^''..uVN BaiitaTOLD, A Study of tk< Ho;,, Finch. ()3 



Beemed to recover fully on being warmed and sheltered. It was put 

 into another nest, the young of which were of almost identical 

 age with it, in the hope that it might be adopted and fed by the 

 old birds of the second nest. They, however, paid absolutely no 

 attention to it and it perished. The young ol* the year are often, 

 by September, distinctly reddish on head and throat and if we as- 

 sume such birds to have been hatched in the previous April, it 

 becomes apparent that this secondary sexual character appears 

 within the first six months of life. 



Special Detail Study. 



Comparative physiology is of interest and importance both to 

 the biologist and to the zoologist. With a desire to furnish data to 

 both, and in the end that some light might be shed on the nutri- 

 tional processes of developing young birds in a wild state, a scheme 

 of weighing young House Finches from day to day was undertaken 

 by the writer. There are in the literature of ornithology records 

 on the weight of young birds, the daily gain in weight of such young 

 birds, and the amount of food consumed by them — facts apper- 

 taining especially to young Robins in captivity; but there are no 

 such facts known to the writer relating to free wild birds. In order 

 to learn something concerning the weight of a fresh laid egg, the 

 Weight of its embryo on hatching, the daily gain in weight of a 

 nestling, the weight of the same bird on leaving its nest, and, 

 finally, the weight of an adult bird of the same species, the writer 

 carried out an interesting study bearing on these points. 



With House Finches nesting in boxes, as described above, it is 

 extremely easy to take a nest once a day, into one's house, and 

 examine or weigh the eggs or young, without in the least interfering 

 with the regular process of incubation or feeding. 



In order to identify each bird in a particular nest, each one 

 \\;i .narked somewhat as follows: — by using analine dyes dis- 

 solved in alcohol such birds could be colored in areas, on parts, and 

 with such colors, as one desired; for red, fuchsin, and for blue, 

 methylene blue was used. These dyes are readily soluble in alcohol, 

 which quickly evaporates when applied to the young bird, and does 



