4 
MUSEUM BULLETIN NO. 7. 
Mackenzie; Mackenzie river: 1 specimen. 
Yukon Territory, Teslin lake: 4 specimens. 
Wing 
Tail 
Tarsus 
Culmen General colour 
Montana and Idaho 
9.06 
6.56 
1.80 
0.80 
Light 
British Columbia 
8.90 
6.96 
1.77 
0.77 
Slightly darker 
Mackenzie 
8.75 
6.55 
1.70 
0.80 
Light 
Teslin lake, Y. T. 
8.51 
6.33 
1.75 
0.71 
Dark. 
It will be seen that the most southern birds are the largest 
and lightest; the northern smallest and darkest, while those from 
lower British Columbia are intermediate though closer to the 
southern than the northern race. The Mackenzie form, being 
represented by only a single specimen in not very high plumage, 
cannot be definitely placed in the series though it agrees closely 
with the Montana and Idaho specimens. No specimens from the 
type locality of richardsoni (the northeast corner of Rocky 
Mountain park, lat. 53°, long. 115°) being obtainable I assume 
from the above that it ranges up the east side of the Rocky 
mountains and through them south of the International border 
in unmodified form, while the intermountain birds, flemingi , as 
they distribute northward from the boundary, become smaller 
and darker. It is possible that on examination, birds from 
farther north of Teslin lake will exhibit these characters in a 
still more marked degree 
