Chapter 21-Birds

1. Chapter 21-Birds

2. Class Aves • Birds members of class Aves • Major characteristics of this group: • Adaptations for flight: • Wings • Feathers • Endothermy • High metabolic rate • Vertebral column modified for flight • Other adaptations: • Horny bill • Lack teeth

3. Class Aves • Striking similarities between reptiles & birds, such as: • Single occipital condyle on the skull • Single ear ossicle • Low jaw structure • Behavioral characteristics: nesting & care for young • Birds are thought to share lineage w/ dinosaurs & crocodilians • Distinguishing btwn Orders of birds is based on: • Characteristic behaviors • Songs • Anatomical differences • Ecological niches

4. Evolution of Flight • Oldest Birds: • Archaeopteryx-Jurassic period-150 mya • Has well developed wishbone structure • Glider capable of flapping flight over short distances • Sinornis-135 mya • Characteristics similar to modern birds: • Shortened body & tail • Sternum w/ lrg surface area for flight muscles • Claws reduced • Modified wings to fold while @ rest • Eoalulavis-115 mya • Had alula-wing structure

5. External Structure & Locomotion • Feathers provide (2) essential fxns for flight: • Form flight surfaces that provide lift & aid in steering • Prevent excessive heat loss • Feathers also imp in courtship, incubations & waterproofing • 3 types of feathers: • Contour feathers-cover tail, wing, & body • Down feathers-insulating feathers • Filoplume feathers-sensory function • Why birds maintain plumage: • To rid skin & feathers of parasites • How birds maintain plumage: • Preening • Secretion from oil glands • Anting • Feather pigments deposited during feather formation produce most colors in bird’s plumage • Know why birds go through the molting process

7. The Skeleton • Bird bones are lightweight yet strong • Some bones have air spaces & internal strutting to increase strength