May, 1921 THE PROBABLE STATUS OF THE PACIFIC COAST SKUAS 79 
in fact, they are the largest of all the species of Catharacta. Moreover, these 
birds, which were perhaps all adults, were much more mottled, or streaked, 
with lighter colors than the Monterey birds. 
There still remained one species, Catharacta maccormicki Saunders, with 
which I had made no comparisons, and I noticed in reading Dr. E. A. Wilson's 
(National Antarctic Expedition, vol. 2, p. 75) account of this species, that his 
measurements agree very closely with those of the birds from Monterey. [e also 
says that the young birds of C. maccormicki are dark colored and that “‘even 
the oldest adults are dark when freshly molted.’’ As I could not locate any spe- 
cimens of maccormicki in this country, I wrote to Dr. Hartert and he very kindly 
sent me, from the British Museum, their only specimen of this species in imma- 
ture plumage, a very young but fully grown and fully fledged bird, with some 
of the natal down still clinging to the tips of the feathers. But this also proved 
to be entirely different from the Monterey birds in color; it was a uniform ‘‘nen- 
tral gray’’ or ‘‘light mouse gray’’ (Ridgway), both above and below; the top 
of the head and back were no darker than the under parts; the wings and tail 
were darker, but not so dark as the birds in question. 
This left me still more in the dark than ever, as I had compared the puzz- 
ling birds with every known species of Catharacta. Jt was not until I went to 
New York and studied the extensive series of skuas in the American Museum of 
Natural History, mainly in the Brewster-Sanford collection, that I began to get 
any light on the subject. In their magnificent series of thirty-eight specimens 
of Chilean Skua (Catharacta chilensis) I was surprised to find four which 
matched the Monterey birds almost exactly. In talking the matter over with 
Dr. Robert Cushman Murphy, who is familiar with both Catharacta chilensis 
and C. antarctica in life, he told me that he had noted these dark-colored birds 
and had at first thought of describing them as a distinct species, but that he had 
since come to the conclusion that they were the young of chilensis. In support 
of this theory he said that these dark-colored birds were quite common on the 
coasts of Chile and Peru and that they associated freely with the ordinary rufous 
birds of this species. Also, he had actually proven by studies in the field that 
the young of antarctica, the resident form of South Georgia, are uniformly dar‘- 
colored, having watched a young bird develop from the downy stage. I have 
already shown above that this is also true of lonnbergi and maccormicki. 
Up to this time I had ruled out chilensis on account of its color, which is 
decidedly rufous in all specimens I had seen, though agreeing in size with the 
Monterey birds. But after examining this series and after talking with Dr. Mur- 
phy, I was forced to the conclusion that the birds in question are probably refer- 
able to Catharacta chilensis (Bonaparte). I am not, however, quite prepared to 
accept Dr. Murphy’s theory that they are immature birds and am more inclined 
to think that they represent a dark phase of that species. 
In the Catalogue of Birds in the British Museum (vol. 25, p. 315), under 
Megalestris chilensis, I read that ‘‘in less mature birds the chestnut color is 
neither so pronounced nor so extensive, but is always a strong characteristic of 
the species.’’ Furthermore, both of the Monterey birds are in fresh plumage 
and have recently molted; one of them (Mus. Vert. Zool., no. 17758) had not 
quite completed its molt when it was collected on August 4, 1916, for the outer 
primary in each wing is old and worn. As the first molt of the primaries in 
birds of this group usually occurs when the bird is from 14 to 16 months old, it 
may safely be inferred that these birds are more than one year old, at least. and 
