J P Myers 1979 JOURNAL 80 Arroyo Chico, Estancia Medeland, 35 Km S of Juancho by road, Pto de Madariaga, Pcia de Bs Aires, Argentina 25 April cont'd Jener NW to the Arroyo, and back. The Tajamar was full of shorebirds - 150+ WR (many territorial see spp accent; one banded R. lag); 50+ Hgduit, many black-mud Stilts, Ch. falklandicus and Zonibyx. Weather during the outing was blustery, with a mod ESE wind, 50-75% cloud cover, alternately threatening rain + then clearing, and temperature hovering around 13°C. 26 April 0830 5°C. At 0920 I entered the Arroyo with sky 90% clear, 10 wind. The lack of wind, as we had yesterday, has allowed the #10 to back down, so that the area below the course S of the turner has 1-3' of newly exposed mud and wet sand. The curve itself is essentially dry. Also dry was the entire area between the N end of 6 and about 45 m S of unit B. By a very fortunate coincidence I found two of the birds which had been territorial in the old B-7 stretch now on sub 6, + again territorial: They are Zonibyx RO and Ch.falklandicus Ryleo. Schunt 5 is not dry, but Ryleo was with a flock between 3 and 4. (See WR, Zonibyx, Ch.falklandicus, Hgduit sp accent). Several things appear to be happening in conjunction with the drying of the Arroyo, apart from the fact that WR's are just about to emigrate: 1) space is being reduced, and concurrently territorial birds are being forced to abandon if their stretch happens to dry (e.g. Zonibyx RO); 2) there are more birds present anyway, because surrounding areas have dried further; 3) new additional food is being exposed at the center of the Arroyo - the we are using a new feeding style - deep-picking instead of scratch peck. Tower Clance, Estancia Medeland, Pto de Madariaga, Pcia de Bs Aires, Argentina 1400 p.m. Tower Clance. Moderate E wind, clouds = 60%. Watching a flock of Orcopholus and Zonibyx forage near the S gate I took feeding data and microtopographic data from Orcopholus Within a quarter of a circle (90° arc) with a radius of 100 m were 9 Orcopholus, 5 Zonibyx, 17 Thincorius, 12 Lessonia rufa, 2 Cinclodes fuscus, 3 Geothrix curvilineata, and 2 Anthus coracium. The shorebirds were limited to this area, whereas the passerines appeared to continue on fairly evenly, the perhaps not the Lessonia. After taking the Orcopholus data I went on to the thistle patch / blance interface where the first Thincorius appeared, + when they have been ever since, + took one set of micro-data from a 8Thincorius. After this, and after satisfying myself that there were no huffies on the blance, I went to the Arroyo.