Voi. xiin 
1896 J LHADBOURNE 072 Individual Dichromatism. 3 2 j 
Ank, XIII, Oct., 1890 , pj>. 3 Z/~S\ 
EVIDENCE SUGGESTIVE OF THE OCCURRENCE OF 
‘ INDIVIDUAL DICHROMATISM ’ IN 
MEGASCOPS ASIO. 
BY ARTHUR P. CHADBOURNE, M. D . 1 
The common Screech Owl and some of its varieties are typical 
examples of dichromatism, which may be defined as the occurrence 
of two distinct phases of color in different individuals of the same 
species, entirely independent of age, sex, or season. It is evident 
that “ the occurrence of two distinct phases of color ” in the same 
individual , if “ independent of age, sex, or season,” must consti- 
tute an individual, , as distinct from the specific form of dichroma- 
tism. The following account of a pair of Screech Owls shows 
that ‘ individual dichromatism ’ probably occurs in this species, 
though it is doubtless infrequent, and possibly found only under 
artificial or even diseased conditions. 
Two Screech Owls ( Megascops asio), said to have been taken 
from the same brood late in the spring of 1894, were sent to me 
about Nov. 1, 1894. Both birds were in typical gray plumage, 
but a minute examination of the feathers was not made at the 
time, as the possibility of a change in phase had not been thought 
of, though, as an intermediate between the red and the gray 
plumage was wanted, it is safe to say that any reddish tint would 
have been noticed if present. The two Owls were in full 
autumn dress except for a few downy feathers near the so-called 
ears. 
1 he Owls were put in a large box cage, with the front of wire 
netting ; and a hole at one side opened into a second box, thus 
making a dark retiring place, that was never used. Six times 
each week they were given all the raw beef or sheep’s liver that 
they wanted ; but the seventh day they fasted. Fresh water for 
drinking and bathing, and also gravel were put in the cage daily ; 
while in addition dead guinea pigs, and occasionally live mice,' 
were to be had in the ‘animal room ’ at the Medical School, where 
1 Read at the meeting of the Nuttall Ornithological Club, March 4, 1895. 
41 
