56 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I43 



even before the green honeycreeper gets very close. They may have 

 learned that green honeycreepers are often aggressive. In many cases, 

 when an individual of another species retreated before a green honey- 

 creeper in this way, the incident could not be classed as a clear-cut 

 case of either joining or supplanting, according to the criteria used 

 in compiling the accompanying tables. 



As a general conclusion, green honeycreepers may be said to have 

 two contradictory effects upon mixed flocks. They may tend to in- 

 crease the cohesiveness and attractiveness of a mixed flock and/or 

 tend to disrupt the flock. They may produce these effects successively 

 or simultaneously. The disruptive effect of green honeycreepers is 

 not, however, always as strong as might be expected. The increased 

 calling and rapid movements provoked by, or accompanying, sup- 

 planted attacks and other aggressive patterns by green honeycreepers 

 may tend to attract other birds in much the same way as do mobbing 

 reactions. 



SHINING HONEYCREEPER 



Shining honeycreepers were not observed very frequently during 

 the present study. They are common on Barro Colorado Island, 

 but seldom conspicuous around the laboratory clearing. When they 

 were seen, their behavior was more or less reminiscent of green 

 honeycreepers. 



Their social behavior apart from mixed species flocks in central 

 Panama seems to be quite remarkably similar to that of green honey- 

 creepers. Shining honeycreepers have much the same range and types 

 of display patterns 9 as green honeycreepers, and also tend to be very 

 aggressive, and therefore only very slightly gregarious among 

 themselves. 10 



In mixed flocks, however, the social role of shining honeycreepers 

 seems to be less important than that of green honeycreepers. Shining 

 honeycreepers do tend to join and follow individuals of other species, 

 at least occasionally, but they do so relatively much less frequently 

 than do green honeycreepers. All or most of their interspecific joining 

 and following reactions seem to be expressions of generalized gre- 

 gariousness. As far as I could tell, they do not have the special inter- 



9 The term "display" will be used throughout this paper to include all vocal 

 patterns and all movements and postures that appear to have become specialized 

 to subserve a signal function. 



10 Slud (i960) says that shining honeycreepers are rather strongly gregarious 

 among themselves in part of Costa Rica; but this is definitely not true of 

 the shining honeycreepers of central Panama. 



