LIFE HISTORIES OF NORTH AMERICAN DIVING BIRDS. 105 
tunnel driven 10 feet straight into a clay bank; and I followed another through 
sand to a depth of 15 feet, only to find it empty. This last, I take it, was the 
work of a jilted suitor, venting his feelings by showing the coquette what a 
fine house she might have had. 
Prof. Lynds Jones (1908) also says of their burrows: 
The birds burrow into the perpendicular banks which face the ocean in many 
places, or into the turf-covered banks which are only a little less steep. The 
burrows may lead almost straight into the bank for a dozen to 15 feet, or more 
nearly parallel the surface, apparently depending somewhat upon the char- 
acter of the soil. The few attempts to burrow into coarse gravelly material 
were soon abandoned in favor of the sandy soil. A very few nest burrows 
were made within a foot of the surface of the turf and could be uncovered 
from above. Every burrow examined was forked, the shorter and unused 
branch invariably being the one nearer the face of the bank, while the used 
branch continued some distance into the bank, ending in a nest of grassy 
material mixed with feathers where the hole was enlarged for more room. 
Prof. Harold Heath (1915) found the rhinoceros auklet breeding 
still more abundantly on Forrester Island, southern Alaska, during 
the summer of 1913. He writes: 
Generally speaking, the rhinoceros auklet occupies burrows in the sloping 
sides of the island from the shore line to a height of from 400 to 500 feet, their 
number and distribution depending upon the nature of the soil and the char- 
acter of the surrounding vegetation. The most favorable nesting sites appear 
to be the dense spruce woods where the shadows are of such depth that ferns 
and underbrush find but scanty foothold, and the soil is soft and friable. In 
such localities over 400 burrows have been counted in an area 600 feet square, 
but where the salmon and elder berry are abundant, and ferns form a tangled 
mat, or rock outcrops are plentiful and the soil thin the nests are of less 
frequent oc¢urrence or are absent altogether. While no complete and accurate 
count is possible it is safe to say that not less than 15,000 pairs of these birds 
found a home on Forrester Island during the past season. 
Judging from this year’s observations, the breeding season commences in the 
latter half of May. At this time the old burrows, which have caved in during 
the winter or have become clogged with débris brought in by mice, are given 
a thoroughgoing cleaning, and the accumulation of spruce needles and cones, 
decayed grass, moss, leaves, stems, and earth scraped to the front of the 
entrance forms a conspicuous mound in many instances. In some cases the 
tunnels have already been cleared to some extent by the Cassin auklet and to 
a less degree by the ancient murrelet, but the relations of these birds appear 
to be undisturbed even when two species occupy the same home. 
As a general thing the opening of the nest is about the base of stumps or 
trees or under logs, and only rarely does it occupy open ground away from the 
forest. As to the burrow, it is a highly variable structure, neglecting the fact 
that it is at least 8 feet in length. In extreme instances it attains a length 
of fully 20 feet, and, as indicated in the accompanying diagrams, its con- 
figuration is subject to many variations. There is usually one main channel, 
rarely with two outlets, and from this there are one or more blind offshoots. 
In one of these the nest is frequently placed, but it is by no means a usual 
occurrence to find it close to the entrance as some of the Haidah men declare 
to be the case. 
