12 2 Chadbourne on Individual Dtchromatism. lo"^ 



the cage had been placed. These ' tid-bits ' were the cause of 

 much trouble, and after the first trial I never put a mouse in 

 the cage unless there was a second mouse for the other Owl, as a 

 dangerous fight was sure to be the result. By day their sight was 

 as keen as at dusk, but the birds were more restless after dark, 

 though it was necessary to watch closely to prevent them from 

 slipping out while the door of the cage was opened to give them 

 daily food, and I doubt if a movement of any kind was often 

 made that their sharp eyes did not notice. Like all ' Scops ' they 

 were quickly tamed, and quite gentle unless frightened. Twice 

 I heard the tremulous whou-hou-hou-hou-hou note, each time just 

 after dusk when all was quiet and when no gas was lighted. Spit- 

 ting, and a scolding rattle when disturbed, were the only other 

 sounds that they were heard to utter. The ' pellets ' were unlike 

 those found near the familiar ' owl-holes ' and looked like 

 uncooked sausage-meat minus the fat. No gravel was ever 

 found in these castings, yet though more friable than those of 

 the wild birds, they were always firm, well formed, and seemingly 

 held together by a sticky coating that soon dried and looked like 

 gelatine. 



Toward the last of November, nearly three weeks after arrival, 

 the larger, and, as it proved, the female Owl, grew more and more 

 red-brown in tint, until there was little pure gray to be found. 

 This was followed by a constantly increasing amount of tawny 

 red ; while simultaneously the brownish tinge spread over the 

 upper parts and tail-feathers, and the dark cross bars on the 

 breast seemed to fade. The difference was so marked as to be 

 spoken of by five different persons, who had seen the birds at 

 first. Meanwhile the smaller Owl remained unchanged, so far as 

 could be seen, although in the same cage and apparently under 

 the same conditions as the other. 



From the first I searched the cage daily for cast-off feathers, as I 

 wanted to know the number lost when the birds were not molting. 

 During the three weeks and two days only twenty-four feathers 

 were found ; 15 of the ' first plumage ', 3 tail-feathers and 6 mature 

 feathers, or at least not those of the first plumage. The twelve or 

 even twenty-four new feathers, which had doubtless replaced 

 those lost, were evidently not the cause of the general alteration 



