JP Myers 1973 Journal Grid 9 (Farmhouse Puddle) Estancia Wedel land, 35 Km S of Juancho by road, Pucia de Buenos Aires, Argentina. 17 December cont’d Southern lapwings are raising 3 chicks (less than 1 week old). The lapwings are very aggressive particularly Cpler but including WR+Pectoral towards other shorebirds, and devote considerable time to chasing invaders away. The defended area includes at least part of the (0,0) area part of the grid; thus the lapwing behavior is having a pronounced effect on shorebird dispersion in that region. I did have some difficulty in running samples, for two reasons: the size of the grid units is large, and it is difficult to cover a unit well. I am observing from a point at which the scope is so powerful as to be awkward, but where it is still too far to use binoculars. Secondly, the habitat contains some microtopographic relief, enough so that a Pectoral can almost, if not completely, disappear. Also, bedraggling obscures a few areas of the grid (not completely). At 17:55 there was a large disturbance which caused many of the foraging shorebirds to fly, with alarm calls. I was not sure of the source of the disturbance, but there it may have been one of the ranch hands running a herd of horses into the Farmhouse area. However, he was several hundred meters away. Because of the alarm calls and the reshuffling, I took an additional sample at 17:55. Most of the birds had congregated in the (1-2,0) One idea which occurred to me while watching the regrouping following the disturbance had to do with the effect that feeding style may have on tightness of flocking. Birds that forage with their heads down may derive considerable advantage from flocking in tight groups, e.g. Microspalama. With my data on dispersion, plus additional material quantifying the % a bird spends with his head down or up, I should be able to examine this. Additionally, I predict that, if flocking is of anti-predatory significance (not necessarily in the selfish herd tradition), then territorial pectorals, for e.g., should spend more time looking up, i.e., less time foraging, than flocking pectorals. This is, of course, problematic — unless golden, but the intra-specific comparison may prove fruitful. I must take foraging behavior data in such a fashion that time available for observation is included in the measurement]. At ~ 18:45 major flocks of shorebirds left the grid. The first was mixed of WR + Lylap; they flew up from the (0,-1) and (0,1-2,0) area, landed in a flock near (2, 2-3), and then took off again towards the NNW when a 3 F4L flew over. Pectorals remained in the (3-4,0) area, but flew less than 5 minutes later. Golden’s remained