296 Distribution of Land Birds. [zoe 



7iutialliy Guiraca c^ridea eurhy^icha^ Progne siibis hesperts, Vireo 

 bellii piisillits, Harporhynchiis, redivivus and Poliopiila ca^ridea. 

 Such widely distributed forms as Speotyto ainicMlaria hypogcEa and 

 Corviis ani€rica7i7ts appear to have their centers of distribution in 

 this Area, but spread out both to the north and south in valley re- 



(Geococcyx calif orniamis) 

 indicates most strongly the Sonoran derivation of the fauna, while 

 such southern genera as Coccyzus, Pe7ic(^a, Guiraca ?i\\d Polioptila 

 point in the same direction. UnHke the two Areas of the Boreal 

 Province, we apparently do not in the Californian Area find that its 



characterizing features grow more pronounced as we go northward, 



gions 



but are distributed over the entire region with tolerable uniformity. 

 Before considering the Sonoran Area it may be well to take 

 up the Transition Region, which seems to be more intimately con- 

 nected with the preceding Area than with any other. I have 

 already mentioned a considerable number of forms which are char- 

 acteristic of the Californian Area which are also found equally com- 

 mon in this southern coast district; but in order to establish it as a 

 Transition Region, we must also find some species which breed 

 there which are characteristic of the Boreal Province and not of the 

 Sonoran. An excellent example of this is afforded by Harrises 

 woodpecker ( Dry abates villosus harrisii), the distribution of which, 

 as illustrating the boundaries of the Transition Region, may be con- 

 sidered in more detail. This bird is a resident of the Boreal Areas 

 of California and of the Transition Region, but does not breed in the 

 Sonoran Province. Quoting from Baird, Brewer and Ridgway's 

 N. A. Land Birds (11, p. 509) : ** In California Dr. Cooper found 

 this chiefly a northern bird, frequenting the forests of all kinds up 

 to the summits of the Sierra Nevada, and also resident as far south 

 as Santa Barbara, descending, in winter, to the eastern branches of 

 the Colorado and to Tejon Pass, He found it more common in the 

 higher Coast Range near Santa Cruz, and still more so towards the 

 Columbia River." Mr, Belding, in regard to its distribution in 

 Central California, says^: ^ Tolerably common summer resident of 

 the fir forests, apparently driven down from the higher Sierra in 

 winter, though I saw one at Donner Lake, November 16, iSS4,and 

 a few at Big Trees, January, 1870, when there was but little snmv ' 



•Land Birds of the Pacific District, p. 59. 



