NO. 7 FLOCKS OF NEOTROPICAL BIRDS — MOYNIHAN III 



black-and-yellow tanagers (Chrysothlypis chrysomelas) hepatic 

 tanagers (Piranga flava), and various small flycatchers and (winter- 

 ing) warblers. Such flocks seldom or never include more than a single 

 individual, pair, or family group of any given species at any given 

 time. 



Unlike the other mixed flocks discussed above, these mixed flocks 

 on Cerro Campana do not seem to be specialized societies. They 

 appear to be essentially casual aggregations of birds that happen to 

 be feeding more or less together in the same area but are not very 

 strongly attracted to one another. Clear-cut interspecific following 

 and joining reactions are relatively rare in such aggregations. Even 

 the blue tanagers and the green honeycreepers do not join and/or 

 follow individuals of other species very frequently on Cerro Cam- 

 pana. (They might join and/or follow one another very frequently 

 if they had more chances to do so; but both species are rare in 

 these montane forests.) None of the primarily montane species com- 

 monly occurring in these aggregations seems to have any definite 

 special interspecific preference for any other species, and most of 

 the associations between these species seem to be relatively brief. 

 The species of the mixed flocks on Cerro Campana are also very 

 diversely colored and do not seem to have developed any special type 

 of plumage to facilitate their roles in the mixed flocks of this area. 



In general, the mixed flocks of the montane forests on Cerro Cam- 

 pana are most reminiscent of the lower-altitude mixed montane bush 

 flocks on the Volcan de Chiriqui, without the nuclear species which 

 usually or frequently occur in the Chiriqui flocks. 



RAMPHOCELUS FLOCKS 



Different species of Ramphocetus, which usually do not form very 

 close associations with birds of most other genera, do tend to asso- 

 ciate with one another rather closely in some areas and habitats where 

 their ranges overlap. I have seen associations between two different 

 pairs of Ramphocelus species. 



Mixed flocks of crimson-backed tanagers and yellow-rumped 

 tanagers occur in many areas in central and eastern Panama. I have 

 observed them at rather long intervals between March 1958 and 

 November i960 in the Canal Zone, near Maria Chiquita on the Atlan- 

 tic coast of central Panama, and in Darien. 



Mixed flocks of silver-billed tanagers (R. carbo) and black- 

 throated tanagers (R. nigrogularis) were observed for a few days 



