1913] Grinnell-Swarth: Birds and Mammals of San Jacinto 293 



adhering closely to the cover of these plants, it foraged also 

 through scrub oak, manzanita, and ceanothus, occasionally into 

 four-leafed pifion (Pin us parry ana) or sagebrush (Artemisia 

 tridentata). The forage depth of this vireo is between one and 

 five feet above the ground, rarely any higher. A person may 

 follow a bird around for twenty minutes, keeping track of it by 

 the oft-repeated song, without catching a view of it above the 

 level of the chaparral tops. 



We estimated that there was a pair of gray vireos for every 

 forty acres of suitable ground, thus giving an unusually large 

 forage area for the individuals of this species. The impression 

 was sometimes given that the population was much more dense, 

 but we decided that the far-carrying song tended to mislead in 

 this regard. Taking the above estimate as conservative, there 

 would be 16 pairs to the square mile. We are of the opinion 

 that there are about thirty square miles of the appropriate asso- 

 ciation in the San Jacinto region; so that the total number of 

 individuals of this rare bird in the region under treatment was, 

 in 1908, before the advent of the new broods, close to 960. 



As already to be inferred, the presence of the gray vireo is 

 most easily ascertainable through the peculiar and far-reaching 

 song. The birds themselves are very difficult to locate, except 

 by means of this song. The truth of this statement will be per- 

 ceived when it is further stated that after the close of the regular 

 song season, when much of the same ground was repeatedly 

 gone over by members of our parties, between August 5 and 27, 

 but one bird was seen. Only once was the song heard during 

 August, on the 16th, on the trail up Thomas Mountain from 

 Hemet Lake. During the last of May, and June, the song was 

 omnipresent in appropriate localities, from 5 :15 a.m. in one 

 case (May 21), to sundown. There seemed to be no cessation 

 during midday. 



The song of the gray vireo is loud and full-toned, in volume 

 and quality. In these respects it reminds the hearer strongly of 

 the Cassin vireo, yet with the twang and less deliberate utterance 

 of a western tanager. In measure, and in the suggestion of 

 alternate rising and falling inflection, it recalls the least vireo. 

 No note at all was heard, besides this song, which was apparently 



