50 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I43 



in mixed flocks. They are reduced to the role of occasional and very 

 temporary associates of the mixed flocks as long as they remain very 

 closely attached to their nest sites. 



It has already been mentioned that individuals of many species tend 

 to associate with mixed flocks less frequently during the breeding 

 season than during the nonbreeding season ; but the palm tanagers 

 observed in central Panama tended to sever their connections with 

 mixed flocks more nearly completely than all or most individuals of 

 all or most other species. This may have been partly due to the fact 

 that their nesting sites were more often isolated. The favorite nesting 

 sites of palm tanagers in central Panama are in coconut palms ; and 

 many or most of the coconut palms in this region are quite isolated 

 from other tall trees. 



In any case, the differences between the interspecific social reactions 

 of palm tanagers during the breeding and nonbreeding seasons seem 

 to be greater, on the average, than the differences between the corre- 

 sponding reactions of any other species of the blue and green tanager 

 and honeycreeper alliance. 



The behavior of the palm tanagers at Frijoles in July and August 

 i960, when they were associated with mixed flocks much less fre- 

 quently than individuals of many other species, was a good example 

 of social isolation persisting immediately after the breeding season. 

 All or almost all the palm tanagers in the Frijoles area seemed to have 

 finished breeding before observations were begun in July i960; but 

 many of them were still in family groups and still more or less strongly 

 attached to nest sites in isolated coconut palms or pylons. 



BLUE TANAGER 



The role of blue tanagers in mixed blue and green tanager and 

 honeycreeper flocks is very similar to that of palm tanagers, but less 

 unbalanced and probably less important, in most circumstances, and 

 more nearly uniform throughout the year. 



Blue tanagers tend to join, follow, and supplant individuals of many 

 other species ; but they do so relatively less frequently and less rapidly 

 than palm tanagers in most environments. As they are also attractive 

 to individuals of other species in much the same way as palm tanagers, 

 they are more often joined and followed by individuals of other 

 species than are palm tanagers in most environments. They still, 

 however, tend to join and follow individuals of other species more 

 often than they are joined and followed by individuals of other species. 



The only species that tends to join and follow blue tanagers very 



