JPM Myers 1974 Journal Linear grid, Arroyo Llano, Estancia Medaland, 35 Km S. of Trenelos by road, Pto de Madariaga, Provincia de Buenos Aires, Argentina 8 November (cont'd) combination with the fact of the damming effect which appears in the arroyo at low water levels, there are areas exposed to WR which are probably of a better quality than the usual mud along the water. That is, flat expanses of silt, freely exposed by the falling water, become available. Grid totals: Calidris fuscicollis 13; C. bairdi 5; C. melanotos 1; Limosa haemastica 2; Tringa flavipes 3; Tringa melanoleuca 1; Himantopus h. 7; Vanellus chilensis 1; Charadrius fallax 2; Pluvialis dominica 3; Anas georgica 2. Running total linear grid totals: C. fuscicollis 72; C. bairdi 6; C. melanotos 1; Limosa haemastica 5; Tringa flavipes 8; Tringa melanoleuca 1; Vanellus chilensis 3; Pluvialis dominica 12; Ch. fallax 7; [Ch. semipalmatus 1]; Himantopus h. 19; Charadrius forquatus 4; Anas georgica 5; Anas flavirostris 4; Larus maraculipennis 3. After completing this latter sample, we continued down the Arroyo to the place at (7,13) surveying flocks for band-tailed birds. Then, we turned around, and began repairing the linear grid, whose status have been depleted by horncrass and crows. After completing this, we put in a buffle grid at (13,21) for 90 min. bird calculation, and also surveyed the local (buffle and golden flocks). During the morning and afternoon we also took microhabitat data for Tryngites, fuscicollis, fallax, melanotos, Tringa f. and Pluvialis. Finally at 1415 we returned to camp. Throughout the day cloud cover never rose above 10%, the wind was light to moderate, continuous out of the east. Temperatures rose to ~23°C but by late afternoon (1800) had dropped to 16°C. (13,21) Estancia Medaland, Pto de Madariaga, Provincia de Bs Aires Argentina quasi- tempo 6° at 0500 0525 arrived at grid 19, which we had placed yesterday afternoon in order to facilitate a calculation of % territorial Tryngites. The whole grid measures 100 x 100 m and is divided into 16 25 x 25 m subunits with strategically placed stakes at other points in order to allow more precise position determination. The grid lies in a uniform (to the eye) expanse of typical short-grass buffle habitat where in the past we have invariably found Tryngites (Phaegaeus). I directed my attention to a 75m x 75m portion of the grid, choosing an area with a maximal number of Tryngites present. During the first hour 9 November