^f- 



'I- 



ffl 



I- 



b: 



h 



not (lot nci It OH irof mi nor iio\ jqc/t fpo /9// 



FIG. I. CURVES OF (I) CHICKADEE, (II) PINE GROSBEAK. (Ill) PINE SISKIN, 



AND (IV) REDPOLL 



(14) 



