JPMyers 1974 Journal 42 Arroyo Chico, Estancia Medelard, 35 Km S. of Ivancho by road, Pteb de Mladaniaga, Provincia de Bs. As., Argentina a foot or so wide and 25" deep E in some places. At several places along the grid, in subunit 1 (at the curve), subunit 4, and subunit 9-10, there appears to be a slightly raised portion of the arroyo, effectively serving as a dam, so that in these spots the channel is very narrow, and between them there are long + somewhat wider reservoirs. Grid totals: White-rump 1,6 (17); Hudsonian godwit 1,1 (2); Charadrius falcklandicus 7,8 (17); Boniby 3,2 (5); Black-necked Stilt 4,13 (27); R.B. Magpie 1,1 (2). Running down totals: 0830 (White-rump 16,74 (90)); Godwit 4,4 (8); G Yago 0,4 (4); S. Gouring 0,5 (5); Ch. falcklandicus 13,30 (43); Bonibyx modestus 4,7 (11); Black-necked Stilt 29,42 (66); Neotropic cormorant 1,3 (4); S. Screamer 0,2 (2); Maguari Stork 0,8 (8); Speckled teal 0,3 (3); YB Pintail 0,3 (2); B. hooded gull 3,4 (6); Cindodio fuscus 0,1 (1); Covadonga Pipit 0,1 (1). After completing these counts I moved out over the llanos (finding NO buffle) and back up to the Potrero above the N end of the linear grid. A large flock of WR was foraging just beyond the fences, 90 individuals, very tight although with some movement, feeding along a 75m stretch of arroyo. This is the largest feeding assemblage I have found to date in the arroyo. They proved to be quite skittish; my movements spooked them, splitting the flock up somewhat. (I followed them upstream, + after a brief period of observation (see WR spacient) I collected 3 WR (131,132,133) and one Bonibyx (134). When I returned toward camp the weather was as threatening as it had been all morning - in fact a series of long linear clouds had passed over us from the E-W, moving almost in direct opposition to another, lower layer of equally threatening clouds. A few streaks of rain fell. 16 April 0600 went out to Arroyo with Arturo Tarac for netting between subunits 8 and 7. Temp at 0600 = 13°. No wind, slight mist with a 10% cloud cover along the ENE horizon - We were late getting out, and got only 2 nets up before light flocks began to rise at 0720. First WR 0725 approximately. Netted 5 WR, 2 Ch. falcklandian, plus one previously netted WR (RoLoy). The weights on the WR were amazing, one surpassing 600g!! The Arroyo level in this part is very low - in fact almost no current exists. The deepest part of the channel is less than 3" deep. Otherwise: