TREE SPARROW 1139 



During late February and March ol" 1960 Oklahoma had a period 

 of severe cold and heavy snows which brought in an unprecedented 

 number of tree sparrows. During a single month I handled almost 

 200, most of which repeated several times a day. When my hands 

 were not too numb nor my glasses fogged, I noted external sex 

 characteristics {see Plumages), and recorded a tentative sex identifi- 

 cation. While some were not differentiated sharply enough even to 

 hazard a guess, I have 113 cards marked as unquestionably female 

 with narrow crowns heavily streaked with dark shafts, and 40 possibly 

 inmiature males or adult females, the group most difficult to sex by 

 external criteria. Of the 168 tree sparrow^s I banded between 1948 

 and 1959, I designated 110 as females, the rest an indetermined 

 proportion of adult females and males. 



Migration. — Between the winter range and the breeding groiuids of 

 the tree sparrow stretch almost 1,000 miles of territory in which the 

 species occurs only as a migrant. Alaskan bu'ds must travel some 

 3,000 miles to reach their destination, but most of the birds that 

 winter through central United States may be assumed to journey 

 between 1,500 and 2,000 miles to nest. 



In Oklahoma, in the southern part of their range, the first evidence 

 of spring movement comes in late February, and the majority are 

 normally gone by mid-March. Following the severe storms of 

 March 1960, new birds continued to visit my banding station at 

 Stillwater until March 26, and a dozen or more individuals remained 

 until AprU 5. 



In the Mississippi Valley, Cooke (1888) found the crest of the 

 migration to pass between March 30 and April 8, Eaton (1910) 

 lists migration in New York State chiefly through late March and 

 the first three weeks of April; the latest is May 15 at Ithaca (Edmin- 

 ster, MS.). Travehng primarily by night, flocks of five or ten or 

 hundreds arrive in waves, remain a few days or weeks, and drift away 

 a few at a time. 



The sequence of migrants and winter residents as presented by 

 W. P. Smith (1926), Horsey (1926), and Austin (1932b), agrees 

 substantially w4th the movements observed at Ithaca, N.Y. Five 

 years of records from Dr. A. C. Frazer's station and a check group of 

 54 regular winter residents at my owm traps showed parallel behavior: 

 A sprinkHng of the winter residents (birds banded between December 

 20 and March 1) disappeared during mid-February, which probably 

 represents local wandering rather than true migration. During the 

 third week of February a number of new birds were banded and a 

 few more winter residents drifted away, consistently enough at both 

 stations to suggest the vanguard of true migration. March saw a 

 steady increase in migrants and departure dates of winter residents. 



