^°*i9l™] General Notes. 257 



Effect of Cold on Moult. — In the American Naturalist for 1908 Mr. 

 C. W. Beebe reported some experiments on male Scarlet Tanagers and 

 Bobolinks to determine the effect of external factors on moult and its se- 

 quence. His birds, confined in the dark, and rather over fed, held their 

 nuptial plumage all summer and winter, and when brought into normal 

 conditions the following spring, moulted from nuptial to nuptial, thus 

 reversing the proper order. 



In 1911 I made an experiment on a male Mallard Duck to determine 

 primarily the effect of cold upon the moult. I chose a Mallard of the toy 

 variety because of its small size. At the same time I took as a control 

 another male toy duck and placed them both in crates of similar sizes, 

 about two and one half by one and one half feet. 



The experiment was begun on April 15, 1911, when of course all Mallards 

 are still in full dress. I was enabled to keep the bird to be experimented 

 upon together with another animal experiment in a special room of the 

 Quincy Cold Storage Plant in Boston, thanks to the kindness of Mr. G. V. 

 Crocker. The room was kept at an even temperature of 25° F. Rarely 

 it got as warm as 30° or as cold as 22°. It was practically dark, though 

 lighted at times by electricity. 



Both the cold room duck and the control duck were fed on the same 

 ration of hard grain. Notes were made of both birds from time to time, 

 and the cold room bird was visited about every ten days. 



The observations in detail are added, but to sum up, the cold room bird 

 kept his winter plumage all summer without shedding a feather and was 

 taken out about November first and placed with the other ducks at Wen- 

 ham. He remained the same all winter and moulted very early in the 

 spring, rapidly assuming eclipse plumage. 



The control duck, likewise closely confined, but out of doors assumed an 

 eclipse plumage, although not a perfect one, and when liberated at the 

 same time as the other bird, took on a delayed and rather imperfect winter 

 dress. Both birds were very fat, but otherwise in perfect health through- 

 out the whole period. 



It is perhaps to be regretted that the control bird was not kept through 

 the summer in the dark, as this would have tended to rule out the light 

 factor. This factor may or may not have had a positive effect. 



It is certain that close confinement alone greatly delayed and rendered 

 less perfect the spring to summer and summer to winter moult in the 

 control bird, but it had no such effect as the cold and dark plus the confine- 

 ment. The sequence of plumage was certainly governed by the season, 

 as no attempt was made on the part of the cold room bird to change his 

 left over winter dress when he was liberated in November. 



The following notes were made at the time. 



April 15, 1911. Experiment started . 



June 24 : The cold room bird showed no moult, breast worn from the bars 

 of the crate, and a small area of skin around both eyes denuded of feathers. 

 Other mallards at Wenham were beginning to moult at this date. 



