l?ov., 1914 BREEDING O1? THE BRONZED COWBIRD IN ARIZO NA 257 male are seen with them. They are quite tame and get in the shade of a shed and eat watermelon every day. When the Bullock Oriole began breeding I went tb work to examine all the nests I could find. I looked into twenty-eight but no alien eggs were found. Then the Hooded Orioles began nesting, and while they seem fairly numerous, comparatively few nests are seen and most of them hard to reach. June 28 I climbed to a nest of the Hooded Oriole about twenty feet from the ground in a big cottonwood tree. The nest could not be reached, but get- ting directly above it I saw a greenish white egg, and knew the long looked for was found. I used a pocket knife vigorously, cut the big branch off and secured the nest. In it were two eggs .of the Bronzed Cowbird and four of the Dwarf Cowbird (Molothrus ater obscurus). The nest was typical of the spe- cies, and made of fiber from the Washington fan palm (see fig. 73). This was at Sacaton, on the south side of the Gila Eiver. Both eggs of the Bronzed Cowbird had holes picked in them, one showing a little incubation, while the other was nearly fresh. Of the Dwarf Cowbirds' eggs, three were slightly in- cubated, and the fourth fresh. What became of the oriole's eggs is a problem, as is also the cause of the holes in the Bronzed Cowbirds' eggs. My opinion is that the Dwarf Cowbird that deposited the iast egg saw the nest was too full of alien eggs, and so picked holes in those of the other species. If such be the case it would explain why the Bronzed Cowbird does not increase faster, for the Dwarf is very numerous here. As nearly as I can estimate the number of the former species they remain about the same as when I first saw them five years ago. If the oriole picked the holes she showed rank favoritism in saving the Dwarf eggs. Evidently her patience was exhausted, for the eggs were cold when found, and the nest apparently deserted. At Santan, July 7, I found a Hooded Oriole's nest with four of her own eggs and one of the Bronzed Cowbird. The nest was seventeen feet up in a cottonwood, and built of grass. Incubation was advanced, and one of the Oriole eggs was infertile. Another Hooded Oriole's nest found the same day had three Oriole eggs and one Dwarf Cowbird egg, so the Dwarfs evidently use the Hooded Oriole frequently as host, though I have never found them in Bullock Oriole nests. July 11, not far from the nest with the one Bronzed Cowbird egg, I found another nest of the Hooded Oriole with two legitimate eggs and two of the Bronzed Cowbird, incubation begun. This nest was in a cottonwood tree about fourteen feet from the ground. 'and built of grass with some horse hair lining (see fig. 74). Two other Hooded Orioles's nests exam- ined this season contained only the .owners' eggs. A few notes on the actions of these birds as observed here may prove of interest. With few exceptions'they show 'no indications 'of being paired, as do most birds. They are seen singly or in' twos or .threes of/either sex. One day there were four males eating watermelon in the back yard near the door, and two females were out in the barnyard by themselves. Two males have been together in the school grounds much of the time, and nearly always when females are seen they are by themselves. It is not strange that they seek soli- tude, as the males appear so amatory as to be a nuisance. The courtship antics are interesting. A male will approach to within three feet of his partner, fluff out his feathers, stand up straight and begin to flutter his wings. He increases the speed and violence of the fluttering till he appears in a perfect frenzy, then suddenly springs into the air from three to six feet and slowly descends, body perpendicular, beak thrust against breast and tail thrust forWard under the
