CONTENTS XV 
CHAPTER X. 
BiRD POPULATION : 4. ; os . "204 
CHAPTER XI. 
CoLour, SoNG AND ALLIED PHENOMENA... inet 207 
Nature of colours—Objective colours—Subjective colours— 
Variety of colours in the same bird—Protective coloration. 
—Sexual coloration, song, antics, combats—Theories to 
explain these phenomena—Summary 
CHAPTER XII, 
COLORATION OF Eacs. . 2. wg. ft ke te 321 
CHAPTER XIII. 
INSTINCT AND REASON . e- 3 a ae Bar 
Song—Nest-building—The cuckoo instinct—Piracy—The 
death-feigning instinct— Origin of instincts, 
CHAPTER XIV. 
MIGRATION... .. ae ee Sis sagt 347 
The distances covered—The east and west migration—The 
return route—-Return to the same spot—The time occupied 
in migration—The beam wind theory—Wings shaped for 
long flight—From far south to far north—-The height at 
which migrants fly—Order of departure —Partial migrants 
—The nesting-places of migrants—The cause of migration 
—How migrants find their way—Exceptional migrations 
—Stray wanderers—A note on geographical distribution. 
