J.P. Myers 1974 Journal Grid 17B, Townen (1,18) region, Estancia Medaland, 35 kms. of Juvanelo by road, Ptdo. de Madariaga, Provincia Bs. Aires, Argentina 22 November samples during which the birds were off the grid for one reason or another. In addition, (puffy territories) had expanded to a point when several territories present 20 November had been devoured, leaving fewer territories once impinging upon the area encompassed by the grid. In fact, there were 13 territories vigorously defended during the morning (see Tryngites spacet). The %TB calculation yielded a value of 97% !!! I have considerable confidence in that figure being either so, or higher. During the morning, following an unusually long spoke during which the birds may have gone to the Arrayo, territories ruled the grid. Then in early afternoon, after the birds went to the Arrayo, territories were less vigorously maintained in some areas, the' they were kept up in others. I obtained a nice series of samples following a spoke induced by the overflight of a Swainson's hawk, (taking points for 3 successive 2min intervals). We remained somehow on the tower until 1900, by which time all but one of the birds had left, although Flur. remained as would be expected. During most of the day we have data which will allow frequency of aggression to be determined. Weather remained clear throughout most of the day. Temperature rose to ~25°C. Wind grew to a moderate NW wind and remained steady until late afternoon. Linear grid subunit 5 (11,16), Arroyo Chico, Estancia Medaland, Ptdo.de Madariaga, Provincia de Buenos Aires, Arg. 25 November down from camp along Arroyo Chico looking for concentrations of LWR with the intent of locating an area for calculating %TB, etc. The low level of water surprised us - yesterday evening it rained ~7 mm, and such downpourings have not, in the past, receded so quickly as this one has. This morning there was no current. But it was obvious from the water line that within the past 48 hours water had been up ~80-100 cm, 10-15 cm, at least freely. Probably the series of days with continuous, strong W and NW winds has had considerable drying effect, serving not only to increase evaporation but also