May 1 901.] i.AXD BIRDS or saxta cru/. corxTv. 3 



FAUNAL POSITION OF SANTA CRUZ COUNTY. 



The greater part of Santa Cruz County lies within the Pacific Coast 

 Transition Faunal Area.' This is a humid division of the Transition zone, 

 as defined l)y Dr. C. Hart Merriani. The belt extends from the vSanta 

 Barbara Mountains north as a narrow strip next to the coast to the vicin- 

 ity of Cape Mendocino, where it merges into the boreal Northwest Coast 

 District. Tliis Humid Transition- belt continues north nito the western 

 parts of Oregon and Washingtcni between the coast mountains and the 

 Cascade Range. In California the Humid Transition merges into the Arid 

 Transition on the east and occasionall5' into the Upj^er Sonoran. 



The Pacific Coast Transition Faunal Area is a region of heavy rain- 

 fall and of frequent fogs. In California the latter are especially prevalent 

 during the summer when there is little rain. As a result vegetation is 

 luxuriant beyond any measure to be found elsewhere in California, ex- 

 cepting, of course, the northwest coast. 



With this humidity is correlated a peculiarly equable climate. Through- 

 out the sunnner the mean temperature is low for the latitude, so that boreal 

 species^ of animals and plants are enabled to push sovithward in low alti- 

 tudes. On the other hand the season of reproduction is much prolonged 

 on account of this singularly uniform climate. This brings the sum total 

 of sunnner heat rather high for the region, and many Austral or Warm 

 Temperate types are thus enabled to flourish.'' 



In the Santa Cruz mountains all these conditions exist. The region 

 is characterized by a rather heavy rainfall, particularly that area known 

 as the Big Basin. The climate is temperate, yet frosts occur in the moun- 

 tain canyons as late as the last of May. But on the other hand the total 

 amount of summer heat is high and thus it is that many forms found in 

 the Sonoran valley to the east and south are likewise familiar residents of 

 the Santa Cruz Mountains.! 



.The Humid Transition portion of the Santa Cruz Mountains merges 

 into the Upper Sonoran on the outlying hills and valleys to the east and 

 southeast. This border land is usually one of great confusion in zone 

 l)oundaries, for plants characteristic of either zone will frecpiently be 

 found growing together in perfect amity. As a rule on these outlying 

 ridges, the up])er and hotter slopes contain a totality of forms character- 

 istic of the Upper vSonoran zone, while the Transition is confined to the 

 deep canyons. Many mountains are covered with extensive areas of 

 chamiso [ Adcnostonia fascicnlatu))i) which seem often to follow certain rock 

 formations.^ Thus it is we lind the ITpper Sonoran zone ranging up high 

 on these peaks, for the chamiso, which is characteristic of this zone is able 

 to crowd out everything but cha]>arral plants and shrubs, and a large 

 quantity of heat is let in. The region affords an excellent opportunity to 



1 See I,ife Zones and Crop Zones of the United States by C. Hart Merriam. Bui. lo, U. S. Dep't Agri. Div. 



Biol. Surv. 1898, p .27. 



2 This name will be used as a more convenient term for the Pacific Coast Transition Faunal Area. 



3 Among the birds may be noted Anorihuta hiemaUs pacifica, Cyatiocilta slelleri cardonacea. 



4 Such birds as Aphe/ocoina californica, Pipilo fusctis crissalis, Caipodaciis piiipi<reiis caii/oiniciis, I'ireo 



gilTiis s7c'aifiso>ii are examples. 



5 For instance those containing much lime seem to be preferred. 



