LIFE HISTORIES OF NORTH AMERICAN DIVING BIRDS. 187 
no constant difference. There is much individual variation in the 
young of all four. I have had so much difficulty myself in identify- 
ing young murres, in the rookeries where both species breed, that I 
have learned to look with suspicion on all specimens in collections, 
which may not have been correctly identified. Mr. William Palmer 
(1899), however, says: 
The downy young of californica would seem to differ from arra in the dry 
skin by being of a paler color, and by having the upper edge of the white of the 
under parts blending into the dark neck color, instead of being bluntly and 
sharply separated, as in arra. The first feathering to appear on the young 
bird is on the wings and scapulars, along the sides of the breast and across the 
lower neck. Soon the down begins to drop off between the nostrils and the eyes 
and around the mouth and the base of the lower mandible, and as the birds get 
older the new feathering extends across the back, up the sides of the neck, and 
all over the under parts up to the bill. At the same time the feathering extends 
around the eyes and bill and running well back of the eyes, so that the only 
remains of the downy plumage is on the top of the head, extending down the 
back of the neck almost to the scapulars, scattering down the back, and ex- 
tensive about the rump, where it is still attached to the tips of the new feather- 
ing beneath. 
The sequence of plumages to maturity and the seasonal molts and 
plumages are of course similar to those of the common murre; in fact 
the greater part of what I have learned about the plumage changes 
of the species has come from a study of the large series of specimens 
which have been collected on the California coast. 
Behavior—In its feeding habits, flight, swimming and diving 
habits the California murre does not differ from its Atlantic rela- 
tive to any extent. Mr. Dawson (1909) says that its “notes consist 
chiefly of a mumbled and apologetic ow ow, or a louder arry of 
protest; but occasionally the birds explode in stentorous kerawks, 
absurdly out of character with their mild eyes.” 
On their breeding grounds the poor murres have many enemies, 
among which the large gulls are the most formidable, next to man. 
Any of the larger species of gulls which happen to be breeding 
near the murres love to feed on the eggs and young of the latter, 
but the western gulls on the Farrallone Islands are apparently the 
boldest and most successful robbers. Mr. Ray (1904) writes: 
From my own observations I do not think that in a battle royal the gull with 
its hooked bill has any advantage over the murre with its stiletto-like weapon, 
but succeeds in its high-handed robbery by better control of wing and foot and 
overwhelming numbers. The gulls swoop down when the murres have been 
flushed from their eggs and secure the booty, or a number by harassing a 
single bird simultaneously from all sides finally start the egg a rolling. It is 
amusing to see a bob-tailed, erect, soldier-like murre with an egg between its 
legs and a single swaggering gull endeavoring to secure it. Hvery time the 
gull cranes its neck forward for the egg the murre also bends with a vicious 
snap of its bill, which the gull is wise to dodge; and thus the birds will keep 
salaaming, like two polite Japanese, until another gull comes to aid its fellow 
