HARRIS' SPARROW 1251 



(1959) notes that these birds were found originally only in the upper 

 Missouri River valley, but that during the past 60 years they have 

 spread eastward and are now regular, though uncommon, migrants 

 down the upper Mississippi River valley as well. 



The northward movement begins in the southern parts of the 

 winter range in late February and early March, surges into Nebraska 

 and Iowa by mid-March, and into southeastern South Dakota by 

 late March (Youngworth, 1959). Then occurs a pause first noted by 

 Cooke (1913) before the birds move on into the Dakotas and Min- 

 nesota in late April and May (Swenk and Stevens, 1929). Thus 

 no appreciable migration is evident beyond the winter range until 

 May. As Orin A. Stevens (1957) notes: "In the spring Harris' 

 Sparrows reach Fargo, North Dakota about May 7 * * * and are 

 present about two weeks. It seems evident that both their arrival 

 and length of stay are delayed by cold weather, and that their de- 

 parture is hastened by a warm wave. They are restless and there 

 are few repeat records of individual birds." 



In their detailed study of the species, Myron H. Swenk and Orin A. 

 Stevens (1929) note: "The vanguard arrives with remarkable uni- 

 formity during the first week in May or shortly thereafter at points 

 over an area extending from the Dakotas to Minnesota and Manitoba. 

 The passage of the vanguard across Saskatchewan, Alberta, and 

 Northwest Territory to the breeding grounds of the species is made 

 during the last half of May, though it is probably the middle of 

 June before the migration of all the birds is completed." 



Banding records show that some, at least, of the Harris' sparrows 

 follow the same migration routes in spring and fall and in consecutive 

 seasons, with occasionally the same stopovers. Other individuals, 

 recovered from 25 to 100 miles on either side of their place of banding 

 during a subsequent migration, manifestly shifted their migration 

 path. Repeat records at banding stations (Swenk and Stevens, 1929) 

 show that individuals may remain at given stopovers from 1 to 5 

 days during spring migration, averaging 1.5 days. In fall the periods 

 are considerably longer, averaging 7 or 8 days, sometimes a month. 



The speed at which Harris' sparrows migrate in spring is indicated 

 by several recoveries in the Bird Banding files. A bird banded at 

 Aberdeen, S. Dak., May 9, 1933, was recovered 325 miles away at 

 Winnipeg, Man., 5 days later, having averaged 65 miles per day. 

 Another banded at Ipswich, S. Dak., May 7, 1940, was taken 370 

 miles northward at Lake Manitoba 8 days later, having averaged 

 46 miles per day. 



Nesting. — Almost a century after the discovery of Harris' sparrow 

 on the Missouri prairies, the eggs of this handsome bird were still 

 unknown to science. While a nest with young and fledglings just out 



