characteristics variable and not diagnostic.
Marsh birds including cranes, limpkins, rails, coot

8. Order Charadriiformes & Columbiformes
14. Order Charadriiformes: Order characteristics variable. Shorebirds, gulls,
terns, auks.
15. Order Columbiformes: Dense leathers loosely thin skin; well developed
crop. Pigeons, doves, sand grouse.

9. Order Psittaciformes & Cuculiformes
16. Order Psittaciformes: Maxilla hinged to skull; thick tongue; reversible
fourth toe; usually brightly. Parrot, lanes, macaws.
17. Order Cuculiformes: Reversible fourth toe; soft, tender skin; roadrunners
cuckoos

10. Order Strigiformes & Caprimulgiformes
18. Order Strigiformes: Large head with fixed eyes directed forward; raptorial
foot Owls.
19. Order Caprimulgiformes: Owl-like head and plumage. but weak bill and
feet: insectivorous. Whippoorwills. other goatsuckers.

11. Order Apodiformes & Coraciiformes
20. Order Apodiformes: Long wings; weak feet, Swifts, humming birds. .
21. Order Coraciiformes: Large head; large beak; metallic plumage;
Kingfishers, toddies, bee eaters, rollers.

12. Order Piciformes & Passeriformes
22. Order Piciformes: Long strong beak; strong legs and feet with fourth toe
permanently reversed in woodpeckers. Woodpeckers toucans, honey guides,
barber.
23. Order Passeriformes: Largest avian order; 69 families of perching bids;
perching foot; variable external features. Shallows, larks, crows, titmice,
nuthatches and many others

13. BIRDS