ARTIFICIAL COLOURING OF BIRDS 271 



present only in their infancy, but seem to promise results of 

 exceptional interest. 



During a recent summer Mr. Beebe put under careful 

 observation several male specimens of the scarlet tanager 

 (Piranga erythromelas) and the bobolink [Dolichonyx oryzivorus), 

 which had not been allowed to breed, and were therefore, 

 despite the fact that it was somewhat late in the season, in full 

 breeding-livery, as well as in the height of vocal and physical 

 condition. In the course of a few days the supply of light was 

 gradually cut off, while the amount of food given to each bird 

 was slightly increased ; and a month later, when under normal 

 circumstances the breeding-dress should have been exchanged 

 for the duller winter garb, no change of any kind took place in 

 the plumage, not a feather being shed. In fact, the birds entirely 

 skipped the autumnal moult, without any apparent effect on 

 their well-being, so far as appearance went, all being in perfect 

 health, although showing symptoms of inactivity owing to their 

 abnormal fatness. 



Occasionally one of the birds was brought into the light and 

 a few mealworms added to its diet, when it invariably resumed 

 its song, so that the spring-notes of the tanager were heard even 

 in mid-winter. This portion of the experiment could not, how- 

 ever, be indefinitely repeated, for the period of song seemed, as 

 under normal conditions, to be definitely limited. 



Early in the following spring some of both tanagers and 

 bobolinks were gradually brought under normal conditions and 

 activities, with the result that the spring moult speedily took 

 place. In the case of the tanagers, the old scarlet and black 

 feathers were replaced by new ones of the same colour, while 

 in like manner the bobolinks moulted into a livery of buff, 

 cream, and black. In fact, the moult was without exception 

 from the breeding to the breeding-livery, and not from the 

 brilliant nuptial to the dull winter plumage. > ^-_ 



11 I think," concludes Mr. Beebe, " we thus have proof that 

 the sequence of plumage in these birds is not in any way pre- 

 destined through inheritance bringing about an unchangeable 

 succession, in the case of the tanager, of green, scarlet, green, 

 year after year, but that it may be interrupted by certain 

 external factors in the environmental complex. J 



" The further significance of these results I leave to others, 

 or until I have more complete data, checked by results derived 



