7 2 A. Chadbourne on Individual Dichromatism. Q " t 



feathers taken from the breast on Dec. 21, were markedly tawny 

 toward the base. From Nov. 1 until Dec. 21, a total of fifty- nine 

 feathers had been lost by the two birds, but from this number, 

 forty-two must be deducted — (9 lost because of my effort to 

 mark them, 4 tail-feathers, 15 feathers evidently of the younger 

 plumage, and the remaining 14 lost in a fight between the Owls 

 for the possession of a mouse). This leaves for each of the Owls 

 a total loss of nine feathers during the change described above ; 

 yet on one of the birds, as we have seen, the majority of the 

 feathers were characteristic of the red-brown phase. 



On Dec. 22, the Owls were sent to some Owl-loving friends in 

 the country, where they could have space to fly about, and we 

 hoped to have some young Owlets later. At this time the liver 

 was stopped and they were fed upon raw meat. Every cast-off 

 feather was carefully preserved and labelled, and I heard often of 

 my pets, but especially about the color of the plumage. There 

 seemed to be rather a loss, than an increase of the red-brown 

 effect as time went on, and this was very evident, or at least I 

 thought so, on Jan. 17, when I saw the surviving Owl, which was 

 the larger red-brown female. The smaller and grayer bird had 

 been killed and partly eaten by the other on Jan. 3. 



On Jan. 19, the other Owl was found dead in her cage. She 

 was sent to me and is now in my collection, No. 4397. A careful 

 examination showed that the organs were all healthy macroscopi- 

 cally, but the bird was much emaciated, there being almost no fat 

 about the kidneys and mesentery, and but little in the orbits. 

 This was a marked contrast to the fatty degeneration from over- 

 feeding which I believe is usual in captive Hawks and Owls. 

 The condition of the bones of the skull proved that the bird was 

 less than a year old. 



This ends the history of my two pets, which I have intentionally 

 given at considerable length. It seems certain that in the larger 

 female Owl there was (1) a change from the typical gray to the 

 characteristic, though not extreme phase of red ; (2) and that this 

 was neither caused, nor accompanied by appreciable '•feather loss ' 

 (so-called ' ?nolt '); (3) nor can it have been wholly, if at all, depend- 

 ent upon ?iew feather growth ; and (4) it is also evident that there 

 was a distinct change in the color of the individual feathers, which 

 were apparently mature, as seen under the microscope. 



