204 THE MIGRATIONS OF BIRDS 



species, so that one must scan each individual to 

 make sure that some species new to the day's list 

 of birds is not overlooked. Their identification in 

 spring is not difficult, save as it necessitates memo- 

 rizing the characters that distinguish a large num- 

 ber of forms, as at this season males are in breeding 

 dress and are marked by many beautiful patterns, 

 which include combinations and blendings of five 

 of the colors of the spectrum, blue, green, yellow, 

 orange, and red. With these as a base the diversity 

 of shade of markings and mixture of colors is almost 

 endless. Though well marked in spring, in autumn 

 these same birds are the despair of the beginner in 

 field ornithology, as the young wear soft blended 

 patterns and even the adults have subdued their 

 brilliant colors or have discarded them for others 

 of plainer hue. Particularly astonishing is the 

 change in the chestnut-sided warbler, which in 

 spring has a chestnut line on the sides and a yellow 

 crown-cap and in autumn shows us a greenish back 

 and a white breast, or in the bay-breasted warbler, 

 which exchanges its handsome plumage for a duller 

 streaked dress, in which many individuals can be 

 distinguished from the related black-poll only by 

 the color of the tarsus and feet. Without these 

 active sprites, however, much of the thrill of autumn 

 migration through eastern woodlands would be lack- 

 ing, as their very elusiveness makes our wood warb 

 lers the more attractive. 



