274 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1924 



not have been out of the shell over three or four days, feebly raising 

 their fluffy heads above their warm bed of straw ; we could only see 

 that they were well coated with grayish white down, and that their 

 bills were large and by contrast very black. Close to the young and 

 half buried in the straw lay the carcass of some animal which we 

 could not identify, but from the deep red color of the flesh we 

 suspected that it might be a rodent. 



Although this eagle, as Audubon found by climbing repeatedly to 

 the nest, may sit for a number of days before laying is actually 

 begun, the incubation period could not have been far from four 

 weeks, or approximately from March 20 to April 17. Since eaglet 

 number one left its nest for the first time on June 27, and eaglet 

 number two on July 1, they remained continuously in the aerie about 

 71 and 74 days, respectively. 



IV 



The Vermilion eagles appear to leave their habitual breeding and 

 hunting grounds only when the usual food supplies give out. In 

 ordinary seasons, according to Mr, and Mrs. Buehring, they are 

 away only from six to eight weeks, or from mid-November to mid- 

 January ; but in the season of 1921-22, which was one of the mildest 

 on record, they were missed for barely a fortnight in the latter part 

 of December. In the winter of 1922-23, which continued rather mild 

 until January, both birds remained in the neighborhood, and were 

 even seen resting on the nest itself at the very end of December.* 

 That the use of the aerie as resting place and lookout point, by force 

 of habit, long outlasts the season of young, we know ; by the same 

 token we might expect the adult eagles to form a strong attachment 

 to their home territory, and it may well be doubted if they ever 

 leave it except under the pressure of necessity ; but in this as in most 

 other respects we should expect to find much individual variation, 

 for in a bird of so great a range which covers the entire continent, 

 the pressure referred to must be exerted in greatly varying degrees. 



The young of most birds, when once out of their nest, are, as we 

 say, " out for good." The slender thread, which binds them to 

 their cradle, is snapped at the moment of flight; for all such the 

 nest has suddenly lost its meaning or at least its function, and new 

 habits at once step in to dominate their after life; moreover, it is 

 the young, and not the nest, which is the strong magnet to which 

 the parents are drawn. With the eagle, in this respect also, the 

 case is somewhat diflferent, for its young after their first flight 

 are prone to return to their nest, and this they continue to do for a 

 number of weeks, or for as long as they remain in the neighborhood. 

 The adoption of a nest perch by old and young, as noticed at the 



» As I was informed by Mrs. F. E. Ranney. 



