2o6 POPULAR SCIENCE MONTHLY. 



are the strong lure, the talisman, the magnet to which the parent is 

 irresistibly drawn. The tree, the branch, the nest itself, what are 

 these in comparison with the yoimg for whom only they exist? This 

 is true notwithstanding the fact that birds will sometimes leave their 

 young to perish while they start on their migrations. As a rule they 

 follow one line of conduct until their instinct in this direction has 

 been satisfied. 



With some species it is possil)le to make the necessary change with- 

 out evil consequences when there are eggs in the nest: with others we 

 must wait until the j^oung are from four to nine days old. It is all a 

 question of the strength of the parental instinct, and this varies 

 between wide limits in different species, and very considerably between 

 different individuals. From the nature of the case there can be no 

 infallible rule. If we know little of the habits of the bird in question, 

 it is safest to wait until the seventh to the ninth day after hatching, 

 or when, as in many of the common passerine birds, the feather-shafts 

 of the wing-quills begin to appear, or, better, when they project from 

 one-quarter to one-half inch beyond the feather-tubes. At this period 

 the parental instinct is reaching its maximum, and, what is equally 

 important, the sense of fear has not appeared in the young. 



Young birds from one to five days old as a rule cannot stand exces- 

 sive heat. Even when fed and brooded they will sometimes succumb, 

 and here lies the serious danger to be guarded against. A nest of 

 very young birds well shaded by foliage cannot be safely carried into 

 the direct sunshine of a hot summer's day, hence the importance of 

 beginning operations at the proper time when the weather is suitable, 

 and further of not allowing your enthusiasm to get the better of your 

 judgment. 



The young may be handled or fed as much as one wishes, provided 

 they have not acquired the instinct of fear. If you are uncertain as 

 to this, and your aim is to study the nesting habits, it is better to avoid 

 approaching, touching or in any way disturbing the young after the 

 flight-feathers have appeared. The cutting of leaves or twigs which 

 obstruct the light or cast undesirable shadows should be done before 

 this time. 



Young birds eight or nine days old stand the lieat well, provided 

 they are fed, but on very hot days they should not be allowed to go 

 without food for more than two hours at the longest. Should the 

 parents bring no food during this time, it is better to feed the young 

 in the nest, and to suspend operations until the next day. 



The old birds may be expected to come to the nest in from twenty 

 minutes to an hour, when the tent is brought into use immediately 

 after the removal of the nesting bough. It is naturally impossible to 

 predict exactly what will happen until the experiment is tried, since 



