WILLIAMSON'S SAPSUCKER 155 



they were for some time regarded as two distinct species. The fe- 

 male was the first to be described by John Cassin (1852, p. 349), based 

 on a specimen collected by John G. Bell in Eldorado County, Calif. 

 Under the name black-breasted woodpecker {Melanerpes thyroideus)^ 

 Cassin describes and figures (1854) the adult female as the male o£ 

 the species and says of the female : "Similar to the male, but with the 

 colors more obscure, and the black of the breast of less extent and 

 not so deep in shade," which is a very fair description of the imma- 

 ture female. The male was discovered and described and figured by 

 Dr. Newberry (1857, p. 89, pi. 34) under the name Picus wiUiam- 

 sonii, based on a specimen collected by him on August 23, 1855, on 

 the shores of KHamath Lake, Oreg. Baird, Cassin, and Lawrence 

 (1860) give a very good description of an adult male, as the male 

 of the species, but say "female with the chin white instead of red," 

 which, of course, is the immature male. Thus we have the adidt 

 of each sex regarded as the male of a species, and the young bird 

 of each sex regarded as the female of a species. With careless, or 

 improper, sexing of specimens, such an error might easily occur, 

 but it is remarkable that it remained so long undiscovered. Baird, 

 Cassin, and Lawrence (1860) describe the male as Sphyrapicus 

 wilUamsonii Baird, Williamson's woodpecker, and the female as 

 Sphyrapicua thyroideus Baird, brown-headed woodpecker. J. G. 

 Cooper (1870), in the Geological Survey of California, edited by 

 Baird, follows the same error but calls the female the round-headed 

 woodpecker. Even Baird, Brewer, and Kidgway, in their history of 

 North American Birds, had not discovered the error, for they use 

 substantially the same nomenclature. 



It remained for Henry W. Henshaw (1875) to discover the true re- 

 lationship of the two supposed species and clear up the previous mis- 

 understanding. He writes: "Wliile near Fort Garland, I obtained 

 abundant proof of the specific identity of the two birds in question; 

 loilliamsonii being the male of thyroideus. Though led to suspect 

 this, from finding the two birds in suspicious proximity, it was some 

 time before I could procure a pair actually mated. A nest was at 

 length discovered, excavated in the trunk of a live aspen, and both 

 the parent birds were secured as they flew from the hole, having just 

 entered with food for the newly hatched young." 



Mr. Ridgway (1877) comments on the discovery as follows: 



A suspicion that the two might eventually prove to be different plumages of 

 one species several times arose in our mind during the course of our field-work, 

 the chief occasion for which was the very suggestive circumstance that both were 

 invariably found in the same woods, and had identical manners and notes, while 

 they also agreed strictly in all the details of form and proportions, as well as 

 in the bright gamboge-yellow color of the belly. Our theory that thyroideus was 

 perhaps the young, and wilUamsonl the adult, proved erroneous, however; and 

 it never occurred to us that the differences might be sexual, an oversight caused 



