The walls of a deserted Quechua hut had been appropriated by a flock of bay-winged cowbirds (_Molothrus badius_) for their nesting-sites. Dozens of small, round holes penetrated the thick, earthen walls, and some of them extended entirely through; the latter were not occupied. Apparently whatever birds had drilled the cavities, frequently surprised themselves by emerging suddenly into the daylight they were trying to get away from, at the far end of the burrow. However, not to be discouraged, repeated other attempts were made, some of which were successful as the walls varied in thickness. A small, flat nest of sticks lined with a few feathers comprised the bay-wing’s domicile. Some of them contained young birds, and one had five eggs in it. The adult birds always remained in a flock in the vicinity and kept up a shrill screaming while we were near. Large, blackish rails inhabited the reedy marshes; they came in flocks to feed in the velvety green islands interspersed among the weed and water covered areas. Watching from a concealed position, we could see them strut unconcernedly about, flicking their tails over their backs and jerking their necks and picking up the tiny mollusks and insects that were so abundant. When alarmed they craned their necks, looked about inquisitively, then gave a few hoarse cackles and ran into the weeds; within a few moments they returned, one at a time, and at first slowly and cautiously; but soon, forgetting that danger might lurk near by, they rushed for the spots where food was most abundant. Rails are peculiar and interesting birds. The body is narrow and compressed like a flea’s; this enables them to slip through the dense reeds and water-plants in which they live. The comparatively long bills make it possible for them to pick up food in shallow water. Their long, slender toes, giving the feet a wide spread, make walking on floating vegetation and soft mud easy; nevertheless, at least some species are good swimmers. Flocks of night-herons spent the days in a small clump of willows fringing the marsh. At dusk they grew very active and we could hear them croaking from afar. They are splendid eating.