28 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I49 



abbreviated form (i.e. coded with maximum efficiency). But they 

 also have certain disadvantages. They may be difficult to read or 

 decipher because of their complexity or easily confused with other 

 (related) vocal patterns, simply because they are not always very 

 distinctive in sound (they must resemble the other notes between 

 which they are intermediate) . These disadvantages may be avoided if 

 the intermediate vocal patterns are usually or always accompanied 

 by other information which will make their meaning clear. Thus 

 among primates the species or classes of individuals that utter many 

 intermediate or intergrading vocal patterns are diurnal and/or 

 highly gregarious and/or tend to remain in very close contact with the 

 other members of their own family group. Any individual of these 

 species or classes hearing calls or notes from another individual of the 

 same species will usually perceive visual, olfactory, or tactile signals 

 or other stimuli from its companions and/or receive visual or olfac- 

 tory clues from the physical environment at the same time. These 

 visual, olfactory, or tactile aids should enable the receiving individual 

 to grasp the meaning or significance of any vocal pattern, even when 

 the latter is difficult to decipher or ambiguous in itself. (This aspect 

 of vocalization in primates is discussed in more detail in Moynihan, 

 1964.) It is possible that the different types of vocal repertory in 

 different species of tanagers are adaptive in much the same way as 

 the corresponding types of repertory in primates. Perhaps yellow- 

 rumped tanagers can "afford" to utter many intermediate notes simply 

 because they are usually within sight, as well as sound, of their most 

 important social companions, competitors, and rivals throughout the 

 year. They must receive visual clues and stimuli with a larger propor- 

 tion of the vocalizations to which they should respond than do indi- 

 viduals other species which are more isolated during the breeding 

 season. 



SOME PATTERNS OF ORANGE-RUMPED TANAGERS 



Two adult male orange-rumped tanagers in the New York Zoo 

 were observed briefly during a few days of October 1958. They were 

 labeled "flammigerus," and probably were hybrids between /. 

 flammigerus and /. icteronotus. They were kept in separate aviaries. 

 There were many other birds of different species in both aviaries, 

 including other species of Ramphocelus. Both orange-rumped tan- 

 agers performed an appreciable number of displays and related or 

 associated patterns. They became engaged in disputes with a variety 

 of other species. They even performed a few partly sexual patterns. 



