1138 U.S. NATIONAL MUSEUM BULLETIN 237 part 2 



upper Hudsonian Zone. Though it nests occasionally in the dense, 

 stunted spruces characteristic of this region, it spends most of its time 

 in the brushy willows and birches that fringe the pools and boggy 

 meadows, and the overwhelming majority of nests on record have 

 been on the ground. 



An analysis of hundreds of faunal works, local lists, Christmas 

 censuses, and field notes, shows the center of abundance of tree 

 sparrows in a normal winter to be through central Nebraska, Kansas, 

 Iowa, and Missouri, and across the corn belt to the middle Atlantic 

 States (Baumgartner, 1939). An abnormally mild season finds a 

 greater number wintering in the northern states and southern Canada, 

 while early storms and excessive snows drive them farther south. 

 In Oklahoma, near the southern border of their regular range, I have 

 found their occurrence as variable as Oklahoma weather. In 

 Tennessee, where they occur only rarely, they are generally associated 

 with low temperatures and a blanket of snow (Laskey, 1934b). 



Winter distribution of sexes. — In the course of two seasons of collect- 

 ing at Ithaca, N.Y., it was discovered that the proportion of males 

 ran considerably higher than females during the nonmigratory period, 

 which I arbitrarily limited to the dates December 20 to March 1. 

 In fall and spring the female population equaled or exceeded that 

 of males. Postulating that this indicated segregation of the sexes 

 during the winter, I wrote all the leading museums in the country 

 for lists of their tree sparrow specimens, in the hope of plotting the 

 respective ranges. While many did not have numbers adequate for 

 any conclusions, the larger series corroborated the figures from my 

 personal collecting and banding (indicated in the following list by *), 

 showing that males tend to winter farther northward and females 

 farther southward : 



Part of Range of Number of Winter 



Species Locality Males Females 



Northern Ontario 16 



British Columbia 11 2 



Idaho 16 9 



Michigan 28 5 



*New York (1933-35) 102 31 



Connecticut 21 1 



Central *Indiana (1935) 16 22 



Pennsylvania 26 27 



District of Columbia 17 17 



Kansas 185 158 



Southern *Oklahoma (1940-41) 31 78 



*Oklahoma (1960) 40 113 



