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 MAY., I902. THE CONDOR 57 about overhead continually, ever ready to pounce down on some unprotected cormorant's nest. We observed one Baird cormorant that was scared from its nest. No sooner had she gone than two gulls pounced down upon the va- cated eggs, and while one of the rob- bers pierced two and devoured the con- tents, the other gull picked up the re- maining egg in its bill and flew off to the adjacent rock. There were a few pigeon guillemots (Cepphus colmba) about the rocks, but not very many were found breeding there. We noticed a number of pairs of black oyster-catchers about the rocks, but were only able to locate one nest. The birds were flying back and forth continually uttering their whistling call. The nest of this species that was found was on the south side of the rock, on a little slope where the fine pieces of rock had fallen down from above. The three eggs were placed without the least sign of a nest, two of them were near together while the other was about eight or ten inches be- low. All of the eggs were pipped and just about ready to hatch in the warm sun. The parent birds were flying about the rock but did not come near the eggs. 13erkele. y, Ual. Nesting of the Prairie Falcon, BY O. W. HOYVARI), IOS ANGELES, CAL. ARLY during the spring of last .year while doing some develop- ment work on one of my min- ing claims in the Huachuca Moun- tains in Cochise Co., Arizona, my atten- tion vas often attracted by the screaming of a pair of prairie falcons (Falco roem- ir'anus). The sounds seemed to come from a tall cliff near the crest of a high rdge on the opposite side of the canyon in which we were working, and al- though the distance was too great to watch the birds I felt certain they were nesting on the cliff. When the birds had been in the vicinity for several weeks I felt sure it was time for a full set (,f eggs, so my partner and I made a trip up to the cliff to look for the nest. When we were within a few hundred feet of the cliff we were greeted by a sndden screaming, and on looking up saw three prairie falcons in an aerial combat. Their flight ws very swift and grace- ful; undoubtedly two of the birds were the pair nesting in the cliff and the other an intruder. One bird of the pair was following in close pursuit of the enemy while its mate would ascend high into the air and with folded wings drop like a falling stone and at the same time utter a shrill scream. Just at the second one would naturally expect to see the enemy dashed to pieces, a' slight turn of the tail would carry him to one side and the would-be assassin would dart harm- lessly by like a flash. We watched the performance until the birds had passed out of sight. The rest of the way to the cliff was a hard climb through the thick oak brush and over large, jagged rocks. When we reached the cliff two of the falcons had returned and were flying about in their usual manner with quick fluttering wings, occasionally uttering their pecu- liar scream. When we had watched the birds a few minutes one of them, presumably the female, fle; to a cavity about half way up the face of the cliff and disappeared. This I felt sure was the nest, as the male bird lit on a sharp projection of the cliff not far off. I had firty or fifty feet of small rope with me but not enough to do any good so I de- cided to let the matter rest until I could obtain a longer and thicker rope. Before leaving the chff, however, we looked around to see what else we could find; there were several turkey vultures sailitg back and forth, also a golden eagle was seen and a pair of