SP/Myers 1973 Calidris melanotos Grid 9 (Farmhouse Puddle), Estancia Wildland, 35 KmS of Juancho by road, Pucia de Buenos Aires, Argentina 17 December (cont'd) A posture. However, none of the other Pectorals evidence a territoriality. Watching one that just landed within 1m of another (within 1.5m of a third) - absolutely no aggressive display in this tried. Many of the birds foraging, a few preening + washing. Watching A still within 6" of another, bowed over feeding. I can barely see him because the grass is just about the height of his back and there are slight depressions. Watching two others in (3-4, 0-1) unit. they have been foraging together (1'-3') for 1 min at that distance. 18 December 0015 - in the same area I saw aggression yesterday, this is a Pectoral behaving as if he has a territory. Several supplanted by Pectorals in 5 minutes, plus one WR chasing, (Molina)2 Grid 3 (500m N of Farmhouse), Estancia Wildland, Pucia de B.A., Argentina grid counts of Pectorals may not be complete because the birds are all able to disappear in the grass. Watching a single Pectoral: 1:45 chasing another Pectoral. The first bird was in the center of (2,3) unit (5x5 section) and flew to the corner of (4,2) - where (4,2) bids (3,2) in order to eject the other Pectoral, a distance of 7.5m. (foraging) For the same Pectoral: every 5 sec sample whether his head is in an up or down position (time = 1342): down, down, down, down, up, down, up, up, (making noise), down, down, down, up, up, up, up, up, up, up, up. At this point he stopped foraging to preen, so I stopped sampling [Total: 9 down, 12 up]. Within the sampling period the bird was foraging; between each sample his head may have changed from up to down several times. 1440 - just finished second sample of 3A and 3B. Shan the definite uniqueness that in 3B there are a slew of territorial Pectorals, spread out ~1/25x25m unit. I can hear territorial call (at least what I think is); [illegible] a typical crump note emitted with the much exaggerated bill down, just before flying a supplant. Watched 2 supplanted: the second one > 300 (1.5) unit, started from (0,1) had wandered in a J-shaped path to (0,1) - distance of over 10m. Another individual: one landed in (4,4) and one in (7,2) [illegible] & started [illegible] - I could both hear see noise-maker. The intruder around closer. The noise-maker spread his bill wide (couldn't hear call), flew toward the intruder, and landed where the intruder had been (also flew curvey). To see that flew away. I think is territorial in (4,2). Following this interaction, the (4,2) bird began feeding and moving away from the site of the interaction, remaining very alert. The supplantor continued to move toward (4,2) but stopped short of reaching the bird he had before chased.