LIFE HISTORIES OF NORTH AMERICAN DIVING BIRDS. 175 
N esting—The Bird Rock colonies have been so often described that 
any lengthy account of them would be unnecessary repetition. At 
the time of our visit, June 23 to 25, 1904, the total population of the 
rock was estimated as about 10,000 birds. We thought that the com- 
mon murres ranked about fifth in numerical strength, although not 
far behind the Briimnich’s murres in this respect. I estimated that 
the common murres numbered about 1,400. The murres and. Brin- 
nich’s murres were nesting in mixed colonies, arranged in long rows 
along the narrower ledges, such as were not available for gannets. 
‘The eggs were generally inaccessible, except with the aid of a rope, 
and were mostly on the lower or middle sections of the cliffs, but 
there were some which we could reach by going down the ladders 
and climbing around on the broader Jedges. Here the eggs were 
laid on the bare rock or on the loose soil accumulated by disintegrat- 
ing rock; they were laid in rows, about as close as the birds could 
sit, and usually with the smaller end pointing cutward. Nearly 
every one who has written about the eggs of the murres has called 
attention to their pyriform shape, which is supposed to cause them 
to roll in a circle, when disturbed, instead of rolling off the ledges; 
‘but anyone who has had much experience in murre rookeries knows 
that any sudden disturbance, which frightens the birds off their 
nests, generally results in a shower of eggs, showing that this theory 
aloes not always work out in practice. 
On-the flat rocky islands off the south coast of Labrador the murres 
evidently nested in compact open colonies, as is often the case with 
the California murres.. Such colonies were much more easily robbed 
of their eggs than the cliff colonies, which would account for their 
rapid extermination. Dr. Townsend writes me, in regard to one of 
the islands he visited near Cape Whittle: 
On one of these, Outer Island, off Coacoacho Bay, besides the nests of some 
‘600 pairs of double-crested cormorants, were about a thousand eggs of murres. 
The combined colony of these two species was crowded together on about an 
acre of the summit of the small rocky island. The large nests of the double- 
crested cormorant occupied every available site, and the eggs of the murres 
were thickly scattered between the nests. This was on July 14, and nearly 
all of the cormorant eggs had hatched and the young in various stages were 
clamoring for food. None of the murres’ eggs had hatched, some were fresh, 
Dut the majority were considerably incubated. As we landed on the island 
most of the adult cormorants took to flight but the murres allowed a close 
approach, and, as we walked among them, they shuffled out of the way, walking 
almost erect and moving their small wings like arms. Every now and then 
they would fall over on their bellies, and they often launched themselves head- 
long over the rocks in their efforts to take to wing. Everything was daubed 
with excrement, the nests, rocks, and eggs. Most of the murres’ eggs were so 
covered with the filth that their beautiful markings could not be seen, and the 
birds themselves had sadly soiled their white breasts. I counted a hundred 
eggs in the space 10 feet square. 
