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Tangara, Feb. 1, 1958, II

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of most of these disputes was that they were quite silent throughout, as well as lacking ritualized postures and movements.

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The only sounds I heard during any of these disputes were a few CN’s and TrCN’s during some aerial chases, and (possibly) a few rather thin and relatively long & weak “Treeet”s, during one of the chases (this sounded as if it might be a distinctly different call, but I am not absolutely sure which bird or birds gave it.

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This sort of behavior would suggest that the aggressiveness within a flock is not suppressed as such, but it is controlled by the fact that the attacked bird usually retreats immediately, (and the relative rarity of ritualized displays is undoubtedly connected, in one or more ways, with this.

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Now two long continued fights, in air, birds tumbling all over and falling down to ground. Both times the fight was accompanied by loud, prolonged TrCN. No sign of other ritualization.

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I think perhaps that it would be safe to say that fighting has increased in the flocks of Plains during the last 2-3 weeks. Approximately since the beginning of the dry season, in fact. Why?

Tangara, I

February 2, 1958
Barro Colorado

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Well! Sex rears its ugly head - at last!!! I located a pair of Plains when a copulation attempt was in full swing. The [female symbol] was in a Soliciting Posture (SP) and the [male symbol] attempted to mount 2 or 3 times. All their attempts were very brief