ae | TownsEnD, Labrador Chickadee in Migration. 161 
In order to reach these southern regions, the Labrador Chickadees 
must have flown by and over the resident Acadian Chickadees of 
Nova Scotia, New Brunswick and the northern parts of Maine, 
New Hampshire and Vermont. It would be surprising if some of 
the latter race should not accompany the Labrador form to the 
south or come independently, as has been the case, as I shall show, 
in previous migrations, but all the specimens I have seen, taken this 
winter, belong to the Labrador subspecies. 
It is a familiar gibe that some races cannot be named unless one 
knows the locality where the specimens were taken. Not so in 
the case of nigricans. That the recognition of this subspecies even 
in the field is possible, I have demonstrated, not only by my own 
observations, but by those of others. The differences between 
P. hudsonicus hudsonicus and P. hudsonicus littoralis on the other 
hand are so slight that it would be difficult if not impossible to dis- 
tinguish them in the field. Lvttoralis is slightly smaller and slightly 
browner than hudsonicus. The difference in size is the more impor- 
tant but can only be definitely discovered by measurement. 
The Labrador Chickadee is distinguished from the Hudsonian 
and the Acadian forms by being distinctly dusky instead of brown 
on the back. The mouse-colored cap is generally clearly dif- 
ferentiated from the back which is not so dark. This cap is 
noticeable in life and has been referred to by several observers 
independently. In size, the Labrador Chickadee is intermediate 
between the other two. Its bill is rather heavy, like that of the 
Hudsonian, but about as short as that of the Acadian. It is prob- 
able that intergrades between these three races exist whose exact 
status is in doubt. This is certainly the case between hudsonicus 
and littoralis. 
My late July specimens from Labrador are indistinguishable from 
specimens taken in Massachusetts in December, and it is probable 
that they had already moulted into winter plumage. The first 
winter and later winter plumages in Hudsonian Chickadees are 
practically indistinguishable. A study of specimens of the Acadian 
Chickadee taken at all seasons of the year, shows browner upper 
parts and, with rare exceptions, no distinction in the form of a cap. 
The flanks are, as a rule, browner than in the Labrador or Hudso- 
nian form. Birds in juvenal plumage are slightly darker above. 
