JPM Myers 1974 Journal 25 April (cont'd) Arroyo Chico, Estancia Medland, 35 Km S. of Joaquin by road, Pto de Madariaga, Provincia de Bs. Aires, Argentina fairly evenly dispersed along the shore (one every 50-95 m) for the first 3-4 Km. Up to this point the substrate is a sand with many old shell eveduct (and the banks show definite layering with one 8" thick deposit of shells about 3' from the surface). This substrate develops than the mudcler one which characterize much but not all of the Arroyo along the Rio Cargnoid. However, after 3-4 Km, during which the water grows wider & deeper, reaching a max width of 15 m and depth exceeding my boots (1.5') considerably; as the banks become steeper, the sand/silt layer disappears, and the Arroyo edges become overgrown with thick, high (1.5') grasses - this continues beyond the point where I stopped. At this point, where a major (in comparison with the Medland bridge) bridge crosses, it is obvious that there has been a lot of human effort put into defining the channel, springing up the banks, & straightening it out. In the vegetation were at least two Willows, Bonotrichia, and Plumbeous rails. Along the crest of the banks, apparently cropped short by ubiquitous sheep, I saw one small (8-13 birds) flock of Ornopelus. No other shorebirds along this entire stretch. The design for the Arroyo for a moment do comment upon one prevailing feature of the pampas in their area (in fact all of the pampas that I have seen from Belia Blanca to Santa Fe) - the horizon is invariably broken up by monocles - clumps of trees ranging in size from a few trees to several hundred, especially (except right near the coast, particularly to the north east of Madariaga and past Castelli) imported trees - Eucalyptus, poplar, oak - planted around buildings but sometimes, as near La Urquiza (see map) out in the middle of fields by no buildings whatsoever. I think that the dispersion pattern of the monocles - considerably patchy and of limited area in comparison to the vast grasslands which surround them, are of more potential ecological importance than as shelters for man or a relief from the visual experience of an unlimited, flat horizon. I propose that they may in time serve as 'islands' offering relative safety for nesting in comparison to the ground in the grass. The islands are also offer a very special dispersion pattern to those spp. using the woodland habitat which they comprise. With respect to social systems + for nesting dispersal, I suspect that the patchy monocles may eventually lead to refuging exploitation by spp. which have been able to conquer the breeding territory - that is to the pt. where a colony develops within the mont. Anyway... from the bridge I followed the body of water - a baja mar (water-holding pond) around to the W, and then going to the end, and then followed the nearby