JPMyers 1973 Journal Grid 1 (Farmhouse puddle) Estancia (Meckland), 35 km S of Junin by road, Pucara Buenos Aires, Argentina 24 December cont'd specific attacks and supplantation. Indeed, I am enough WR - Piedoral pairs to suggest that the association may not be accidental. It will be interesting to determine if the white rump and Piedoral territories are placed independently of one another - but greatly impossible to then separate out possible habitat influence on the placement of activity + territory centers. the 2 Ylegs present on the grid this morning was also territorial, excluding all other 2Ylegs from foraging. Although I picked up a BNStilt pair in one cant, they were frigidly. One of them exclude other BNs from the entire pal (all 130 m long of it). The only shorebird species which at no time showed territorial behaviour were Micropalama (Crapaccant). Minimum of 5 territorial Piedorals, 3 territorial WR and 1 territorial Ylego on grid this morning. Probably more WR than 3. 0845 - one instance of what must be called a default grouping -> 2 Red's and 2 WR in the (5,6) unit [wcu] (the grid to extend that far), still of them, three times they were chased out of other areas. The territories of Piedorals + WR must be strongly affected by Lapwing activity - not only in the fact that in some areas the Lapwings will not allow other shorebirds (e.g., when their chicks are) - but also in and the constant stirring effect that their chasing must have on the dispersion of adjacent birds - but also because the exclusive area of the Lapwings change in time. This morning, we have snaked (Crapaccant). The defended area has shifted toward the center of the grid, incorporating more or more units. The instability! Add this to the longer term changes in habitat-induced by elyting! Grid totals (22!) Samples; Polition Species, area (range) total): Piedoral 6.6 (3-13) 146; White rump 6.9 (4-17) 159; Micropalama 0.1 (0-2) 2; Galliariago 0.2 (0-2) 4; 2Ylego 0.5 (0-1) 11; G.plover 0.3 (0-1) 6; BNStilt 0.1 (0-2) 2; Slapwing 0.4 (0-3) 8-inc 4 records of chicks; Agelaius thalassus - (0-1) 1. 26 December: Out on observation post, fly at 0510. Clouds 80%, temp 19°C, a light N wind. Southern Lapwing active in clearing shorebirds from c. (4,0), (4,1) etc from the beginning, although Lapwings not consistently active throughout the morning. It was immediately