JPM Myers 1973 Calidris fuscicollis 500 m W of Farmhouse, Estancia Medeland, Helderberg, 35 km S of Juancho, Provincia de B.A., Argentina 5 December a flock of ~100 cWR along the NW side of a pond created recently (yesterday + last night) in the rain. The pond is open grass, with a few areas of damasquillo. Snacks are on the surface, being blown by the wind. There are at least 4 birds engaged in something like territorial behaviors: the 4 were spread out along a 15' stretch of pond, near the edge where the are small (6" diameter) islands of grass sticking above the water. Each bird appears to be a supplant intruder. I can predict accurately for one bird that I have been watching for x15 min when it will begin to behave aggressively toward a neighbor. It has exclusive use of the small area in which it is feeding. The supplanting behaviors appears to be of varying intensity. Most common is an upright posture with modularity extended well down, where the bird wedges on a easily recognizable "ach ach ach ach..." the bill is opened remarkably wide for the production of this sound. The bird flared its body did this behavior to both neigh- bors feeding nearby as they approached a slight (4") channel separating the territories, and to other cWR flying overhead. Not! to a Microspalax that went by. Secondly, the bird goes with a crowd, with the side of the bird linked to the head facing the intruder, the "A" indicated a toner with a very close neighbor in this way, and usually did it from the same spot, behind the tallest clump of grass on the main "island" (6") in his territory. The neighbor would crowd at the same time on occasion. There also seemed to be a more subtle display, involving the fluffing of back feathers, but I saw it very few times, and may be too influenced by Henniker's paper. I saw one instance of a flying cWR supplant, when at the last moment the attacker turned flight forward the attacker and stretched them out, like a flying Black-tailed Godwit. Three birds were incredibly tame, allowing me to approach within 15' before ceasing to feed. They over looked still, they would not let me within 10 ft of one. Grid I (Farmhouse Puddle) Estancia Medeland Provincia de B.A., Argentina 24 December a minimum of 3 territorial cWR on grid this morning, possibly more. I have not been watching them as carefully as previously, however. One flock appears