JPMYR3 1974 Zonibyx modestus 22 April cont'd Tower Lanes Estancia Medland, 35 km S of [illegible], Juancho by road, Rebelde Madariaga, Pcia de Bs Aires, Arg. Zonibyx are obviously moving into the upland habitat on the llanos. A flock is by the Nigate on the llanos, particularly in the very bumpy short-grass (Cynodon) lower area which has become wet water-filled during very rainy periods (i.e. it is lower than the surrounding llanos). A few definite territorial birds here. Also solitary upland Zonibyx near the Huinacu pahel + cut in the middle of the llanos. Several flocks of Huinacous have their one or two Zonibyx fly by and foraging up the Huinacous. A new flock of Zon on the S side of the Huinacu pahel - 9 birds in total. Zonibyx territorial flight appears similar to fallhavicus in that the spatial position + orientation between the birds is very stereotyped - parallel orientation and anti- parallel, with the 2 birds running a little bit, one changing direction, then the other... Bad feathers raised. Some violence - one instance of a Zon hitting another with its wing when the two birds oriented parallel, became very close (4"?) Arroyo Chico, Estancia Medland, Ptdo de Madariaga, Pcia de Bs Aires, Argentin an obvious dimorphism appears to exist in Zonibyx. Nothing found birds weighing 490g + elso 60-75. Three prepared were both 85 and of the smaller weight. While watching a barred! WR today, I think that I can discriminate between 2 sizes of Zonibyx, one about the size of fallhavicus + the other much bigger. Can it be that there are differences between P + Q Zon. interactions with WR or Ch.f? Zonibyx are very aggressive - going after both WR + Ch.f. They appear to force their species away from the water - sand interface: we aren't bothered if they are in the water; Ch.f. can avoid if they're up on the beach. I wish I had precise data for the period when there were only WR + Ch.f. present to compare with now. 23 April melted 2 Zonibyx this morning at subunit 1'; one died and 2 prepared it (135-g). Several territorial Zonibyx in this stretch of the Arroyo. Zonibyx does not, appears forage with another individual (sp. pair) - it is territorial period). 26 April The drying Arroyo has caused many birds to move, including the 2 Zonibyx banded 16 and 20 April: the latter, Ro, pursued on its territory on subunit 5 until there was only a small muddy paddock yesterday, less than 3m long and 1m wide. Today that is dry. But I found Ro down on