JPMycro 1974 Calidris fuscicollis Grid 12, Arroyo Chico, Estancia Medeland, 35 km S. of Swancko by road, Pato de Uldaraga, Pavin de Buenos Aires, Argentina 22 February (cont'd) when other birds approached within 2 m while in his activity center. Sometimes, twitter- ing began as far as 3, 4, or 5 meters away. The distance depends upon whom he addressed - what they are doing. For example, other birds in the immediate vicinity are calling, and if two birds engaged in such a fashion approach Ryllyg, it almost invariably begins to flutter at a distance of 3-4 m. Ryllyg showed a few short instances of crouching, but nothing expensive. No tail raising. B receptacle - Although Ryllyg was not territorial, its activity had no fixed reference points, + the probability of attack appeared to depend principally upon the position with respect to those points. But attack appeared to be more dependent upon distance from Ryllyg. 10:35 we began following 2/22 B. After 45 min it flew with all (but 2) other birds on the grid upstream. In the observation area however 2/22 B appeared to be much more classically territorial than Ryllyg, defending an area of ~100 m² in a diagonal from (5,2) stake on the outside to (8,0). Supplemental flights involving flights of at least 20 m were seen. 2 definite foraging bouts, one by (5,1) + one ~10 m from (8,0) stake, the (5,1) was most criticized, with 2/22 B frequently flying to supplant. Crouching seen here. Intruders into the territory were regularly supplanted from any distance. When the flock flew at 11:20, we also could not discern any disturbance, yet the birds acted as if there was jet calling upon take-off, which was sudden + simultaneous, the flock flew downstream at least 150 m + landed. By 11:28 Ryllyg (which had been foraging just south of the grid) reappeared about 150 m W of the grid. The flock had been walking NNE south. Ryllyg also back to almost on grid. 11:30 Ryllyg in (3,2). 11:33 it appears that 2/22 B is back, re-supplanting again in same location where two before flight. 17:40 - We have left the grid and are at the territory of Ryllyg near Grid 4. It is not here, but instead 100 m upstream! (3300 N) 12:15 Ryllyg is back on territory. We returned to the Arroyo at 20:45. Ryllyg was on territory. Took 4 grid counts on Grid 12 from 21:00 to 21:15, as the crew left for the evening. At 21:00 their dispersion was strikingly different from anything else we had measured earlier during the day - 7 WR in one 5x5 unit! Though they were certainly more scattered than at other times, they still managed to