THE MIGRATION OF NORTH AMERICAN BIRDS 30 
are available, but these are sufficient to indicate that the breeding 
range is in the strip of country characterized by more or less stunted 
timber just south of the limit of trees. When it begins its fall migra- 
tion, this bird necessarily covers the full width of its breeding area. 
B4630M 
FIGURE 16.—Breeding and wintering ranges and migration of Harris’s sparrow, an example of a narrow 
migration route through the interior of the country. The heavy broken lines enclose the region traversed 
by the majority of these finches; the light broken line encloses the country where they occur with more or 
less regularity; while the spots indicate records of accidental or sporadic occurrence. 
Then it proceeds almost directly south, or slightly southeasterly, the 
area covered by the majority of the species becoming gradually con- 
stricted, so that by the time it reaches the United States itis most nu- 
merous in a belt about 500 miles wide, extending across North Dakota 
to central Minnesota. MHarris’s sparrows are noted on migration with 
