476 Birds of Colorado 
close to the surface with a rapid chattering note. Occa- 
sionally it alights on a rock or stone in mid-stream, and 
commences a series of little curtseyings or bobs, at the 
same time flicking its tail and alternately compressing 
its body and spreading its wings. It is this habit which 
has got it its name of Dipper. Presently it plunges 
into the icy water and dives with the help of its wings, 
or even walks along the pebbly bottom quite submerged, 
in search of the small water insects which it feeds on. 
In winter it will freely go below the ice, reappearing 
at some air-hole a few yards off, without hesitation. 
At this season it is often found at mountain lakes, 
especially if there is open water, owing to warm springs. 
It is a somewhat unsocial bird, and a single pair usually 
monopolize a stream or section of a stream to the 
exclusion of others. The song is clear and sweet, some- 
what Wren-like in tone ; according to Drew it is to be 
heard all the year round, both in winter and summer. 
The nest (Plate 16) is placed on a rocky ledge over- 
looking the stream, on an island rock, behind a water- 
fall, or sometimes under a bridge, but nearly always 
within reach of the spray of the water, so that it is always 
moist and damp. It differs somewhat in shape in order 
to suit the cavity where it is situated, but is nearly 
always oven-shaped, a little longer than broad, with a 
front entrance. It is constructed chiefly of mors, with 
some decayed leaves and other rubbish, strongly put 
together in a wet state. Inside is the nest proper, saucer- 
shaped, about 14 inches deep and 3} wide. It is 
composed of a peculiar non-absorbent wiry grass, lined 
with a few willow leaves flat and intact, and all perfectly 
dry. The nest harmonizes with its surroundings, and 
is made use of after repairs year after year, probably 
by the same pair of birds. The hen undertakes most 
