84 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I43 



which were obviously provoked by and directed toward a silent yellow- 

 thighed finch some yards away. This reaction was presumably an 

 even more extreme case of "overflow." 



Brown-capped bush-tanagers also seem to join and follow yellow- 

 thighed finches slightly more frequently than they do individuals of 

 any other species ; but this may be due to the fact that they are more 

 often in closer proximity to yellow-thighed finches than to individuals 

 of other species, as a result of the behavior of yellow-thighed finches 

 (see below). 



THE SOOTY-CAPPED BUSH-TANAGER 



The sooty-capped bush-tanager is very similar to the brown-capped 

 bush-tanager in general activity and methods of feeding as well as 

 display patterns. It was seen in low shrubbery relatively more fre- 

 quently than brown-capped bush-tanagers on the Volcan de Chiriqui ; 

 but this may have been largely or completely due to the fact that there 

 were fewer tall trees in most of the areas where sooty-capped bush- 

 tanagers were studied than in most of the areas where brown-capped 

 bush-tanagers were studied. 



It is perhaps remarkable, therefore, that sooty-capped bush-tanagers 

 are much less gregarious among themselves than are brown-capped 

 bush-tanagers. They seldom or never form flocks larger than a single 

 family group of a pair of adults plus their most recent brood of young. 

 Each pair or family group seems to defend its own particular terri- 

 tory throughout the year, including the breeding season. 



Sooty-capped bush-tanagers also seem to play a less important role 

 in mixed flocks than brown-capped bush-tanagers. They are joined 

 and followed by individuals of other species more often then they 

 themselves join and follow individuals of other species, and the actual 

 frequency with which they are joined and followed is usually quite 

 high ; but they are certainly joined and followed by individuals of 

 other species relatively less frequently than are brown-capped bush- 

 tanagers. There are also some indications that sooty-capped bush- 

 tanagers may join and follow individuals of other species relatively 

 (but probably not actually) more frequently than do brown-capped 

 bush-tanagers. 



As in the case of the brown-capped bush-tanagers, the vocalizations 

 of sooty-capped bush-tanagers seem to be more attractive than their 

 movements to individuals of other species. They probably do not utter 

 calls as frequently, on the average, as do brown-capped bush-tanagers, 

 and they are sometimes almost completely silent for several minutes 



