BIRD ROCK 177 
variability in marking which suggests that the 
white stripe of the Ringed Murre is a similar indi- 
vidual peculiarity. 
Next to the Murres the Kittiwakes are probably 
the most numerous birds on the Rock. Doubtless 
for the reason that they select the less accessible 
ledges where their eggs can not be so readily taken, 
their young were more advanced than those of any 
other of the birds breeding here. Their nests, rather 
bulky structures of seaweed, which often projected 
well over the edge of the ledge on which they were 
built, contained only young with their parents, one 
or two birds constituting a brood.” 
Kittiwakes were never observed perching on the 
upper ledges or rim of the Rock in the situations 
commonly selected by Murres, Razorbills, and Puf- 
fins. The last-named species, in fact, was never seen 
92. Entrance to Puffin’s burrow. 
resting far from the top of the Rock, and its nests 
were placed in burrows excavated on the summit of 
the Rock, at the west end. Occasionally advantage 
13 
