380 ORNITHOLOGY. 



of the Western Uejjion at this season, though in summer tlieir habitat may 

 be confined strictly to the area of Pacific-coast ih'ainage. This circum- 

 stance we have previously alluded to, in these words: — ^ 



"Another very remarkable peculiarity of the Wahsatcb region, which I wish par- 

 ticularly to mention in this connection, is the fact that in the case of representative 

 species or races, the Eastern or IJoi^ky ^loiiiitaiii forms breed there, while the more 

 Western forms replace tlietn in winter. Tims, Zonotrichia leiicophri/s and Juiwo hyemalis, 

 var. caniceps, are the only species of these two genera which breed on the Wahsatcb, 

 and they nest there very nnmeroiisly; but in the fall their place is taken by the western 

 Z. lcuco2)h)ys, vi\r. (jamhcli [ = intermedia] and J. Injemidis, var. oref/onus, which are un- 

 known in summer. Lanivireo solitaria, var. pUtmbea, breeds there, while var. solitariu, 

 coming from the northwestward, replaces it in autumn. The same is the case with 

 Tunlus pulluxi, xiir. auduboiii (suinmi'r resident), and var. nanus (autumnal migrant); 

 and apparently the case also with Helminthophaga riVjrjn/rt! (summer), and H. ruficapiUa 

 (autumn)."^ 



The eastern species occurring within the Basin were found to have 

 reached their maximum in the Salt Lake Valley and adjacent country to the 

 eastward, but, as was the case Avitli the western series, some of them had 

 intruded so far within the western domain as to reach the opposite side. 

 Thus, Tyramiiis carolinensis was not rare during the breecUnt/season in the 

 lower Tnickee Valley, almost at the foot of the Sierra Nevada. Ectopistes 

 migratoria was obtained in the West Humboldt Mountains, although the 

 only individual seen was a young one, and evidently a straggler. In the 

 East Humboldt Mountains, Turdus stcamsoni, Helminthophaga ruficapiUa, and 



iProc. Essex Inst., Vol. V, Nov., 1873, pp. 170, 171. [" Notes on the Bird Fauna 

 of the Salt Lake Valley and the adjacent portions of the Wahsatcb Mountains."] 



^ Other examples of species which have an extreme western or northwestern 

 distribution during the breeding-season, but which migrate in fall both eastward and 

 southward, are, Helminthophaga lutescens, Dendrceca occidentalis, D. toivn.sendi, and ISelas- 

 phonis rn/n.s, found as far east as the Clover Mountains, with the addition of Lanivireo 

 casaini, iVtVo.yx'cn guttata, PipHo orcgonus, Zonotrichia coronata, and Agrlaus guljcrnator, 

 which in September and October were obtained in the West Ilumboldt range. The 

 most plausible explanation of this eastward migration would appear to be found in 

 the supposition that nearly, if not all, these migrants were from the Valley of the 

 Columbia Kiver, whose main tributary, the Snake lliver, heads almost diiectly north 

 of the Great Salt Lake; the birds of the Columbia basin would naturally follow the 

 valleys of these upper tributaries as the route oiiering the least obstacle to their south- 

 ward passage, many species which do not breed eastward of the lower Columbia thus 

 regularly reaching the eastern border, if not the whole extent, of the Great Basin. 

 Whether their return northward is by the same route, remains to bo determined. 



