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to breeding and migration; the time of its onset in relation to sex, cli- 
matic conditions, the individuality of the bird, etc., etc. 
“The colors of the eyes, bill, legs, and feet, and also cere, lores, and 
eyelids, which are naked in some species, change frequently in color 
from youth to maturity or with the seasons”, wrote Forbush (’27). 
The color of the lining of the mouth and tongue should be noted, espe- 
cially in young birds. 
In much of this detailed work indoors the significance of the ob- 
servations made depends on recognition of the individual outdoors, and 
also full knowledge of the status of its family affairs. 
Field Study of Birds 
For the field study of birds it is essential to use colored bands. 
The results of much good work in the past have been vitiated by the 
impossibility of absolute identification of the individual bird. Now at 
last We are ready to proceed on sure ground. 
To catalog the different problems under life history studies would 
demand a long treatise. Every bird bander should diligently peruse 
the excellent list at the end of their “Manual” (Lincoln and Baldwin, 
’°29). I shall confine myself to a few suggestions along lines which I 
have found particularly fruitful. 
The question of territory is very much to the fore at present. 
Which birds are true territory holders and which are not? What is 
the purpose of territory? 
The matter of song can be satisfactorily studied only in birds in- 
dividually known. The relation of song to weather, time of year, nest- 
ing cycle, age of the singer—all these are important questions. Little 
has been done on studying the development of song, or the subject of 
the singing of the female. In which species does the male stop sing- 
ing on the arrival of a mate, and when does he begin to sing again? 
There are many important problems connected with the study of 
eggs which can only be answered with birds that are marked. Some 
of these questions concern: the time of beginning to lay; number of 
eggs in a set; number of sets ordinarily laid and greatest number pos- 
sible; color in a set and in different individuals; size of eggs—in dif- 
ferent individuals, in the same set, in succeeding sets, in succeeding 
years; Shape of the eggs, inheritance of color, size and shape. 
How are these phenomena influenced by: 
Factors in the bird herself: age, inheritance, individuality ? 
External factors: increasing and decreasing light, temperature, 
precipitation; food; disturbances of all kinds, in the territory, or 
through Cowbird activities? 
The Literature 
The most fruitful source of suggestions for our own problems lies 
in the well planned, well organized researches of other investigators. 
It is impossible to do the best work without a fair idea of what others 
have done. Yet the task of keeping abreast of the literature of one’s 
