104 BULLETIN 107, UNITED STATES NATIONAL MUSEUM. 
CERORHINCA MONOCERATA (Pallas). 
RHINOCEROS AUKLET. 
HABITS. 
This curious auklet, the largest of its group, is a bird of our more 
northern Pacific coast; it is not so well known, as its abundance at 
certain points should justify, because of its nocturnal habits on its 
breeding grounds; like the petrels it is seldom seen by daylight except 
when unearthed in its nesting burrow. It is essentially a bird of the 
open sea, seldom entering the straits and inside passages and never 
coming onto the land except to breed, coming and going during the 
hours of darkness. ‘ 
Nesting.—One of the principal breeding resorts of this species is 
Destruction Island, off the coast of Washington, which Mr. W. Leon 
Dawson (1908@) has described as— 
a flat-topped island with sharply sloping or nearly perpendicular sides, rising 
60 feet above tide. Covered by dense growth of vegetation, chiefly salmonberry 
and salal thickets growing to height of a man’s head, or higher on top; same 
with grass and bushes of other sorts on sides. Composed of deep loam (guano?7), 
clay, gravel (incipient conglomerate of Pleistocene age) in descending series, 
resting unconformably upon the upturned edges of Miocene sandstone. Exten- 
sive area of sandstone reefs exposed on all sides of island at low tide, includ- 
ing ribs and ridges of sculptured rock unreached by water save in time of 
Storm. 
He estimated that about 10,000 rhinoceros auklets were nesting on 
this island. 
Mr. Dawson (1909) has given us the following attractive account 
of the arrival of these auklets on the island: 
Late in April the auklets, stirred by a common impulse, muster from the 
wide seas and move upon Destruction by night. If there has been any scouting 
or premature development work, it has been carried on by night only and has 
escaped observation. In fact, it is a point of honor among the auklets never 
to appear in the vicinity of the great rookery—or aukery—by day. At the 
tribal home-coming, the keepers tell us, there is a great hubbub. If the location 
be a brushy hillside, the birds upon arrival crash into the bushes like meteors 
and take chances of a braining. Upon the ground, they first argue with old 
neighbors about boundaries. If growls and barks and parrot-like shrieks mean 
anything, there are some differences of opinion discovered. Perhaps also the 
details of matrimony have not all been arranged, and there is much screaming 
avowal. 
Gradually, however, order emerges from chaos, and the birds set to work 
with a will renovating the old home or driving new tunnels in the loam, 
sand, clay, or even hardpan. The burrows are usually 5 to 8 feet in length 
and about 5 inches in diameter, terminating in a dome-shaped chamber a 
foot or more across and 7 or 8 inches high. Each tunnel has a spur or blind 
alley which, presumably, is occupied by the male during the honeymoon. For 
lining, the nuptial chamber boasts nothing more pretentious than a few dead 
salal leaves and a handful of dried grasses. The amount of labor involved in 
this home-delving is very considerable. My guide once took an egg from a 
