Discoloration of Plumage in Certain Birds
Discoloration of Plumage in Certain Birds. It may be worth while to notice the fact that many birds taken near cities have the plumage greatly discolored. Whether this is due to smoke, ashes, coal dust, or charcoal of burnt stubs I am unable to say. From their appearance it might be any of these agencies. About Denver it may be due to the smelter smoke. As to a certain Otocoris, sent to Dr. Jonathan Dwight, Jr., he said: "and 1077 [arenicola] is of course soiled with coal dust or some such thing, perhaps from feeding on ash heaps." Near Denver the birds which show the greatest amount of dirt on their plumage are the house finches. Every feather is greatly darkened by the extraneous substance and the red areas are so toned down as to be inconspicuous. In regard to this species I believe Mr. Ridgway has suggested that the birds feed in burnt timber. In the vicinity of Denver, at least, it is rather doubtful if this be the case.
In the same locality Anthus, Lanius, Junco and Ammodramus have also been taken with soiled plumages. Coming now to California, we find a smoky plumage in Ammodramus, Thryomanes, Anthus and Zonotrichia, all taken in the vicinity of San Francisco. Mr. Slevin, to whom I spoke of the matter, said that Colaptes hung around the roofs of buildings in Alameda and probably got dirty from sliding on the shingles, a theory which seems quite probable. In his collection he showed me specimens of Colaptes, Accipiter and Regulus, from Alameda, and a Dryobates from Aiken, S. C., all very much soiled.