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8

Puerto Armuelles, July 18, 1967, III


with this group

Several more bursts high pitched sounds (a variety) a few seconds later. I can't see the animals well at the time. But again I think that the sounds must be used intra-specifically.

These sounds continue off and on for some time. Eventually it becomes obvious that the majority are "Tsit" notes and Trlls. Probably quite hard, mechanical Trlls. I think that the "twittering" effect noted so frequently here is deceptive. It may occur only when two individuals are uttering Trlls simultaneously but "out of phase". I still can't see what is provoking these sounds. Animals are very active _ but not making definite progress in any one direction. Are they chasing one another and/or disputing over food? (As far as I can tell, they are all adult or sub-adult.)

In any case, it seems evident that the animals here are less silent than I expected (or originally thought). It is only that many of their sounds are particularly difficult to notice and to locate.

Eventually, the rain becomes heavier. And animals start to move off. Over our heads still uttering high pitched sounds quite frequently. At this time, it is evident that all or most of the "Tsit" type notes are directed, or redirected, toward us.

ADDITION: Annette tells me that she saw an apparent incomplete copulation attempt in group seem first this morning. This certainly is not same incident seen by Marcel (later).