54 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I43 



It is conceivable, therefore, that the vocal repertory of the green 

 honeycreeper has become increasingly similar to those of some Tan- 

 gara tanagers, by convergent evolution, because this similarity facili- 

 tates associations with these tanagers, and such associations are usually 

 advantageous to green honeycreepers. If so, this similarity may be 

 considered a form of "social mimicry" (Moynihan, i960). 



(It is possible that green honeycreepers have a slight special inter- 

 specific preference for golden-masked tanagers. If so, this preference 

 would be similar to their preference for plain-colored tanagers in 

 quality, but probably much weaker. Under natural conditions green 

 honeycreepers seem to join and follow golden-masked tanagers rela- 

 tively much less frequently than they join and follow plain-colored 

 tanagers.) 



Green honeycreepers perform relatively few aggressive movements, 

 but sometimes utter many aggressive calls in predominantly tanager 

 flocks. This would suggest that they are sometimes motivated by 

 strong aggressive tendencies in such flocks, but that these tendencies 

 are often partly inhibited. It is probable that they find many of their 

 companions in predominantly tanager flocks quite irritating (although 

 presumably less irritating than other members of their own species) 

 and also very intimidating. Most tanagers are as large as, or even 

 larger than, green honeycreepers, and would be expected to be intimi- 

 dating to the latter. 



The reactions of green honeycreepers to other honeycreepers are 

 rather more varied than their reactions to tanagers. They tend to 

 perform many supplanting attacks upon red-legged blue honeycreep- 

 ers. They may also attempt to join and follow the latter in a 

 "friendly" manner ; but such attempts are relatively very rare, and are 

 probably nothing more than expressions of generalized gregariousness. 



Green honeycreepers do not usually attack red-legged blue honey- 

 creepers as frequently as they attack other members of their own 

 species ; but I have seen them do so in certain special circumstances, 

 when several green honeycreepers and red-legged blue honeycreepers 

 were feeding in the same small tree. The green honeycreepers became 

 particularly aggressive in such circumstances. Their aggressiveness 

 may have been released originally by their proximity to one another ; 

 but they seemed to vent this aggressiveness upon one another and 

 upon the red-legged blue honeycreepers quite indiscriminately. 



The hostility of green honeycreepers toward red-legged blue honey- 

 creepers might be considered a peculiar form of special interspecific 

 preference, much more limited in scope than the special interspecific 



