SP Myers 1974 Journal Arroyo Chico, Estancia Medland, 35 km S. of Trencho by road, Ptdo de Madanaga, Pcia de Buenos Aires, Argentina 22 March (Cont'd) the requisite gate. We followed the Arroyo to a point at which fording in car was possible, and then continued back. However, on route, making a detour up out of the course of the stream, we briefly entered a field similar in vegetation structure to Tower Llanos. Short grass, perhaps thicker than that on the Llanos but not taller. It is bordered on one side by the banks of the stream (Chue, as elsewhere, 3'-9' elevated above the cord outside the Arroyo; the elevated area outwardly covered with thick (1'-1.5') spring vegetation including thistle, with occasional vizcacha holes within either the vizcacha or burrowing owls in residence [?]) and the other by what appears to be an old streamside elevation, suggesting that the stream has since changed course (the what would have been the channel is now filled in). To the South the field continues for several hundred meters, but appears to shift abruptly in that direction into a group of perhaps taller dimensions. In the field in one area nearer the Arroyo are a series of lower areas replat with Solanum. To the east beyond the first formation which I suggested was an old bank of the Arroyo, the field begins anew, continuing for ~150m. Then branch sedge picks up, and a third marsh carrion from free. It appeared to be extensive (and in fact, is partly) the marsh where I collected 24 February. Anyway, on this field we found the usual Lessonia and [illegible], although less dense than on Tower Llanos, Vanellus (several groups totaling over 20) and flocks of Thresorcorus ruminicivorus, of which I collected 2 (118,119). Uncounted 60 Thresorcorus, but these are certainly more. I was struck by the fact that the commoner birds of Tower Llanos now, Lessonia and Anthus are nevertheless obvious here, and that the grass is so much thicker (i.e., horizontal density greater) whereas height of the vegetation is not that different. This field is in Petreto 18, beginning just beyond the fence separating it from 19 Grande. Leaving here we drove to the above-mentioned fording point, 75m E of Pte 11 bridge, and returned down the Arroyo, combing WR + searching for banded birds. By this time it was past 1000. We found 2 bands along the linear grid, Pyg Lyra and Pyg Lyra, even though the former was in the same position where I found it 20 March. Pyg Lyra was in the vicinity of the territory. There was a total of 94 WR alongside the entire stretch between the bridge and the fence dividing Petreto's 19 chico and 200 23. See (WR supp and Thresorcorus suppdent). 23 March dawn windless, temp ~16°. A low dense line of clouds was on the N/E horizon, extending perhaps 5° W above the horizon. This has been a typical dawn cloud formation for several weeks now.