SPU11/5 1979 Journal 41 Arroyo Chico, Estancia Medland, 35 Km S. of Trencho by road, Ptd. de Madariaga, Pcia. de Bs. Aires, Argentina followed closely by a Peregrine Falcon, flying north, low over the Arroyo (26' high). It passed almost directly overhead + was unmistakable. Although the Zonibyx and 2 Ch. falke returned before I left at 1100, only 3 WR approached the area, walking slowly while feeding up from subunit 10. Tower Llanos, Estancia Medland, Ptd. de Madariaga, Pcia. de Bs. Aires Returning from the linear grid to camp I made a complete circuit of Tower Llanos, looking for upland species. Found 100+ Thinocorus, especially near the Thrift pole, 2 Zonibyx (both solitary), and 3 Orcopahus by the N fence, and 2 Tryngita, near the tower. Arroyo Chico, Estancia Medland, Ptd. de Madariaga, Pcia. de Bs. Aires, Argentina At dusk we went to the Arroyo to try a new trapping technique: I built a butterfly-type net with a 10' dam pole to snare spot-lighted birds. From previous mornings with the car headlamp I thought that such a net would be productive. By 1900 the sun was behind a heavy bank of SW clouds, and a stormy S wind was bringing a thick fog across from the S, racing over the pumps. The rapidity with which the sky changed from a friendly puffy-com- tus to the low threatening + immensely dark cover was impressive. No noticeable temp drop; in fact it was quite warm. I was amazed at the arroyo to find that at several spots, particularly by the curve, there was no current. Indeed, several small sand spits ran completely across. Perhaps it is the S wind, opposing the current, pushing the T.D. back up, and doubt that it would have dried that much today - WR & Ch. fell, Varela, Airmontepes, and Zonibyx were all roosting in the arroyo, with concentration at the curve below the tower and between 8+4 of the linear grid. See WR sp. accent, I was unable to catch anything. Sun hit horizon at 1925; we returned to camp 2130. One Vizcacha & Nycticerax hunting along linear grid. Many eared out at night. Again. 15 April out in Arroyo 0900 spot-lighting cars unsuccessfully (see sp. accent), largely because there were so few. I found only one definitely roosting. Many Ch. falke landicus. Temp 0630: 16° 100% clouds (no fog), light N wind. 0805 began reading linear grid. The Arroyo, in contrast to the evening of 13 April is now flowing again, even if its only