1040 U.S. NATIONAL MUSEUM BULLETIN 237 paet 2 



into distinct, stable winter flocks with mutually exclusive foraging 

 territories." She continues: 



The junco flock is an association of birds which is firm in the identity of the 

 individuals associated. * * * In a given small area a single group will be seen 

 and no^other. The formation of firm associations and the occupation of definite 

 foraging areas take place at once among the earliest arrivals; it becomes obvious 

 as soon as the first migrants are marked. The late comers are integrated into 

 existing groups. The flock thus formed does not fly about as a unit, however. 

 There appears to be no limit to the size of a foraging group. It may include the 

 whole flock or it may consist of a single bird. The entire flocking procedure is 

 marked by the continual forming and dissolving of groups of unpredictable size 

 consisting of individuals that consort together and are daily visitors at the feeding 

 sites. 



Distribution 



Range. — Western and northern Alaska, Mackenzie, northern On- 

 tario and Labrador south to northern Mexico and the Gulf coast. 



Breeding range. — The northern slate-colored junco breeds from 

 western and northern Alaska (Brooks Range, Kobuk River, Yukon 

 Delta), central Yukon (OgUvie Range), northwestern and central 

 Mackenzie (Mackenzie River Delta, Fort Anderson, Fort Reliance), 

 northern Manitoba (ChurchUl), northern Ontario (Shagamu River), 

 northern Quebec (Richmond Gulf), Labrador (Tikkoatokuk Bay), 

 and Newfoundland south to south central Alaska (Lake Clark, Sel- 

 dovia. Prince William Sound), southern Yukon (Lake Marsh), north- 

 eastern British Columbia (Muncho Pass), central Alberta (Edmonton 

 district), central Saskatchewan (McLean), southern Manitoba (Trees- 

 bank), central Minnesota (eastern Marshall County, Minneapolis), 

 southeastern Wisconson (Jefferson, Burlington), central Michigan 

 (rarely south to Ingham County), southern Ontario (London), north- 

 eastern Ohio (Geauga and Trumbull counties), northern and western 

 Pennsylvania (Pocono Mountains; intergrades with J. h. carolinensis 

 in Appalachian Mountains), southeastern New York (Hardenbiu-g, 

 Bald Mountain near Dover) , Connecticut (Union; rarely to Hadlyme) , 

 and Massachusetts. 



Winter range. — Winters chiefly south of the breeding range and 

 east of the Rocky Mountains, but sparsely to the westward, from 

 southeastern Alaska (Juneau), southern British Columbia (North 

 Vancouver, Okanagan Landing), northwestern Montana (Fortine), 

 southern Saskatchewan (Eastend, McLean), southern Manitoba 

 (Brandon, Winnipeg), northern Minnesota (Bagley, Duluth), western 

 Ontario (rarely north to Port Arthur), northern Michigan (rarely 

 north to Munising and Sault Ste Marie), central Ontario (Algonquin 

 Park, Ottawa), southern Quebec (Montreal; Anticosti Island, rarely), 

 and Newfoundland (Avalon, Tompkins) south to northern Baja 



