The Western Gulls 
The case of the Pacific Coast Gulls offers a peremptory challenge 
in genodynamics. The dynamic evaluation of species, the appraisal 
of generic stock, of intergradation, and of isolated colonies,— these are 
fascinating problems in themselves; and in no other case do solutions 
appear so easy, so clear cut, or so important, as in the case of a species 
occupying detached island groups distributed over 24 degrees of longitude. 
I have already called attention to the fact 1 that the Western Gull at 
the extreme limit of its breeding range, viz., off the coast of Washington, 
appears to hybridize with L. glaucescens. A clear cut example of this 
came to light the year after “The Birds of Washington’’ was published, 
in 1910. When I had occasion to visit Grenville Point on the 27th day of 
August, a whining sound, coming from the crest of the Grenville Pillar, 
a detached rock some 100 yards distant, drew my attention to a very 
dark bird, a young gull, who was beseeching its wary parents for food. 
The old birds stood stolidly unheedful, but very alert to the danger 
ashore. Finally one bird made a scolding tour over my way. His 
(or her) wing-tips were absolutely devoid of black, a Glaucous-wing if 
there is any such thing. This bird’s mate, known to be such because 
these two were the only gulls on the rock, and because the chick addressed 
them both in turn and that repeatedly, was an unmistakable Western, 
having a somewhat darker mantle and wing-tips definitely black. 
And other such examples, less marked but cumulative in their total 
impression, met my gaze during an inspection tour of the Olympiades 
bird reserves, conducted in the early summer of 1910. It is very note¬ 
worthy, therefore, in this connection that eggs found in this debatable 
country, off the Washington coast, exhibit the highest degree of variation 
—due to the interplay of diverse stocks. Southern colonies, on the other 
hand, so far as examined, exhibit a notable uniformity in respect to the 
eggs. Save for a few “freaks,” due to deficiency in pigmentation, I 
did not find among a thousand nests examined, on the Southeast Farallon 
Island, one-fourth the range of variation that obtains on a single rock 
off the Washington coast (Split Rock), which boasts a population of only 
forty pairs. Evidently the Farallon colony is closely inbred, or at least 
reduced to uniformity through long isolation and the absence of any 
infusion of new stock. There is meat here, and a close study of cology 
will bring important conclusions to light. 
144 Birds of Washington,” 1909, Vol. IT., p. 726. 
