SPIIYRAPICUS TDYROIDEUS. 55] 



Sl'HYRAl>ICDS THYJtOIDKUS 

 Bro\vii-tio:ulv(l \Voo<l|M><-k<-r; Williiimsoii's \Voo(l|tock«'r. 



Picux thijroideits, Cassin, Pr. Ac. Nat. Sci. IMiilad., 1851, M'X 

 Sphi/rcrpicm tlii/roideus, lUlKD, P.inls N. Am., l.s.-.S, l()(i; (Jatal., 1850, No. 89 — 

 Cooi'iCK, Orn. Ciil., I, 1S7(), .V.Il.-L'ouES, K.-y, m'J, 195; c'lii-ck Li.st* 187:3, 

 No. ;;04; iJiiiLs N.\V., 1S74. L'SS.—B. 15. & ]{., Ui.st. N. Am. Birds, II, 1874 

 547, i>l. Lvr, fig. G ("^"=? with letl strwik on throat!).— Uexsiiaw, Am! 

 Nat, 1874, 242 [Iilciitity ol thyroidem and '■ iclUiamsoni" demonstrated I- 

 Wheeler's liep., 187.",, ;394. 



Plcus williamsoni, Newberry, Pacilic R. 11. Eei)., VI, 1857, 89, pi. xxxiv. lig. 1 

 {young c5 , or adult i wlMi icd oi throat destroyed by action of alcohol' ; /or- 

 meiiy supposed to be ?!). 



Sj>hyra2>icits irilliamsoni, Bairu, Birds N. Am., 1858, 105 ; Cat. N. Am. Birds, 1,S59, 

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

 List, 187;j, No. 305.— B. B. & R., Hist. N. Am. Birds, 11, 1874, 545, pi. i.i, 

 fig. 5. 



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

 pecker {S. thyroidcus, Cass.) and Williamson's Woodpecker {S. williamsoiu, 

 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 article 

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

 might eventually prove to bo dill'erent plmiiagcs of one species several 

 times arose in our mind during the course of our field-work, the chief 

 occasion for which _ was the very suggestiTe 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 ibrm and proportions, 

 as well as in the bright gamboge-yellow color of the belly. Our theorv 

 that thyroideus was perhaps the young, and tvilliautsoni the adidf, pro\ed 

 erroneous, however ; and it never occun-ed to us that the differences mi"-ht 

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

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

 throat and marked as males, while the type specimen of uiUiamsoni had a 

 white streak on the throat and was said to Ijc a female. We were thus 

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



