S.P. Myers 1974 Tryngita subroficollis 61 Grid 17B, Tower, (118) region, Estancia Wieland, 35 km. S. of Juancho by road, Pto de Madariaga, Provincia de Buenos Aires, Argentina 22 November had to have gone somewhere! 0840 - cap display by 01-16b (the wing of the bird, when cupped, comes forward as far as they go out. Definite curvature of the wing, not simply a bend at the wrist. The head is not up, but rather the bill was pointed toward the head of the other bird. 0845 - golden chard (buffic) buffic winged up. 0908 - an invasion, sheep too. The situation on the grid appears to be returning to normal - a heavy emphasis on territoriality. 0945 - a bird by lower corner of 16b has been maintaining a territory of sorts. It just finished helicopter supplantation. Usually, when a bird enters its territory, it will feed directly toward the bird + achieve a supplantation by 'working' it out with incredible but slow pressure. No overt intense aggression, but instead a parallel feeding until potential intruder departs. The ten bird returns toward center. 0948 - we have been following the 0945 bird. It entered (0,0) of 16b, at which time 01-16b came over, beginning to raise its head by neck stretching at 8m distant. 01-16b fed intermittently, continuing directly toward the intruder's head, raising occasionally + walking increasingly in increasingly more rapidly. The intruder began reversing its direction, in fact walking directly away from 01-16b, until it reached him and during its retreat regularly but with low frequency, showing a tail down. When it reached 1m inside the (1,0) unit of 16b, crowded, tucked bill, and 01-16b, which by that time was in middle of (0,1) unit, began to turn around + fed away. It never reached within <5m of the other bird. Within 30 sec the other bird was out of the crowd + had begun to feed away. The most striking thing about this interaction was its subtlety. Unless we had been monitoring the positions of these birds for some time it would have appeared to have been insignificant, instead of the border interaction between two neighbors that it actually was. A very space-specific encounter. Crowds, tail downs + turn arounds were all positionally consistent with our understanding of the spatial array of these 2 birds' territories.