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 THE. CO.I'IB?R Volume XIX Janxar-Febrar, 191 Number I FURTHER NOTES ON THE WHITE-THROATED SWIFTS OF SLOVER MOUNTAIN By WILSON C. HANNA WITH FOUR PHOTOS HE MAY-JUNE CONDOR for 1909 tells of my early experiences with the White-throated Swift (Aronautes melanoleucus) on Slover Mountain which is located in the San Bernardino Valley near Colton. Continuous observations since that time have brought forth a few more interesting points, particularly concerning the nests. During the breeding season single birds, or birds in pairs, are often no- ticed in flight. The nesting sites are then to be found by watching where these birds go. When a likely crevice is found, observations must be conducted to decide whether the nest is under construction, with eggs, or contains young. With the exception of set no. I and set no. 4, all nests that I have observed have been situated in crevices with bends and so far away that nothing could be seen even as to the location of the nests; and these two sets are the only ones I have taken where injury to some of the eggs in the set has not resulted. The nesting cracks are best located by watching the birds carry feathers into them, but as the nest-building and egg-.laying period may require over a nonth there is much chance of destroying the unfinished nests or in waiting too long before removal of the rocks. On several occasions I have been greeted by the screeches of half-grown young in crevices where I had expected to start operations for collecting eggs. Locating the nesting cavity and estimating the proper time for collecting the eggs is but a mere start in the righi direction, for the cavity is usually at some almost inaccessible point on the cliffs, 20 to 150 feet from the bottom, with nany dangerous, loose, overhanging rocks. There is no certainty as to the