LIFE HISTORIES OF NORGH AMERICAN DIVING BIRDS. 93 
The bill of the puffin is in truth a mask, for it is large and bril- 
liant only during the season of courtship, and is mostly cast off to be 
repla¢ed by a smaller, duller one for common use the rest of the 
year. The bill is the same in the two sexes, and, at the height of the 
breeding season, is a brilliant scarlet with triangular patches of steel 
blue at the bases of both mandibles; about the middle of the upper 
mandible, on either side, is a narrow band of white. The commissure, 
bare of feathers, is a brilliant orange. The whole inside of the 
mouth and tongue is a light yellow. Nor is this all, for the eyes 
during the courtship season are provided with a narrow horizontal 
horny line below, and one running diagonally back above while the 
edge of the eyelids is a vivid vermillion. The eyes themselves are 
smal] and blue-black, and sparkle in the wonderful setting. 
After the breeding season the puffin puts aside its mask by shed- 
ding the following pieces, according to Coues (1903) : 
1, Basal rim or collar; 2, nasal case or saddle; 3, mandibular case or shoe; 
4, 5, strips at base of mandible, one on each side; 6, 7, subnasal strips, one on 
each side; 8, 9, prenasal strips one on each side. 
The horny appendages of the eyelids are also shed. The horny 
molt by which the whole bill becomes smaller takes place at the same 
time with the feather molt in August and September. The orange 
skin at the commissure becomes pale and shrunken and the feet 
change from brilliant orange red to yellow. 
Food.—The food of the puffin is almost exclusively fish and on the 
Labrador coast the capelin seems to be their favorite. Crustacean 
and other forms of marine life are doubtless also eaten. 
Behavior.—Pufiins are as a rule unsuspicious and generally allow a 
close approach. As one approaches in a steamer or other boat, the 
swimming bird shows its anxiety by nervously dipping its head into 
the water from time to time. Then it is apt to show the greatest in- 
decision as to which action to adopt—flight below the water or above. 
Both actions—aerial as well as subaqueous—can be described as 
flight, for the wings, although held somewhat differently, are as vig- 
orously used below the water as in the air. In the former as in the 
latter case the feet are not used but trail behind. One can easily 
observe the beginning of the subaqueous flight, for the wings are 
flapped out for their first stroke as the bird enters the water. Unless 
the wind be strong against them, they have great difficulty in rising 
from the water, and often splash along the surface for some distance 
before they can rise above it. Many a time they give up the at- 
tempt and rest before trying again, but often continue the flight by 
dipping below the surface, without a pause in the process. I have 
often seen them emerge from a wave, fly across the trough and enter 
the next wave without apparent change in their method of propul- 
sion. Again I have seen them come out of the water flying, only to 
