JPMyers 1974 White rump Sandpiper 15 January Kim W of Farmhouse on Farmhouse Rd, Estancia Miedland, 35 Km S. of Juancho by road, Ptdo de Madariaga, Provincia de Buenos Aires, Argentina Both of us had been struck by the clumped way the birds herd, the fact that they were near A, instead of most being farther W, spread out. Now that pattern is AGAINST. Recall Q - a bird went into Q's old area just after A began defending again. Then perhaps A is not the only bird to have a fairly stable territory, provided that A=A'; Q=Q'. I shot A (070; a juv 0?) at 1645 [illegible] [illegible] - 1651 - no new shooting of A (The flock did not leave!) There have been at least 5 flights! Number of birds have moved into A's area, + are squabbling. Particularly a troika. Still very confusing. Within the 15 mx 3 m area A defended are now 8 birds - 3 but are being very aggressive, perhaps 4. A new flock (~10 again) came into the area from the E - they are the ones that have moved into A's old area. (The flock may have walked in from E (I was fixing A for storage) & thus did not see them arrive.) Less than 10 min after removing A there are violent fights over whole area! It's now chaos because of the surrounding birds. If a bird intrudes (or approaches) the "owner" does not necessarily chase right away, but does frequently. It looks as if it may be a relative position question. But perhaps not. Confusing because the action of one opponent forces the attacked bird toward another, & the aggression continues. The probability of attack appears to depend upon the direction that the attacking bird is facing. However, around 1704 - 5/7 birds within area are thinning out - 2 of them staying consistently (each of us are following one) within area. Is it being structured? What happens once we have spent more time in the area? When the birds are feeding, they often continue feeding despite the close presence for approach of other birds - but then they "clean house" - clearing all the other birds away from their vicinity. This is what we are seeing now, with many birds within a small, defined area. This contradicts with A -> an intruder was expelled when it encroached, not dependent upon the activity of the supplanting bird. It may have to do with the amount of time available. To be used for any version [illegible] Two after 20: I have seen a case of mounting - but only out of the corner of my eye so that the status of co-engaged birds was unknown. Followed by a crouch - birds expand + crouch. It may be an