12 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I49 



violent dispute (including many contact fights) between two adult 

 males at the height of the breeding season. And once I heard a 

 bird in female or juvenal plumage (probably an adult female) utter 

 a single Muffled Rattle immediately before feeding another bird in 

 similar plumage (presumably a juvenile). It is evident that Muffled 

 Rattles are very high intensity patterns. They seem to intergrade with 

 both typical pure Rattles and typical Thin Rattles. Possibly they are 

 somewhat heterogeneous. Some Muffled Rattles may be nothing 

 more than unusually soft pure Rattles, while others may be nothing 

 more than unusually soft Thin Rattles. (All the extreme Muffled 

 Rattles are so soft that I could never tell which of the louder Rattle 

 patterns they most resembled in pitch). If the Muffled Rattles are 

 heterogeneous in this way, then some may be purely hostile, produced 

 when the attack tendency is strongly predominant over the escape 

 tendency but both are stronger than during typical pure Rattles, while 

 others may be partly hostile and partly sexual, produced when the 

 relative strength of the hostile and sexual tendencies is the same as in 

 typical thin Rattles but the actual strength of all the tendencies is 

 greater. 



Some or all of the Muffled Rattles of yellow-rumped tanagers may 

 be strictly homologous with the Muffled Rattles which are uttered by 

 male brown-capped bush-tanagers approaching females and imme- 

 diately before copulations. 8 



8 Two other vocal patterns of yellow-rumped tanagers appear to be set some- 

 what apart from the mass of intergrading patterns described above. 



One captive adult male was heard to utter many "Tsit" Notes. They were 

 much softer and shorter than typical "Tzzheet" Notes. They were uttered singly 

 or repeated at irregular intervals (i.e. they were never organized in regular 

 series like Dawn Calling notes). The male uttered these notes after being in 

 captivity, in the same cage, for over a year, whenever he saw a human being 

 in the distance. If the human came closer he usually began to perform escape 

 movements or intention movements and to utter typical Nasal Notes instead of 

 the "Tsits." Thus it would appear that the "Tsit" Notes were low intensity 

 alarm patterns. Presumably they were produced when the escape tendency 

 alone was activated or (more probably) when both hostile tendencies were 

 activated simultaneously and escape was much stronger than attack but both 

 tendencies were weaker than when Nasal Notes are uttered. These "Tsit" Notes 

 were much too weak to be heard in the field. Thus I do not know if they are 

 really typical of the species or not. If so they may be strictly homologous with 

 the soft "Tsip" or "Chik" alarm notes of green-backed sparrows. In any case 

 it seems very unlikely that they are closely related to the louder but otherwise 

 similar sounding "Tsit" notes of either Chlorospingus species or some other 

 species of Ramphocelus (see pages 30 and 31). 



One wild male in typical adult plumage was observed to perform something 

 which looked like "silent song." He sat for several minutes opening and 



