EXERCISE 31 AVES I: OBSEWATIONS AND CLASSIFICATION OF SPECIMENS Structure 3 1.1 Introduction 0b.jectives 31.2 Material Required 3 1.3 General Characters of Aves 3 1.4 Observatioll of Museum Specimens Milvlw nligrans B~ll~obzt bo Corvzw splendens Dio.zit.its adsit~zilis Colllnlbin Iivin Ds17dvocopu.s tizehrnttensis Psittnclrka ellpatria Callzls donlssticus Ezluj~nanzysscolol~ncen Stvuthio cnnzellrs 3 1.5 Ter~ninalQuestions 3 INTRODUCTION Birds occupy all co~itinents,oceans and islallds, penetrating tlie Arctic and the Antarctic and live from sea level to above timberline on tlie Everest. Tliey have well adapted migratory habits. They are tlie best known and mosl: easily recognised animals being ~iniquein having feathers for flying wliicli also cover and insulate their bodies and provide them with distinctive colouration. The body weight is reduced for flight by elimination of sonie bones and fusion of others and by presence of some air filled cavities and spaces in Inany bones. High metabolic rate,and raised body temperature,stro~igflight muscles and advanced respiratory ii~cchanismwith air sacs and lungs provide necessaly strength for flight. Tliey 11ave Ilighly developed voice,siglit and hearing but poor sense of s~iielI. Class Aves is made up of 28 orders of living birds and a few fossil orders. More tha~i 9600 species have been named so far and only a few species remain to be discovered. Of the 28 orders, four or five (depending on tlie classificatio~lsystem) are ratiiae or flightless birds, tlie remaining orders are carillate birds with keeled stenium.111this exercise you will observe and classify some representative specimens of class Aves. We would advise you to come prepared for tliis exercise by reading Unit 3 of Block I, LSE-I0 again as you would find it useful to refer to Fig.3.39 of that unit for iclentifying the orders of this class. Objectives After completing illis exercise you will be able to: identify and give scientific and common names of some of the avian species, a classify the identified genera upto the level of order, a list tl~echaracters justifying the classificatioli of the identified specimens and mention special features if any, a mention the liabitat and geographical distribution, draw labeled diagram of each of the identified genera, mention tlie economic i~nporta~iceif any, of each of the given genera. Animal Diversity Lab. 31.2 MATERIAL REQUIRED 1. Stuffed specimens oE: Kite Owl Common crow Drongo Blue rock pigeon Fowl Woodpecker Koel Large Indian parakeet Ostrich 2. Hand lens In absence of stuffed specimens good large sized photographs may be provided. 31.3 GENERAL CHARACTERS OF CLASS AVES Let us recall the general characters that distinguish class Aves from all other classes.' 1. Endothermic tetrapod vertebrates with feathers. 2. Forelimbs modified into wings each bearing three clawless digits and feathers for flight. 3. The hindlimbs are modified for walking, perching or swirmning and bear four toes. 4. No glands in the skin except for oil gland in the tail, 5. Bones are strong fully ossified though light, provided with air cavities. 6. Skull bones fused, bearing single occipital condyle as in reptiles. This m,akes it possible for birds to rotate their heads almost 180'. 7, Modem birds have no teeth, only horny beak present. 8. Pelvis fused to many vertcbrae but open ventrally, small ribs with strengthening processes; sternum is broad, well developed usually with median keel or reduced with no keel; flight muscles attached to keel. 9. The sacral vertebrae are fused with lumber, last thoracic and last caudal vertcbrae to form synsacrum. 10. Posterior caudal vertebrae hsed to form pygostyle. 11, Gullet has crop to store food, muscular gizzard in the stomach to masticate food. 12. Lungs spongy attached to air sacs that extend into various parts of the body. 13. Voice produced by syrinx situated at the junction of the trachea and the bronchioles. 14. Heart four chambered. 31.4 OBSERVATION OF SPECIMENS Look at the given specimens of birds carefully, use the hand lens wherever you need to see any details and note down all the characters. Compare your observations with the characters given in the text as you draw the given specimen. 