AVES (1).......................................pptx

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1. AVES

2. Aves T heir appendages are modified to wings t he body is covered by feathers BIRDS ARE ENDOTHERM They have high metabolic rate Bones are lightened by numerous air spaces Modern birds possess beaks and lack teeth

3. Evolution of birds from reptiles There is great similarity between birds and reptiles that is why called as glorified reptiles

4. Archeopteryx A vertebrate fossil was found in bivaria , germany n 1861 It lived during jurassic period about 150 myo It has following characteristics It was pegion size animal It had long tailed reptilian It has clawed fingers

5. External structures and locomotion Feathers Plumage: Covering of feather on a bird is called plumage

6. Function of feather Have three primary functions Essential for flight, provide lift, help in steering (turn direction) Prevent excessive heat loss Role in courtship, incubation and water proofing

7. Development of feather Development is similar to epidermal scales of reptiles Inner pulp of feather contain blood vessels Blood provide nutrient for growth Blood supply is cut off in mature feathers Thus feather become dead Feather are embedded in epidermal invaginations of the skin called feather follicle

8. Types of feather Contour feather They cover body wings and tail They consist of shaft Feather barbs are branches of the shaft The barbules are the branches of barbs Barbules of adjacent barbs overlap one another The hook like hamuli lock the barbules Interlocking barbs keep contour feather frim and smooth

9. Down feather Present on skin Insulating feather

10. Filoplumes They are also called as pinfeather They have sensory function

11. Maintenance of feathers Birds maintain clean plumage It removes parasite from feathers and skin Preening Keep feathers clean, smooth, and in place Done by rubbing bills over leather Dislodged humili can be rehooked with help of bills Oil glands present at base of tail of many bird make Plumage water repellent and slimy It prevent chafing (grass particle trapping) Anting: Birds pick ants and rub on thei r skin. Ants produce formic acid and prevent them from mites attack

12. Color pattern in feather Two factors involve in coloration of feathers Feathers pigment These pigment deposit during feather formation Structural colors: Appear due to irregulaties on the surface of feathers These diffract white light and produce colors Iridescence Flattening and twisting of feathers produce coloration

13. Nutrition and digestion Birds feel great appetite High metabolic rate is need for endothermy and flight Eg : Humming birds feed constantly during day and cannot maintain high metabolism at night. Therefore they become torpid at night They reduce temp and respiratory rate. They again become active and feed in morning

14. Bill and tongue Bill and tongue are modified for feeding Eg : woodpecker tongue is barbed, used for extracting grub (larvae of insect) from bark of teeth Humming birds are nectar feeder. They roll tongue to form tube for extracting nectar from flower

15. Crop Is a diverticulum of esophagus It is storage structure It allow birds to quickly ingest large quantity of food Then they move to save places and digest the food Crop of pigeon produce pigeon milk Pigeon milk is a cheesy secretion It is formed by proliferation and sloughing of the lining of the crop Young pigeon feed on pigeon milk till they are able to eat grains Vultures and birds prey also used their esophagus for the storage The insectivores birds feed through out the day Therefore crop is less developed in them

16. Stomach Stomach has two regions Proventriculus 2. Ventriculus /Gizzard Proventriculus : It secrete digestive juices that initiate digestion Ventricules or Gizzard: It has muscular walls to crush the seeds and other hard material. Birds swallow sand and stone in gizzard. These stone help in digestion

17. Intestine Most of digestion and absorption occur in small intestine Intestine receive secretion from the pancreas and liver that help in digestion Paired ceca are present at the union of the large and small intestine Ceca are blind ending sacs They contain bacteria. These bacteria help in digestion of cellulose

18. Migration “The periodic movement of birds between breeding and non breeding areas are called migration” Most migration are annual They have nesting areas in northern region and wintering grounds in south 70 % of earth land is in northern hemisphere Migration allows birds to leave the climatic extreme

19. Stimulus of migration Photoperiod (change of day length) help in development of gonads Increase day length in spring promote development of gonads

20. Mechanism of migration Some birds are long distant migrant They store fats equal to 50% of their body weight They make non stop journey Other species migrate slowly