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200 THE CONDOR Vol. XXIV 
than one would probably assume off-hand. The factors influencing his choice of 
notes are as follows: 
(1) Persistency of the sounds in the imitator’s environment. Such persistency 
determined by: 
(a) Seasonal status of “subjects” of imitation. All transients and irregulars 
would be eliminated since their notes would not persist in the imitator’s environ- 
ment for a sufficient number of weeks nor would they persist during the imita- 
tor’s impressionable period. 
(b) Associational preferences of subjects. Those of extremely lecal or re- 
stricted range would be eliminated. This counts out the Bell Sparrow (which I 
found only on the sagey west slope of Chalk Peak); the Western Bluebird, the 
Pine Siskin and the Linnet (which showed a decided preference for the west slopes 
down toward the Redwoods); and the Violet-green Swallow and Martin (whose 
aerial habits kept them a good part of the time out of hearing of our imitator). 
(c) Numerical distribution of subjects. Those of rare or occasional occurrence 
would be eliminated, namely, the Slender-billed Nuthatch, the Cabanis Wood- 
pecker, the Nuttall Woodpecker, Western Kingbird, the California Thrasher, the 
Cassin Vireo, the Lawrence Goldfinch, the Black-throated Gray Warbler, the 
Western Gnatcatcher, the Point Pinos Junco, Mountain Quail, the Tawny Creeper, 
Mourning Dove, Audubon Warbler. 
(d) Time of activity of the subjects during the twenty-four hours. Birds of 
nocturnal or crepuscular habits would be eliminated, ne the Poor-will and 
any owls that might inhabit the region. 
(e) General vocal strength of subjects. The following weak-voiced birds are 
eliminated: Creeper, Pygmy Nuthatch, Bush-tit, Bluebird, Siskin, Anna Hum- 
mingbird, Allen Hummingbird, Western Gnatcatcher. 
(f) General vociferousness of subjects. The Buzzard is eliminated as being 
silent. 
(g) Uniformity of utterance on the part of the subject. The Plain Titmouse is 
too versatile; does not stick long to any one note. The Thrasher, Black-headed 
Grosbeak and Purple Finch (whose persistent utterances are their songs) sing 
in a manner too long, ‘“‘diffuse’” and variable to allow any one sound to outstand. 
(2) Physiological conditions connected with the peculiar nature of the Ssyrinx and 
other vocal apparatus of the imitator. Obviously certain types of sound could not 
be managed by the comparatively unelastic and unpracticed syringeal membrane 
of the Brown Towhee. Thus at least two classes of sound would be physiologically 
unmanageable: 
(a) Too voluminous sounds, such as those of the California Quail, Band-tailed 
Pigeon, and California and Crested Jays (heavy chup-chup-chup notes of each, 
and the common zghrae of the former). 
(b) Too low sounds, such as those of the Mourning Dove and Band-tailed Pigeon. 
Applying the above tests to all of the birds recorded by me during my stay 
in the Santa Lucia Mountains, I find that I have eliminated all but nine. These 
nine represent birds which have one or two utterances to be heard persistently 
all day long every day during the summer months. Following is a list of the 
birds and their notes: 
California Woodpecker ‘‘varcob’’ and ‘‘cracker’’ 
Red-shafted Flicker ‘*klee-yuh”’ 
Ash-throated Flycatcher ‘‘kippy’’ and ‘‘kip-preer’’ 
Olive-sided Flycatcher ‘““neevue”’? and ‘“‘puip-puip-puip”’ 
Western Wood Pewee | ‘““heeeezzzz”’ 
Spurred Towhee ‘‘thwaaaa’’ and song 
Western Tanager song 
Western House Wren song 
Wren-tit 
common ‘‘tattoo’’ eall 
