I^ 



'^^ 



a 



h 



B 



h 



ii»i not nfi ttOH iref mc tier /ro% /9o9 /f/0 /9/f 



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



AND (IV) REDPOLL 



(14) 



