Vaux Swifts in Late Summer in South Pasadena, California
Vaux Swifts in Late Summer in South Pasadena, California.-On July 31, 1943, the writer together with several other observers saw at least four swifts, apparently Vaux (Chaetzlra vazuci), flying low over the trees and houses overlooking the Arroyo Seco in South Pasadena, Los Angeles County, California. The time was just at dusk and the birds chattered noisily, often chasing one another or sailing close together with wings at a sharp dihedral angle. On August 2 I found their roosting place, a two and a half story chimney, the flues of which were of fire-type terra cotta pipe. On each of several visits in the next two weeks all four swifts were seen flying noisily about over the area for 3 to 10 minutes before settling into the chimney at about one-half hour after sunset. None was ever seen on any mid-day visits.
At least two of the birds seen in early August had one or more remiges missing from each wing, but they gradually regained the complete wing outline by mid-September. Several worn flight feathers and one spine-tipped rectrix were retrieved from the hearth below the roost on August 9; these later were compared with specimens of C. vau& and C. pelagica by Mr. George Willett of the Los Angeles Museum and found to be the former, as was to be expected. A thorough examination of the roost chimney with hashlight and mirror on August 10 revealed a considerable number of droppings but no evidence of a nest, the possibility of which had been considered since the birds were present several days in advance of the previous earliest fall date listed for southern California (see Willett, Pac. Coast Avif. No. 21, 1933:95).
The swifts’ calls, at first a vigurous and very rapidly repeated ckipper-chipprr-chipper (almost a trill), became less frequent and were not heard after September 3. On this date also, only three birds were seen and on subsequent visits on September 10 and 22 only two were noted; these always dropped into the chimney almost simultaneously, as did two (the same two ?) of the four present during August. All were gone by October 3.
Because these swifts were present so regularly at the same roost and because their behavior was so markedly different from that of other Vaux Swifts seen in southern California, the writer believes they were not merely migrants. Needless to say a careful watch will be kept in 1944 for any reoccurrence.-HOWARD L. COGSWELL, Pasadena, California, November 24, 1943.
