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80 

Rhamphocelus, Jun. 16, 1961, V.       

type of note I called "MCN." I think that they are probably relatively more aggressive than the Wh MCN's (see the incident described on Jan. 30, 1958 p.5). I shall call these notes "Stacc MCN's."

Third, the HAC-MCN's. Like the Wh MCN's but louder, more rasping. Shading off into HSci-type notes. These are presumably produced by higher intensity motivation than the Wh MCN's but their relative aggressiveness may be the same as in the Wh MCN's (i.e. both types of notes may be produced when the attack & escape drives are nearly balanced). I shall call these notes "HAC-MCN's".

The ACNs of the Yellow-rumps seem to be slightly but definitely thinner and less nasal than the ACNs of the Sangres. 


Rhamphocelus, I 
          
June 21, 1961
Barro Colorado

Watching the captive pair of Sangres 5:50.

Male uttering "dawn song" just as on Jan. 16. Then flies to perch beside female, assumes some sort of Pre-cop Posture (with Wass); but the female flies away immediately. (It is still too dark to see anything very well).

Male is now (6:00 a.m.) Very active. Flying energetically and steadily from perch to perch. Pausing briefly at each place to utter "Keeyoo" song. Song composed of "Keeyoo"s and "Keew"s with an occasional single, hard, loud rattling "Kraa". Every once in a while, the male flies to the female and assumes an indication of a slight Pre-cop Posture. Finally just BL & TU, nothing more.

Female just sits quietly, without moving, all this time. But she may utter Wh MCN's when the male comes very close.