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(?) major, (underlined) I               21
                           April 16, 1960
                           Barro Colorado

  Tested M & Hrr a little again.
  I first took Hrr out and let her run on the floor, and then experimented with M who remained in their cage. I couldn't get M to utter anything when handled, or when left completely isolated, but, about 5 minutes after Hrr had been take out of the cage, I went up to the cage and talked to M, in my normal voice - and she responded by uttering a long burst of at least 6 or 7 DN's. Repeated this burst a couple of minutes later when I went up to the cage and spoke to her again. Their DN's seemed to be eventually DN2's (as expected), but I think they were somewhat lower-pitched than they used to be (although still quite whistle-like).
  After all the testing was done, when both birds were back in their cage, M immediately tried to huddle under Hrr, presumably in order to go to sleep. At this time, one of the birds, almost certainly M, also uttered a long burst of DN's. There were DN2's, just like the ones M had uttered earlier in the evening in response to me.
  I couldn't get Hrr to utter anything (?) circumstances.
  Both birds seem to be performing more TVC's more frequently now.  Possibly because David and I haven't been with them much recently.  Tonight I saw Hrr perform a TVC which was much more extreme than any I have ever seen before. Tail lifted considerably higher than in the sketch on Apr. 3, p.17. And M performed the first fairly extreme TVC I have seen her do. (Her TVC's are still less extreme than those of Hrr on the average - and less frequent.
  After I had been playing (?) about with both birds for quite a