LIFE HISTORIES OF NORTH AMERICAN DIVING BIRDS. 169 
above. I also noticed a number of pairs nesting under the wooden platform 
that overhangs the rocks at North Landing. It is usually several days after 
laying the first egg before the bird lays the second. 
In the Puget Sound region the pigeon guillemot has frequently 
been found nesting in high cliffs or clay banks, sometimes 200 feet 
above the sea, where it excavates its own burrows. Dawson (1909) 
writes: 
In excavating a tunnel in a claybank the bird uses beak and claws and is 
forced at the outset to maintain herself in midair, a task which, by reason of 
her shortened wings, she accomplishes with no little exertion and infinitely 
less grace than that, say, displayed by a bank swallow. Not infrequently the 
bird encounters a bowlder afew inches in, and then the task is all to do over 
again. If, however, excavation has progressed sufficiently, the tunnel is 
continued at right angles. These tunnels are driven at any height which 
pleases the pigeon’s fancy, and most of them are accessible only by rope, 
although Mr. Bowles records an instance near Tacoma of a tunnel which was 
placed only 2 feet above the beach line. Incubation lasts a little over three 
weeks, and eggs are oftener hatched‘ after the 10th of July than before that 
date. The same burrows, if undisturbed, are used year after year.. 
Throughout the whole length of the Aleutian chain the pigeon 
guillemot was one of the common birds, sitting in little groups on 
the kelp-fringed rocks about the harbors or flying out around us in 
circles to satisfy its curiosity. We found it nesting during the 
latter half of June under the piles of loose rocks and bowlders along 
the shores, at the bases of rocky cliffs, as well as in the crevices in 
the rocks above. Farther north, on the rugged headlands of St. 
Matthew and Hall Islands, we saw a few pigeon guillemots flying 
out from the crevices in the lofty cliffs or sitting in little groups 
on the ledges among the puffins, auklets, and fulmars. They were 
undoubtedly nesting here in the inaccessible crevices in the rocks, 
where the nests of all these species were beyond our reach. 
Some observers state that the guillemot gathers small stones to 
line its nest, but this hardly seems likely; perhaps it may prefer to 
select hollows in which such small stones have accumulated, but 
it frequently lays its eggs on the bare rock or ground or in whatever 
débris it happens to find in a suitable cavity. It may scrape together 
into a pile what material is.available within easy reach, but I doubt 
if it actually brings in any new material. The pigeon guillemot 
regularly lays two eggs; generally several days intervene between 
the laying of the first and second eggs, during which time incubation 
is going on. 
Eggs—The eggs of the pigeon guillemot closely resemble those of 
the black guillemot, but they average slightly larger and are usually 
more heavily and more handsomely marked. The shape varies from 
pointed ovate to elongate ovate. The ground color varies from 
“pale glaucous green” to greenish white, bluish white, or pure 
