Bird Basics

What makes a bird a bird?

• Bipedal

• Feathers

  • filamentous, soft, flexible, light-weight

• Bills

• Adaptations for flight

  • no teeth

  • gizzard

  • bones—spongy, strutted, hollow

  • keeled sternum for muscle attachment

  • furcula—springy to beat wings

  • fused hand bones to maneuver wings

• Amniotic eggs with calcified shells

• Endothermic and homeothermic

• High metabolism

  • 4-chambered heart and lung plus air sacs

Biogeography

• Present on all continents

• Greatest species richness in the tropics of South America

• Migration

  • many birds live parts of life on different continents

  • implications for monitoring and management

Bird Evolution

• Theropods—dinosaurs that shared many characteristics with birds

  • bipedal

  • hollow bones

  • wishbone

  • 3-toed foot

• Archaeopteryx—150 million years ago

  • Intermediate between reptiles and birds

  • Crow-sized

  • Bipedal

  • Small teeth

  • Feathers on wings and tail

  • Only short flights

  • Enlarged visual and hearing centers in brain

Adaptive Radiation

• Rapid diversification of a lineage

  • Different species adapt to different ecologies and behaviors

• 30 orders

• 193 families

• 2099 genera

• > 9700 species—many more over evolutionary time

Variations

• Used for classification

• Bill size and shape—type of food eaten

• Leg length—perching and locomotion

• Anatomy of feet—habitat and locomotion

• Plumage—behavior, habitat

• Silhouette—locomotion