"behavior of either one or "both species is not influenced "by the presence or prox- 

 imity of the other). 



The general social behavior of Panamanian Buff- throated Saltators is 

 strikingly different from that of Panamanian Streaked Saltators in one important 

 respect. The Buff- throated Saltators of this region are not openly very gregarious 

 among themselves. Individuals of different pairs or family groups do not usually 

 join or follow one another in a M friendly" manner, or associate with one another 

 in flocks. But territorial neighbors do approach one another with some appreciable 

 frequency. (This must be an "intrinsic* 1 difference between the two species, as 

 populations of the two species seem to be approximately equally dense in many 

 areas of central Panama. ) As far as I could tell, all or most of the encounters 

 between neighboring Buff- throated Saltators are largely or completely hostile. 

 Panamanian Buff- throated Saltators certainly perform many more overtly hostile 

 behavior patterns than Streaked Saltators in the same areas. They seem to be 

 particularly likely to perform many conspicuously aggressive , such as 



A 



supplanting attacks and chases. 



The account of Costa Rican Buff- throated Saltators in Skutch ( op . pit. ) 

 would suggest that their general social behavior is at least very similar to that 

 of the Panamanian birds. But Skutch also says that Carriker and others found 

 Buff- throated Saltators in small flocks in some parts of Central America. It is 

 possible, therefore , that gregarious tendencies are among the factors that cause 

 Panamanian Buff- throated Saltators to approach one another, even when the 

 approaches are not obviously friendly. 



Panamanian Buff- throated Saltators may be associated with individuals of 

 other species, of other genera, somewhat more frequently than are Streaked Saltators 

 (Moynihan, 1962a) $ but this may be largely due to the fa^t that other* species, 

 especially those species which form mixed flocks anion* themselves, are more common 

 in the trees preferred by Buff- throated Saltators than in the lower vegetation 

 preferred by Streaked Saltators. 



