Visual display of the Aldo Leopold papers : 9/25/10-4 : Species and Subjects

				
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UNITED STATES DEPARTMENT OF AGRICULTURE 
BUREAU OF BIOLOGICAL SURVEY 
WASHINGTON, D. C. 
ADDRESS REPLY TO 
CHIEF, BUREAU OF BIOLOGICAL SURVEY, 
,.. =,. :o                 (         July 12, 1922. 
AND REFER TO                                     Ti    2   92 
BI-IAZ 
r. Aldo Leopold, 
Forest Service, 
Gas and Electric Building, 
Albuquerque, New Mexico. 
Dear Mr. Leopold: 
Your letter of June 30 inquiring concerning 
the occurrence of the black form of the Abert Squirrel 
is received. 
Individuals of this squirrel with blackish 
underparts appear to occur in various parts of the 
range of the species and are not uncommon. We have 
in the collection a number of specimens with blackish 
underparts from the general region to which you refer, 
and while there seems to be a tendency to develop this 
melanistic condition in parts of the range of the species 
where they are at least more abundant than elsewhere, 
specimens with dark underparts may be expected to occur 
elsewhere along with normally-colored individuals. At 
Loveland, Arkins, and Eastonville, Colorado, melanism 
is complete in some specimens of Sciuras aberti ferreus, 
but here as elsewhere normally-colored individuals occur 
at the same localities. Nelanism as a color variation 
occurs in many animals, and is perhaps rather particularly 
comion in squirrels, as it is well known in a number of 
species. In some squirrels most of the specimens in some 
localities may be entirely black. 
Sincerely yours, 
Chief of Bureau.