CONTENTS 



Preface 



Contents 



List of Plates 



List of Drawings in the Text 



I. The Chief Characteristics of Birds . 



Intensity of Life in Birds, i. Running and Parachuting before 

 Flying, 2. Supply of Body with Arterial Blood Exclusively, 3 

 Warm-Bloodedness, 4. Feathers, 5. Adaptations Accessory to 

 Flight, 6. Mentality of Birds, 7. Nesting, 9. Migration, 10. 



II. External Features Biologically Considered 



Shape and Pose, 11. The Skin, 12. Plumage of Birds, i5. 

 Moulting of Feathers, 29. Coloration, 33. 



III. Adaptations of the Bird's Skeleton .... 



Lightness and Tendency to Fusion, 47. Adaptations to Flight, 

 49. Adaptations to Bipedal Progression, 57. Adaptations of 

 the Skull, 62. Adaptations in the Backbone, 66. Muscular 

 System, 6g. 



IV, The Flight of Birds 



Origin of Flight, 71. Movements in Flight, 72. Gliding Flight, 

 75. Ordinary Flight, 77. Sailing Flight, 78. Velocity of 

 Flight, 80. General Biological Significance of Flight, 81. 



PAGE 

 V 



46 



71 



87 



V. Food : its Capture and Utilisation .... 

 Methods of Food-getting, 87. Adaptations of Bills, Tongue, 

 and Feet, 92. The Food-canal and its Annexes, 98. Physio- 

 logical Summary, no. 



VI. The Internal Economy of the Bird's Body . .112 



Tlie Master-Activities, 112. Muscular Activity, 113. Nervous 

 Activity, 115. The Sustentative Functions, 122. Respiration, 

 123. Excretion, 130. The Uses of the Blood, 132. Warm- 

 bloodedness, 136. The Regulatory System and the Resulting 

 Correlation, 137. 



VII. Adaptation to Haunts i44 



Arboreal Life, 144. Aquatic Life, 145. Adaptations to Swamps, 



149. Adaptations to Desert and Steppe, 149, Mountain Birds, 



150. Moorland Birds, 153. Birds of the Sea- Cliffs, 154. 

 Birds in other Haunts, 157. Protective Coloration, 158. 



