NO. 5 THE YELLOW-RUMPED TANAGER MOYNIHAN 23 



Rattles and/or Muffled Rattles. The swoops of the males brought 

 them very close to the females but not, I think, into actual contact. 

 In four out of the five cases the female reacted to the swoop by flying 

 away very rapidly. In two of these cases the male followed and a long 

 twisting chase ensued. In the other two cases the male turned away, 

 landed on a perch, and relaxed. After one swoop both birds landed 

 in a tree about ten feet apart from one another. The male uttered 

 pure Rattles and/or Thin Rattles, facing the female, while the female 

 did silent Gaping in the direction of the male. Then the female flew 

 away and the male did not follow. This swooping behavior of male 

 yellow-rumped tanagers is very reminiscent of the Pouncing of male 

 song sparrows (Melospiza melodia) described by Nice, 1943, but 

 seems to be performed much less frequently. Although the accom- 

 panying Rattles indicate that some hostility is involved, the pattern 

 may be primarily an attempt at forced copulation or rape. 



Turning-away is another apparently ritualized pattern which seems 

 to be performed only by adult males in the presence of females at the 

 height of the breeding season. It is most common immediately after 

 a male joins or is joined by a female. The two birds usually face one 

 another when they first come together. But then the male may 

 deliberately turn away and stand for at least a few seconds rigid 

 and motionless with his tail pointing directly toward the female. In 

 this position the male usually performs typical Back-ruffling (the 

 ruffling may appear even before he turns) and holds his head 

 fairly low (in any case, his head and foreparts must be more or less 

 hidden from the female). His tail may be approximately horizontal 

 or slightly raised. Sometimes it is fanned. Figure 2c shows a posture 

 of this type. The male usually falls silent as soon as he turns away 

 from the female. Only once did I hear a male utter a single note, 

 a Hoarse Flourish, while he stood motionless. 9 



Two apparently successful copulations were observed. Both 

 occurred early in the morning, approximately one half hour after 

 dawn. The birds involved were not the same in the two performances. 

 One performance began when the male flew into a tree where the 

 female was already perched. He perched on a branch about ten 



9 Once a male was seen to stand in a slightly more distinctive posture after 

 Turning-away. The wings were drooped as during typical Back-ruffling, but 

 the yellow feathers of the lower back and rump were not erected to any ap- 

 preciable extent (see figure 2b). As this was the only time that a male was 

 ever seen to perform conspicuous wing-drooping without ruffling of the yellow 

 feathers, in any circumstance, the performance may have been nothing more 

 than an individual aberration. 



