LARGE-BILLED SAVANNAH SPARROW 723 



pervading the gray of the enth'e upper parts and the streakmg of the 

 under parts." From the "normal" coloration, there are endless 

 variations which reach a pale gray at one extreme and a pale rufescent 

 or brick red at the other. He further states that "Sexual dichroma- 

 tism as well as individual variation is more m evidence in rostratus 

 than in any other Savannah Sparrow * * *." 



Food. — C. Cottam and P. Knappen (1939) examined 28 stomachs 

 of rostratus (14 in December, 3 in January, and 11 in March), 26 of 

 which were taken at Alamitos Bay, Calif., or San Luis Island, Gulf of 

 California, The other specimens were taken at Pasadena and El 

 Monte, Calif. Food was 39.21 percent animal, 60.79 percent vege- 

 table. A full stomach contained about three-quarters of a cubic 

 centhueter. Of the animal foods, crustaceans represented 22.67 

 percent of the total intake; of these, various species of crabs formed 

 10.71 percent. A variety of insects were next in order of importance, 

 supplying 8.36 percent of the food. Beetles (Coleo-ptera) composed 

 4.68 percent and unidentified insects, ants, and a lepidopterous cocoon 

 (Tineidae) made up the remaining 3.68 percent. On the average, 

 spiders composed only 0.39 percent of the total food, but one bird had 

 1 1 percent of its last meal composed of spiders. 



That small gastropods are readily acceptable is shown from the fact 

 that 10 of the 11 birds collected in March at San Luis Island had 

 ingested a relatively thin-shelled snail (Alarinula rhoadsi) in amoimts 

 varying from a trace to 55 percent of their meals. Snails supphed 

 18.45 percent of these 11 bu"ds, but averaged only 7.25 percent for the 

 entire 28 bu'ds. Miscellaneous gastropods contributed another 0.54 

 percent, making the total consumption of these mollusks 7.79 percent. 



Of the plant material 30.87 percent could not be identified otlier 

 than as seed fragments, woody debris, or rubbish. Grain supplied 

 22.96 percent, with wild oats (Avena jatua) present in the greatest 

 quantity (12.25 percent) and oats {Avena sativa), storksbill (Erodium 

 sp.) and Solanum sp. each contributing less than 4 percent of the total. 



A considerable difference was noted in the food of birds collected 

 in March at San Luis Island from those taken in December at Alamitos 

 Bay. The former group had subsisted on animal food, mostly 

 crustaceans and gastropods, to the extent of 53.73 percent, while the 

 Californian birds had taken insects, crustaceans, and gastropods 

 only to the extent of 22.29 percent. This would indicate that the 

 species is adaptable, feeding within limits on whatever is most readily 

 available. 



Voice. — W. L. Dawson (1923) describes a midwinter song of 

 rostratus (probably not at its fullest volume) as squeaky, and ending 

 in a pookish trill: Tsui tsut tsu wzzz tsut tsu wizzy weee. Having 



