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22? THE CONDOR Vol. XVI Plegadis guarauna. White-faced Glossy Ibis. During our stay large flocks of White-faced Glossy Ibis were seen both feeding and in flight. The numbers appeared to be greater toward the end of our visit. Several of the flocks in which the individuals were counted numbered thirty to forty. From their actions we inferred that they had not yet begun nesting. Shore-birds.--Black-necked Stilts (Himantopus mexicanus) were by far the most numerous of all the breeding birds in the vicinity. They nested very commonly on muddy islands in the larger ponds; but nests were also found. along the margins of ponds out in the brush as well as in flooded fields. In such places as last indicated the nests had often been built up so as to reach above the surface of the water. It was suggested to me some time ago by lVIr. Paul J. Fair that Stilts alone among all the water birds, seem to have sufficient intelligence to increase the height of the nest in order to keep it from being flooded by rising water. l?Ir. John G. Tyler attests to the same thing. Evi- dence which we obtained certainly points in this direction. On the banks of ponds and on muddy islands the nests were nsually very simple in structure, being a hollow in the ground lined with a few weed stems. Many nests found above water may well have been of this crude structure before the encroach- ment of the water. When seen by us, however, they were well constructed nests built up to a height of six to ten inches (see figs. 64, 65). It seems quite possible that extra layers of stems could be added to the nest as it and the eggs were threatened with flooding by the rise of the water. Two nests in which the young were just hatching were noted May 21, but all the rest of the nests contained three or four eggs. Fresh eggs were examined on ?Iay 22. Avocets (Recurvirostra americana) were still more partial to the muddy islands than were. the Stilts. The former were present in moderate numbers, and a nest containing three eggs was found on ?Iay 23. A downy young one several days old was noted on May 21 swim- ming in a shallow pond and turntug tail up as it tried to reach something on the bottom. Its stomach was found to contain eight or more small water beetles (Dytiscidae), i Jerusalem cricket (Ste?opelmatus), 1 larva of a dragon-fly, I small bug (Pentatomidae), and I centipede (Scolopen- dra). Along the muddy shores of ponds five Snowy Plover (AEgialitis nivosa) were seen at different times. Three were noted on lVIay 17. Their light brown backs so harmonize with the color of the muddy shores of ponds that it is im- possible to see the birds until they move. The stomach of one contained more than ten water beetles (Dytiscidae). These birds were very tame and a photo- graph was taken at a distance of eighteen feet. A flock of twenty-six Western Sandpipers (Ereunetes mauri) was noted on lVIay 17 and two Northern Phalaropes (Lobipes lobatus) on lVIay 19. Killdeer (Oxyechus vociferus) nested most commonly on the alkali flats away from the water. When one walked across such stretches as many as ten of these birds could be seen running along ahead or standing "teetering" and incessantly repeating their call. The eggs in one nest found lVIay 15 had been broken on the under side, just as if the weight of the bird, pressing the eggs against the small pebbles forming the floor of the nest, had crushed in the shell. Another nest found on ?Iay 15 was unique in the facts that it was placed on a small grassy knoll surrounded by water, and that the cavity was well lined with short stems of devil grass. A downy young one was found l?[ay 22.