NO. 5 THE YELLOW-RUMPED TANAGER — MOYNIHAN 21 



accompanied by some raising of the feathers of the chin, throat, and 

 cheeks. "Rounded" Head-ruffling of this type seems to be per- 

 formed most frequently by birds disturbed by the presence of a poten- 

 tial predator. It is frequently associated with Nasal Notes and may 

 be produced by similar motivation, i.e. when the escape tendency 

 is stronger than the attack tendency but the latter is by no means 

 negligible. Part of this pattern, i.e. the raising of the crown feathers, 

 may be strictly homologous with the "Crest-raising" of green-backed 

 sparrows and some other "emberizine" finches (see Andrew, 1961). 

 The other type of Head-ruffling is illustrated by figure 4c. In this 

 pattern the head does not appear to be rounded. When viewed from 

 the side there are more or less distinct peaks at the forehead and 

 nape as well as in the center of the crown. The feathers of the chin, 

 throat, and cheeks also are raised, perhaps more so on the average 

 than in the "rounded" Head-ruffling. This type of Head-ruffling may 

 be called "angular." It occurs during many encounters between males 

 and females but usually not in close association with successful copu- 

 lations. It seems to be characteristic of situations in which both 

 hostile and sexual tendencies are activated simultaneously and are in 

 strong conflict with one another. It may be intermediate between 

 "rounded" Head-ruffling and Head-fluffing. 



The most typical form of Head-fluffing is illustrated by figure 3a. 

 The feathers of the crown are raised to a very considerable extent, 

 but their tips are not well separated from one another. When viewed 

 from the side the head appears to be roughly square or trapezoidal, 

 with one angle at the front of the crown and another at the back of the 

 crown. There is no peak in the center of the crown. The cheek and 

 throat feathers may be raised but seldom or never as much as in ex- 

 treme Head-ruffling. Typical Head-fluffing usually or always accom- 

 panies Dawn Calling, especially Dawn Calling of Hoarse Flourishes or 

 "Kioo" or "Klioo" Notes, and is rare or absent in other circum- 

 stances. A less extreme form of Head-fluffing sometimes accompanies 

 series of "Tzzheet" Notes later in the day (see figure 3b). It seems 

 likely that Head-fluffing is primarily or exclusively an expression of 

 sexual motivation, but not the same sexual tendency (or combination 

 of tendencies) as Crown-flattening. It may have been derived by 

 exaggeration and (increased) ritualization from the more or less 

 square but less "swollen" head-shapes frequently assumed by such 

 species as the silver-billed tanager and the Chlorospingus bush- 

 tanagers during Dawn Calling. 



Yellow-rumped tanagers may have one other purely or primarily 



