CONTENTS 
Page 
1 
Introduction 
Buteo borealis, Red-tailed Hawk ^ 
Bibliography 11 
Illustrations 
Plate I. Central tail feathers ^ 
II. Buteo borealis krideri and Buteo borealis calurus 19 
III. Buteo borealis calurus and Buteo borealis harlani 21 
Figure 1. Generalized breeding distribution of forms of Buteo borealis in Canada 
Frontispiece 
41964—2 
