296 University of California Publications in Zoology. [VOL. 6 



rows (Ammodramus, Passerculus) . To quote a pertinent 

 description: "Among the many inconspicuous, plain, little 

 striped-backed sparrows of the Western United States, alaudinus 

 is one of the commonest, plainest, and most inconspicuous 

 Anywhere in the meadows, prairie grass or weed patches, one 

 may dart out from under your feet, zig-zag over the grass 

 tops for a little way, and drop into the grass, hopelessly 

 lost until he is again forced to take wing. At a distance you 

 see and hear the birds giving their plain little song from the 

 top of a tall weed or fence stake, but on nearer approach they 

 drop into the grass and are lost." This characteristic is here 

 emphasized because in all of the species mentioned as unmarked 

 birds we shall find this or similar traits having a like bearing 

 on our problem, while in all of them the typical flocking habit 

 is lacking. The latter may be replaced by what might be termed 

 a spurious form of flocking. As an instance : the rufous-crowned 

 sparrow (Aimophila ruficeps), common on the Berkeley hills, 

 may be surprised feeding in open patches when it at once takes 

 to brushy cover far from which it does not stray; and when 

 traveling moves in loose bunches of scattered individuals flitting 

 from bush to bush unostentatiously. 



Field ornithologists wall observe, however, that others of the 

 birds here mentioned are in some sense gregarious and gather at 

 certain seasons for migratory or other movements. We have, 

 however, evidence to the effect that such movements are some- 

 times, if not always, essentially different from typical flocking. 

 Two western sparrows from the arid region are frequently seen 

 in considerable numbers moving from their southerly winter 

 range to a summer habitat to the northward. To the casual 

 observer they might appear to be "flocking birds." A quotation 

 from a memorandum made by Mr. Grinnell during the recent 

 Museum Expedition to the region along the Colorado Biver, will 

 show the error of such conclusions. 



"Both Spizella breweri and 8. socialis are now abundant on 

 the desert in migrating flocks, not flocks, however, in the sense 

 that pipits flock, but scattering companies. Each individual in 

 a company moves wholly independently of any other; and they 

 do not move en masse when alarmed, but helter-skelter in different 



