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



Plumages. — Nelson's sparrow is the smallest of the five races of the 

 sharp-tailed sparrows, the bill in particular being proportionally much 

 smaller. The adult plumage of this race is of a much richer brown 

 with more orange facial markings than the other races, and has a 

 strong buffy wash across the breast which is essentially devoid of 

 streaking. The molts are the same as in the other races. The natal 

 down has apparently never been described. R. R. Graber (pers. 

 comm.) thus describes the juvenal plumage: 



"Males exhibit more ventral streaking than do females. Forehead 

 and crown black, with broad superciliaries and broad irregular median 

 stripe of orange-buff. Nape light chestnut. Feathers of back black, 

 broadly edged with orangish buff. Rump orange buff. Upper tail 

 coverts similar but black along feather shafts. Rectrices black along 

 shaft, edged with olive tinged buff. Remiges blackish, primaries and 

 secondaries edged with olive gray, tertials broadly edged with orangish 

 buff. Coverts black, edged with orangish buff. Lores buffy. Side of 

 head rich orangish buff, with post-ocular strip of black. Underparts 

 orangish buff, richer anteriorly. Sides of jugulum and chest with few 

 fine streaks of black. Ventral streaking variable. Leg feathers dusky 

 and buff." 



The field identification of this race is discussed in the appropriate 

 section of the life history of A. c. caudacuta. 



Enemies.- — Friedmann (1929, 1963) lists nelsoni among the hypo- 

 thetical victims of the brown-headed cowbird on the basis of one 

 hearsay report. The first definite record was made by John Lane, 

 who reported in a letter to Oscar M. Root: "On June 20, 1962 I 

 found a Nelson's sharp-tail nest with 4 eggs plus 1 cowbird egg in a 

 grassy hummock where the yellow rail nests in Dixon's Slough, Gorrie 

 School District, Brandon, Manitoba." 



Voice. — The Nelson's sharp-tail sings both perched and in flight as 

 do the other races. N. S. Goss (1891) writes the song is "uttered at 

 times as it rises and hovers for a moment, but usually from a perch or 

 as it hops from stalk to stalk of the reeds, rushes and coarse grasses." 

 W. J. Breckenridge {in Roberts, 1936) writes that "a low initial note 

 slurs immediately into a high, wheezy, nasal buzz, which terminates 

 in a low, short, grating ^tr." It sings incessantly and with great effort. 

 Song has been reported to July 22. 



Distribution 



Range. — Southern Mackenzie and prairie provinces southeast to 

 Gulf and Atlantic coasts. 



Breeding range. — The Nelson's sharp-tailed sparrow breeds in 

 fresh-water prairie marshes from northeastern.?,British Columbia 



