ELEVENTH ANNUAL REPORT. 179 
SAW-WHET OWL. SCREECH OWL. 
GROUP VI.—-SCREECH OWLS, Otus. 
The Screech Owl, Otus asio (Linn.), is the commonest owl 
about our houses, and the one which, in daylight, is most often 
the object of persecution by mobs of small birds. These seem 
instinctively to recognize their hereditary nocturnal enemy, and 
to appreciate its comparative helplessness in the blinding light of 
dav. 
Its name is undeserved, for the ordinary call of these birds, far 
from being a screech, is a tremulous, quavering series of notes, 
not at all unmusical, especially to those who associate it with 
pleasant memories. 
Screech Owls do not migrate, and even in winter do not wander 
far from their favorite hollow tree. There is hardly any orchard 
of old gnarled trees which does not shelter one of these fluffy owls 
deep within some hollow trunk. 
A curious phenomenon of color is found in a number of spe- 
cies of owls, but is especially marked in the Screech Owls. This 
is called dichromatism—two distinct color phases being found, 
which, so far as we know, are independent of age, sex or season. 
‘If we take four or five young birds from a nest and rear them by 
