NO. 5 THE YELLOW-RUMPED TANAGER MOYNIHAN 3 1 



stances. There is some evidence that the "Tsit" Notes of these silver- 

 billed tanagers are "Short Hostile Notes" and homologous with the 

 Nasal Notes of crimson-backed tanagers. This may also be true of 

 the "Tsit" Notes of Peruvian black-throated tanagers. If so, such 

 notes are not strictly homologous with either the "Tsit" Notes of the 

 captive yellow-rumped tanager on Barro Colorado Island or the 

 "Tsit" Notes of the captive orange-rumped tanagers in the New York 

 Zoo. (I might add that none of the black-throated tanagers observed 

 near Iquitos or in the New York Zoo uttered any notes which sounded 

 more like the Nasal Notes of other species.) 



In any case it is possible that the resemblance between the "Tsit" 

 Notes of the black-throated tanagers and silver-billed tanagers near 

 Iquitos is an example of some kind of mimicry. This resemblance 

 may facilitate associations between the two species, and such associa- 

 tions may be advantageous (to one or both species) in some circum- 

 stances. (It may be significant that the Short Hostile Notes of 

 silver-billed tanagers in Trinidad, where black-throated tanagers are 

 absent, are rather different in sound.) It is equally possible that the 

 similarities between the Nasal Notes of yellow-rumped tanagers and 

 crimson-backed tanagers facilitate associations between these two 

 species. 



The vocalizations of the captive black-throated tanager in the 

 New York Zoo were rather puzzling. It uttered Rattles quite like those 

 of the orange-rumped tanagers. It also uttered "Tsit" Notes, softer 

 and less metallic than those of the Iquitos birds, by themselves alone 

 and immediately before and/or after Rattles. These "Tsit" Notes 

 may have been strictly homologous with those of the orange-rumped 

 tanagers. (This particular black-throated tanager may also have been 

 imitating, or have learned part of its repertory from, the orange- 

 rumped tanager in the same aviary. ) 



GENERAL COMMENT 



It may be useful to emphasize certain aspects of the display 

 behavior of the genus Ramphocelus as a whole. 



1. There is no display or combination of displays that can be 

 considered diagnostic of the genus, i.e. that is performed by all the 

 species of the genus and not by species of other genera. 



2. All or most of the displays performed by some but not all of 

 the species of Ramphocelus are also found in some species of other 

 genera. In most cases the homologous patterns of species of other 



