874 U.S. NATIONAL MUSEUM BULLETIN 23 7 part 2 



Although the long nesting season has led many ornithologists to 

 assume that the vesper sparrow is double-brooded ("probably even 

 three sometimes," Forbush, 1929), two recent investigators, working 

 with color-banded birds, have proved that the vesper sparrow is 

 indeed double-brooded, at least in southern Michigan. John L. 

 George (MS.) reports that "a banded pair that raised two broods 

 successfully hatched the second brood 29 days after the hatching of 

 the first." Francis C. Evans found one female that successfully 

 raised three broods in one season and states: "Of the remaining 28 

 records, 13 raised two broods and 15 raised only one brood. I cannot 

 definitely say of any pair that it failed to raise even a single brood, 

 and I believe that almost every pair succeeds in raising at least one 

 brood." 



On May 17, 1946 I observed copulation by a pair of vesper sparrows 

 on the ground in whose nest the first egg (cowbird) had hatched that 

 day; the male then flew to a tree some 50 yards away and the female 

 returned to the nest. That this species undoubtedly is double- 

 brooded in New York is suggested by E. H. Eaton's (1914) statement 

 that fresh eggs may be found "from the 28th of April to the 20th of 

 May," and that "later sets are frequently observed from the 20th of 

 June to the 25th of July." Theoretically there is time in the period 

 mentioned above for a pair of vesper sparrows to raise four broods 

 dm-ing a single season. In view of the frequent destruction of nests, 

 however, such a possibility is unlikely. Evans found 52 percent of 

 137 nests to be successful in fledging at least one young sparrow. 



Plumages. — G. M. Sutton (1935) made a careful study of the juvenal 

 plumage of the eastern vesper sparrow, which he describes as follows : 



The natal down of this species is grayish brown. With the molting of this 

 down a heavily streaked, strongly black-and-white nestling-stage of the juvenal 

 plumage appears. Individuals from eight to twelve or fifteen days old are in 

 this dark plumage-stage, which appears to be as nearly a complete juvenal plumage 

 as the species ever wears. Tlae scapulars are very dark, the dark areas in the 

 middle of each feather being Vjroad and the margins comparatively narrow. 

 Feathers of the back, neck, and crown also liave broad black medial streaks and 

 narrow margins; and the underparts, except for the middle of the belly, are more 

 heavily and more definitely streaked with black than in any subsequent plumage 

 or plumage-stage. The fact that many feathers of the loral, superciliary, mental, 

 and malar regions are still partly slieathed gives the face a strongly black-and- 

 white appearance that it does not have a few days later. 



In a later paper, G. M. Sutton (1941) adds: "Each of my three 

 captive birds began its postjuvenal molt when approximately eighteen 

 days old. * * * As for the time at which the postjuvenal molt begins 

 in the young of first broods, until we have more facts it is unwise to 

 make further assertions. * * * It is quite possible, therefore, that 

 the young of first broods molt more slowly than do the young of 



