1 914 ] Grinnell: Mammals and Birds of the Colorado Valley 



73 



throughout the year, chiefly by seepage. These were always located 

 back from the river near the outer edges of the broader valleys, where 

 they were least affected during flood time. They were marked by 

 growths of tules, sedge, and salt-grass, sometimes the latter alone, and 

 were usually surrounded by the arrowweed or willow association (see 

 fig. B). The little open water sometimes attracted a few transient 

 ducks and mudhens, but so far as known no water birds outside of 

 the Ardeidae remain to breed anywhere along the Colorado River. 



As may be noted from the list, but few animals were found to 

 frequent the tule association regularly enough to be considered dis- 

 tinctive features of that association. Of these, Reithrodontomys was 

 the onlv mammal finding its center of abundance there. 



Arrowweed Association 



Lophortyx gambeli: mill.; resident 

 (only as a forager) 



Geoeoccyx californianus: min.; resi- 

 dent (only as a forager) 



Astragalinus psaltria hesperophilus : 

 min.; resident 



Zonotriehia leucophrys leucophrys: 

 min.; winter 



Zonotriehia leucophrys gambeli: 

 min.; winter 



Melospiza melodia fallax: max.; win- 

 ter 



Melospiza melodia saltonis: max.; 



resident 

 Melospiza lineolni lincolni: max.; 



winter 

 Pipilo maculatus curtatus: max.; 



winter 

 Oreospiza chlorura: min.; transient 

 Vireo belli arizonae: min.; summer 

 Vermivora celata celata: min.; win- 

 ter 

 Dendroica townsendi: min.; transient 

 Oporornis tolmiei: min.; transient 



Peromyseus manieulatus sonoriensis: 



min. 

 Neotoma albigula venusta: min. 

 Perognathus penicillatus penicillatus: 



min. 



Sylvilagus auduboni arizonae: min. 



Mephitis estor: min. 



Spilogale arizonae arizonae: min. (?) 



Remarks upon tin: Arrowweed Association. — In its purity this asso- 

 ciation possesses only one conspicuous plant, the arrowweed (Pluchea 

 sericea), which, over extensive areas, grows so densely as to occupy 

 the ground to the exclusion of everything else (pi. 5, fig. 5). This 

 belt of arrowweed usually occupies slightly higher ground than dors 



