74 University of California Publications in Zoology [Vol.12 



the willow association, yet not above the high-water mark. It is pres- 

 ent quite regularly as a tract along the outer margin of the willow 

 association, often only a few feet in width, but sometimes, as for 

 example near Pilot Knob, as much as two hundred yards in width. 



The arrowweed grows to a very uniform height, varying in different 

 places from three to over eight feet; and the slender straight stems 

 stand so close together as effectually to bar rapid progress through 

 the more luxuriant tracts. The plant is of perennial growth, but only 

 during the season of blossoming, April and May, does it appear to be 

 particularly favored by insects. In many places there is mixed willow 

 and arrowweed, in fewer places quail-brush and arrowweed, either 

 combination being evidently more attractive to birds than the arrow- 

 weed alone. 



The only resident bird finding its maximum abundance in the arrow- 

 weed association is the song sparrow (Melospiza id (India saltonis). 

 Even here the suspicion is aroused that this association is sought more 

 for cover because of the peculiar manner of growth of the constituent 

 plant, than as a food-producing area. For the song sparrow forages 

 freely into both adjacent associations. 



Of mammals, not one can be said to find its maximum abundance 

 in the arrowweed association. The few species regularly trapped there 

 were all more prominent constituents of adjacent associations. There 

 would be little reason for the recognition of the arrowweed association 

 as distinct from the willow association if it were not for its large extent 

 and the conspicuous absence from it of a great many of the elements 

 abundant in the latter. 



Quail-brush Association 



Lophortyx gambeli : max.; resident Pipilo aberti: min.; resident 



Zonotrichia leueophrys leucophrys: Oreospiza ehlorura: min.; transient 



min.; transient Guiraca eaerulea lazula: max.; sum- 



Zonotrichia leucophrys gambeli: mer 



max.; winter Oporornis tolmiei: max.; transient 



Melospiza melodia fallax: min.; win- Geothlypis trichas occidentalis: max.; 

 ter transient 



Melospiza melodia saltonis: min.; res- Toxostoma crissale: min.; resident 



ident Polioptila plumbea: min.; resident 



Pipilo maculatus curtatus: min.; win- 

 ter 



