Introduction to the Birds
Class = Aves
 ≈ 9600 species, 27 orders, far outnumber all other
vertebrates except: fishes
 Distribution = worldwide
 Ratites = flightless birds, 4 orders
 Carinate = birds that fly , 23 orders
 Single unique feature of birds = feathers
 Forelimbs modified into wings
 Hindlimbs adapted for walking, swimming, or perching
 All have horny beaks
 All lay eggs
 Most have body adapted for flight (mode of locomotion)
Characteristics
1. Body - head, neck, trunk, & tail
2. Paired forelimbs - modified into wings for flight
3. Epidermis
 Feathers on body, scales on legs
 Down – Insulation
 Molting – loss of feathers
 Water birds molt all feathers @ once
4. Skeleton
 Fully ossified w/ air cavities (reduce weight for flight)
 Beak w/o teeth
 Sternum (breastbone) w/ or w/o keel (for attachment
of flight muscles)
5. Nervous system – well developed
 Sight – excellent
 Hearing – bird song, courtship
 Smell - limited
6. Heart – 4 chambers
7. Endothermic = “heat from w/in” = warm-blooded
8. Respiration – expandable lungs
- Air sacs throughout body
- Permit steady delivery of O2 to tissues
- Reduce weight of body for better flight
9. Syrinx = voice box for vocalizations
10.
Kidneys, no bladder – semisolid excreta
11.
Reproduction
- Oviparous
- Internal fertilization
- Egg incubation external
- Nest building
- Parental care