3 1.4.1 3Milvus migrans Special Characters i) Pariah kite or Milvus is a large bird about 45-60 cm in length. ii) The plumage is reddish brown streaked with dark brown in both the sexes. iii) It is distinguished from all similar bird by its forked tail. iv) The toes are elongated bearing sharp pointed claws for grasping and capturing. v) The beak is sharp pointed and hooked, very well adapted for tearing the flesh of Aves -I: Observations and the prey. Classification of Specimens Habit and Habitat Milvus is largely a scavenger bird feeding on rodent pests, reptiles, small birds, earthworms and garbage etc. It can be seen soaring around villages and towns at all times. Avoiding only dense forests. It boldly swoops down to snatch food from the busiest street or market. k Geographical Distribution Milvus is found throughout India, Pakistan, Bangladesh, Sri Lmka and Myanmar. Classification and its Justification Kingdom Animals, multi-cellular organisms with cells that lack a cell wall, many capable of movement or inovement of some of their body parts or capable of inovement at some time of their life cycle; hetcrotrophic nutrition. Phylum Chordata Dorsal tubular nerve chord; notochord and paired gill slits present. Group Notochord is replaced by vertcbral colurrm; 2 pairs of appendages; circulatory system closed; hepatic portal system prcscnt; RBC present in blood. Class Aves Endothermic with feathers; forelimbs modificd into wings, claws abscnt; hind limbs adapted for climbins perching or swimn~ing;skull with single occipital condyle; beak prcsent; sternum wcH developcd; ainniotic; oviparo~~s. Subclass Tail sl~oi-t,ends in pygostyle; mctcarpal fbsed with distal carpals to foriu carpometacarpals; sternum well developed with keel. Superorder Neognathae Slcull ~lcognatl~us;feathers with interlocking n~echanisnl;wings well developed. Order Falconiformes Beak short and curved at tllc tip; mandibles sharp-edged; feet with sharp curved claws; diurnal strong flier. Genus Milvus Species migrans Conlmon name Pariah Kite 31.4.2 Buho bubo Special Cl~aracters i) Barn owl is a large and robust bird, measuring upto 60cm in length. ii) The colour is dark brown streaked with tawny buff and black. iii) The head is large and has two black ear tufts or horns. iv) The eyes are large, round and directed forwards, v) The legs are fully feathered. Habit and Habitat Barn owl is nocturnal but can be seen frequently during the day time. It spends the day resting on the ground under the sl~elterofa bush or on some shady projection of a rock near a river.Its food co~lsistsof small mammals, birds, lizards, and other reptiles; also feeds on small insects as well as on fish or crabs. Bcst known for its deep double hoot. Animal Diversity Lab. Geographical Distribution Barn owl is found throughout India, Pakistan and Myanmar. Fig. 31.2: Bubo bubo. Economic Importance The barn owl is a farmer's friend, for it kills a large number of crop pests like rodents and other vermin. It deserve the strictest protection. Classification with Justification Kingdom Animalia Animals, multi-cellular organisms with cells that lack a cell wall, many capable of moveinent or movement of some of their body parts or capable of movement at some time of their life cycle; heterotrophic nutrition. Phylum Chordata Dorsal tubular nerve chord; notochord and pl~aryngealgill slits present. Subphylum Vertebrata Notochord is replaced by vertebral column; 2 f pairs of appendages; circulatory system closed; hepatic portal system present; RBC present in blood. Class Aves Endothermic with feathers; forelimbs modified into wings, claws absent; hind limbs adapted for climbing perching or swimming; skull with single occipital condyle; beak present; sternum well developed; amniotic; oviparous. Subclass Neornithes Tail short, ends in pygostyle; metcarpal fused with distal carpals to form carpometacarpals; sternum well developed with keel. Superorder Neognathae Skull neognathus; feathers with interlocking mechanism; wings well developed. Order Strigiformes Eyes large, directed forwards; Aves - I: Observations and Genus Bubo Classification of Specimens Species bubo Conunon name Barn owl Characters I i) l11e adult grows to 32 to 42cni in length. ii) The body is covered with glossy black plumage while the neck and breast are grey. I iii) Both sexes are similar. 1 iv) Tail feathers arc elongated. I i v) Eyes are large, beak elongated with a broad base, gradually tapering. 1 vi) Fect are well adapted for perchirlg, three toes in front and one behind 1 Fig. 31.3: Curvns. splerrde~ts. i 1 I Habit and Habitat t i Onlnivorous and scavengcr in fceding habit as they eat any thing from dead sewer rats i to kitcl~cnrehgc, insects, fiuits, grains, eggs, etc., therefore, is responsible for the i cleanliness of the surroundings. It is almost totally dependent on human presence. It 1 makes a large stick nest placed in a tree and is frequently yarasitised by the koel, P I i Geographical Distribution It is abundantly found throughout the peninsula of India and therefore is the most familiar bird of our towns and villages. Classification with Justification Kingdom Animalia Animals, multi-cellular organisms with cells that lack a cell wall, many capable of movement or movement of some of their body parts or capable of movement at some time of their life cycle; heterotrophic nutrition. Phylum Chordata Dorsal tubular nerve chord; notochord and pharyngeal gill slits presalt. Subphylum Vertebrata Notochord is replaced by vertebral coluinn; 2 pairs of appendages; circulatory system closed; hepatic portal system present; RBC present in blood.