90 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I43 



tanagers for longer periods of time than they do individuals of other 

 species, and sometimes follow them at greater distances than they do 

 individuals of other species. I have seen a pair of yellow-thighed 

 finches in low shrubbery follow a flock of brown-capped bush-tanagers 

 moving through trees above the shrubbery for several hours at a time, 

 and repeatedly follow the same flock on several successive days, in 

 spite of the fact that the brown-capped bush-tanagers were usually 

 30 to 50 feet above and approximately 20 feet ahead of them. 



It is often particularly clear that yellow-thighed finches and brown- 

 capped bush-tanagers are not obtaining extra food by associating with 

 one another. In the case of the association cited immediately above, 

 for instance, the brown-capped bush-tanagers were usually feeding on 

 insects while the yellow-thighed finches following far below and 

 behind them were usually feeding on fruit and other vegetable matter. 



Yellow-thighed finches usually do not react to brown-capped bush- 

 tanagers that are more than 50 feet above them, or to individuals of 

 most other species that are as much as 30 feet above them. Thus they 

 have almost no contact with individuals of those species of the mon- 

 tane bush alliances that usually remain in or near the tops of tall trees. 



As a general rule yellow-thighed finches tend to follow and join 

 individuals of all other species more frequently when the latter are 

 being vocal than when they are silent. 



Yellow-thighed finches are gregarious among themselves in much 

 the same way and to approximately the same extent as sooty-capped 

 bush-tanagers and black-cheeked warblers. Individual pairs and fam- 

 ily groups seem to defend individual territories throughout the year 

 (see below). Rather surprisingly, however, yellow-thighed finches 

 have many characters that are strongly reminiscent of characters of 

 other species that are more highly gregarious among themselves. 



Yellow-thighed finches are remarkably conspicuous. Their gen- 

 erally black plumage is usually easy to see against a background of 

 shrubbery. Their yellow thighs seem to be flash patterns, which func- 

 tion in the same way as the bright wing and/or tail patches of many 

 other gregarious species. They hop very frequently, and their yellow 

 thighs are revealed very conspicuously when they hop. They are not 

 very shy, and are much less skulking than the other bush finches, e.g., 

 the species of the genus Atlapetes, which may be their nearest rela- 

 tives. They usually move in a peculiar floppy, clumsy-looking way, 

 which tends to attract the eye of any observer. They are also noisy. 

 They usually utter one or more types of call notes almost constantly 

 as they move through the shrubbery. Whenever one bird of a pair 



