RUFOUS-WINGED SPARROW 909 



larger number of those of the Black-throated Sparrow * * * besides 

 a number of nests containing young." 



Courtship. — Twice I have seen billing or possibly courtship feeding. 

 On Mar. 12, 1952, in the Coyote Mountains (eastern edge of Papago 

 Indian Reservation, southwest of Tucson), I saw a pair billing, but 

 could not see whether any food was actually passed; collecting the 

 birds, I found them to be male and female with gonads sHghtly enlarged: 

 testes averaged 2.4X1.8 miUimeters, the largest ovum was about 

 0.6 millimeter in diameter. The other occasion was on Mar. 29, 1958, 

 in the swale habitat near Tucson. After one of the two pairs in 

 nearby chollas had flown, the remaining pair then billed several times; 

 the upper bird reached down and sUghtly to its left, whUe the lower 

 one seemed to reach up, to the right, and a bit forward. I feel sure 

 that they were only biUing, for I saw nothing in their bills and no 

 swallowing actions, nor had they apparently been feeding just before. 

 Neither this one pair nor the other in the chollas was collected. 



Nesting season. — Customarily we confine our main discussion of 

 nesting to the location and construction of nests, relegating the dates 

 to a few lines at the very end, after the migration dates and casual 

 records. To do so with the rufous-winged sparrow, however, would 

 be to pass over one of the most fascinating aspects of its life history, 

 which sets it (and most of the other Aimophila sparrows) off from 

 the general run of birds of northern latitudes. 



The nesting season corresponds in all cases with a season of rainfall 

 and warm to hot temperatures. In normal years, though the testes 

 of males enlarge greatly in late April or May, no eggs are laid near 

 Tucson until the end of June or early July, and perhaps later in years 

 and areas of delayed rains. Gale Monson and I found nests with 

 one and four eggs (incubation of the latter just starting) on June 30, 

 1940. 



On June 29, 1954, 4K days after the big rains began, Joe T. Marshall, 

 Jr. (MS.) found two nests in the same state of construction in swale 

 habitat. "Herbaceous vegetation is now very definitely sprouting — 

 tiny cotyledons are up everywhere, and green is starting to appear 

 on the perennials." One of these nests seemed ready for eggs on 

 July 2, but was unlined. Similarly, Herbert Brandt (1951) never 

 found nests in his years in Arizona, for he usually left about the end of 

 June. 



Thus it came as a tremendous surprise when Eliot F. Porter dis- 

 covered rufous-winged sparrows with large young on the wing on 

 May 19, 1952. This occurred in a swalelike habitat 6^ kilometers 

 north of Vail, after heavy March and April rains. He also found 

 apparently full-grown young in a weedy desert wash on May 24, 1952, 

 more than a month before the first eggs are usually laid. 



On May 20, 1952, E. F. Porter and I took a census of % kilometer 

 (J^ mile) of a broad swale. We found three or four families of young 



