NO. 7 FLOCKS OF NEOTROPICAL BIRDS — MOYNIHAN 93 



of sooty-capped bush-tanagers is usually also the territory of a single 

 pair or family group of yellow-thighed finches. Thus whenever a 

 mixed flock moves over a gap in the shrubbery in this area it tends 

 to provoke a dispute among both sooty-capped bush-tanagers and 

 yellow-thighed finches. Similar reactions probably occur among indi- 

 viduals of the same and other species associated with mixed mon- 

 tane bush flocks in other areas on the Volcan de Chiriqui ; but they 

 are usually or always less conspicuous. 



YELLOW-THROATED BUSH-FINCH 



Yellow-throated bush-finches seem to occur in mixed montane bush 

 flocks much less frequently than either of the bush-tanagers, the 

 black-cheeked warblers, or yellow-thighed finches, in spite of the fact 

 that they are common over a wider range of altitudes than any of 

 these latter species. They do, however, follow and join individuals 

 of other species occasionally. They are most likely to follow and join 

 yellow-thighed finches, probably at least twice as often as they fol- 

 low and join individuals of any other species frequently associated 

 with mixed montane bush flocks. 



As yellow-throated bush-finches live in thickets and low shrubbery, 

 it might be supposed that their occasional associations with yellow- 

 thighed finches were purely coincidental ; but there is some evidence 

 that a slight but definite special interspecific preference is also in- 

 volved. Yellow-throated bush-finches follow and join yellow-thighed 

 finches relatively more frequently than do chestnut-capped bush- 

 finches (Atlapetes brunnei-nucha) or large-footed finches {Pezopetes 

 capitalis), which also occur in thickets in some of the same areas on 

 the Volcan de Chiriqui. 



Yellow-throated bush-finches are conspicuously colored, but shy, 

 skulking, and quiet. They seem to be followed and joined by indi- 

 viduals of other species less frequently than they follow and join indi- 

 viduals of other species. 



FURNARIIDS 



A very large proportion of the species of the family Furnariidae 

 (sensu lato, including the tree-creepers or dendrocolaptids) are fre- 

 quently associated with mixed flocks of one type or another ; but the 

 red- faced spinetail was the only species of furnariid studied in detail 

 during the present investigation. 



Red-faced spinetails usually occur moderately high in trees, al- 



