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 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