OCTOBER 1989 - City of Boulder

PINE SQUIRE(EL, OR mfCKAEE
Tamias ciurus hudsoni cus
Distribution.--The pine squirrel is a species of coniferous
forests, ranging throughout much of Canada and Alaska, the Rocky
Mountain states, and the northeastern United States, southward along
the Appalachians. In Colorado, the species occurs in the mountains,
high plateaus, and mesas of the western part of the state, including
the Boulder Mountain Parks.
Descrip+ion.--T. hudsonicus is the smallest tree squirrel in
its range. It is &kt to grayish-red above and white below. The tail
is outlined with a broad black band edged with white and there is a
prominent white eyering.
Average (and extreme) external measurements of 13 males and 12
females from -Lake and Chaffee counties are: total length, 320.0 (302-
343) , 319.9 (300-352) ; length of tail, 125.2 (116-135) , 124.1 (117-132) ;
hindfoot, 49.2 (46-51), 48.9 (46-52); ear, 24.6 (19-27), 25.3 (21-29);
weights, 227.8 (202.5-252-0) , 222.7 (193.7-238.6) gr. ; greatest length
of skull, 47.09 (46.0-48.1), 46.93 (46.1-47.8).
Natural History.--The pine squirrel inhabits denser forests of
cooler zones and is restricted only by availability of food and nesting
sites. They have been observed at elevations of 12,000 ft. A certain
sign of their presence is middens (or caches) of cones and cone remnants.
Nests are built in trees out of grass and shredded bark. Pine squirrels
move about on the ground and may burruw a little in earth or snw. They
are active morning and evening. .They do not hibernate, and are solitary.
Food consists mainly of tree seeds, although some dry and cache
fungi. Seeds of spruce and lodgepole pine make up the bulk of the diet..
Females bear a single litter each year, with two to five young
born after a gestation period of 40 days in early to mid-summer. The
female alone cares for the young; lactation lasts seven weeks. Longevity
is 5 to 9 yea&.
T. hudsonicus has few competitors, although deer mice and red-
backez voles may raid their cone caches. They harbor fleas and ticks
and they are potential prey for a number of carnivores, especially
pine martens, hawks, and -1s.
A general survey of the biology of the pine squirrel in the Boulder
Mountain Parks would be of interest. The area may be unique in supporting
sympatric populations of three species of tree squirrels: Abert's
squirrel, the fox squirrel, and the chickaree.
Selected References.--Dolbeer (1973); Finley (1969); Smith (1978).
K. L. S.