SPIIYRAPIOUS THYROIDEDS. 551 



SPnYBAPICUS THYROIDEUS 

 Bi-own-licndod Woodpecker; Willintiisoii's Woodpecker. 



Picus thiiroidetis, Cassin, Pr. Ac. N;it. Sci. Pliilad., 1851, o4(). 



tSpkyra-picus thyroifieiis, Baird, Birds N. Am., 1S5.S, IOC; Cahil., 1859, No. 89 — 

 COOPEK, Oni. Cal., T, 1870, o94.— Couks, Key, 1872, 195; Clieck List, 187.3, 

 No. 304; Birds N.W., 1874, 288.— B. B. & B., Hist. N. Am. Birds, II, 1874, 

 547, pi. L VI, fig. G ("<?"=? witb red .streak on throat !).—Hbnshaw, Am. 

 Nat., 1874, 242 [Identity of thyi-ouleiis and ^' williamsoni" demonstrated]; 

 Wheeler's liep., 1875, 304. 



Picus unlliamsmn, Newbekky, Pacific U. \i. Rep., VI, 1857, 80, pi. xxxiv. fig. 1 

 (young 5 , or adult i with red ot throat destroyed by action of alcohol ; for- 

 merly siippo.scd to be 9!). 



Sphyrapicus unlliamaom, Baird, Birds N. Am., 1858, 105 ; Cat. N. Am. Birds, 1859, 

 No. 88.— Cooper, Orn. Cal., I, 1870, 393.— CouES, Key, 1872, 195; Check 

 List, 1873, No. 305.— B. B. & R., Hist. N. Am. Birds, II, 1874, 54.5, pi. li, 

 fig. 5. 



The discovery of the astonishing fact that the Brown-headed Wood- 

 pecker {S. thyroideus, Cass.) and WilHamson's Woodpecker {8. wiUiamsoni, 

 Newb.) are female and male of the same species, is due to the field-obser- 

 vations of Mr. H. W. Henshaw, the accomplished ornithologist of Lieutenant 

 Wheeler's expedition; the fact being first announced in 1874, in an arlicle 

 in the American Naturalist (Vol. VIII, p. 242). A suspicion that the two 

 might eventually prove to be difi'erent i)lumages of one .species several 

 times arose in our mind during the course of oiu- 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 tvilliamsoni the adult, proved 

 erroneous, however ; and it never occurred to us that the differences might 

 be sexual, an oversight caused chiefly by the circumstance of our having 

 seen in collections many specimens of thyroideus with a red streak on the 

 throat and marked as males, while the tj^pe specimen of tvilliamsoni had a 

 white streak on the thro'at and was said to be a female. We were thus 

 entirely misled by the erroneous identification of the sex in these speci- 



