20 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I49 



repeatedly threatened and supplanted by the male of the pair. The 

 combination of a hunched posture with Belly-fluffing is very reminis- 

 cent of the "Fluffed Hunched Posture" of green-backed sparrows and 

 the "fluffed postures" of many other passerines (Hinde, 1955). The 

 latter seem to contain very strong escape components and function 

 as appeasement. Perhaps the Belly-fluffing of yellow-rumped tanagers 

 is also an expression of the escape tendency. (Female yellow-rumped 

 tanagers may ruffle the feathers of the breast and belly in Bill-up 

 Tail-up Postures in sexual situations [see page 24] but this probably 

 is not strictly equivalent to the Belly-fluffing of males.) 



Crown-flattening is less conspicuous than the feather-raising pat- 

 terns and easily overlooked in the field, but it is certainly combined 

 with a variety of other displays, including Thin Rattles, Bill-up Tail- 

 up patterns, and "Turning-away" (see page 23), in addition to Belly- 

 fluffing and Back-ruffling (see figures 2b, 2d, 4a, 4b, and 5a). 

 There is no very obvious "common denominator" to all the situations 

 in which Crown-flattening occurs. In almost all cases, however, it is 

 shown by males in close association with (known or presumed) 

 females at the height of the breeding season, and it can occur imme- 

 diately after copulation. It may be an expression of some sexual 

 tendency or tendencies (or a particular combination of sexual and 

 escape tendencies). 



All yellow-rumped tanagers seem to perform Tail-fanning that is 

 very similar to the Tail-fanning of crimson-backed tanagers. Like the 

 latter it is performed in such a very wide variety of situations that it is 

 particularly difficult to interpret. Perhaps it is an indication of an 

 activated escape tendency. If so it probably is performed when the 

 escape tendency is weaker and/or in less conflict with other tendencies 

 than when all or most Belly-fluffing is produced. It is frequently 

 performed by individuals who are not performing any other ritualized 

 displays (except Flicking movements) at the same time. 



The patterns involving raising of the head feathers are much more 

 conspicuous than either Crown-flattening or Tail-fanning but perhaps 

 equally problematical. 



There may be two slightly different types of Head-ruffling. In one 

 type all the feathers of the crown are raised to a more or less extreme 

 degree. The tips of all the crown feathers are well separated from one 

 another. When viewed from the side the general effect is exactly the 

 same as in the Head-ruffling of orange-rumped tanagers, illustrated 

 by figure 4d. The top of the head appears rounded with the highest 

 point near the center of the crown. This is usually, perhaps always, 



