HOW TO KNOW THE BIRDS 57 



will help fix it more firmly in the mind. Any of the 

 methods described in Chapter II may be used, or 

 simply a description in words may be given. An- 

 other interesting study is to begin just before sun- 

 rise some morning in May, and note the order in 

 which the different birds begin to sing, and the order 

 in which they leave off as the day progresses. Like- 

 wise the order of beginning and stopping in the late 

 afternoon. 



Nesting-habits. The nesting-season offers oppor- 

 tunity for the closest observation of birds. Many 

 things may be learned which have never before been 

 recorded. Some things that may be observed are 

 the location of the nest, materials used in making it, 

 work done by male and female, length of time re- 

 quired to build, number and color of eggs, time of 

 incubation, number of times young are fed in an 

 hour, kind of food brought, how the work is divided 

 between male and female, time young remain in 

 nest, care of young after leaving nest. 



During the height of the nesting-season, about the 

 middle of June, a list may be made of all the birds 

 seen for a week, which will include those birds that 

 nest in a locality, as by this time the transient visit- 

 ants have departed. 



The United States Bureau of Biological Survey 

 has begun to have annual censuses taken by volun- 

 teer bird-students throughout the United States, so 

 that some definite information may be obtained re- 



