OCTOBER 1989 - City of Boulder

Odocoileus hemionus
Distribution--The mule deer is a western species, ranging from the
Pacific Coast eastward to the Great Plains and from southern Alaska
to central Mexico. In Colorado it occurs statewide, wherever suitable
forest edge, woodland, or brush habitat occurs. It is a common
species throughout the ' Boulder Mountain Parks.
Description--Mule deer are of moderate size, standing 1 meter tall
at the shoulder. They have a coarse pelage that is reddish to yellowish
brown in sunmrer and dark brown to gray speckled with white in winter.
The large ears are black on their front borders, and there is a white
rump patch, a narrow, black-tipped tall, and males have dichotomous
antlers. Average weights of bucks are about 120 kg., and of does 60
to 70 kg. Total length is 1,200 to 1,800, and the tail is 100 to 230
nnn. long. Basilar length of skull ranges from 200 to 290, and
zygomatic breadth is 90 to 135.
Antlers grow on males and are a rare freak on females. Mature
deer normally have five tines on each side. Fewer tines indicate
youth, disease, or old age,andmore indicate parasite damage or injury.
Most mature racks measure 60 to 90 cm. across and are shed in February
or March of each yeart replacement begins immediately.
Natural History-4ule deer are browsers, feeding on the terminal
shoots of a variety of shrubs. The most important foods In summer are
aspen, willow, and vacchium, and winter foods are skunkbush, sagebrush,
bitterbrush, and mountain mahogany, with a preference for recent growth.
No one browse species furnishes all neec?ed nutrients at a .given season.
A variety of browse species'is essential to a healthy population.
Mule deer migrate between summer and winter range. Summer range
for bucks may extend above timberline, but does and fawns remain
somewhat lower, Deer are driven to winter range by snows in about
October and move back up with the melt in spring. Deer typically
concentrate on winter range, but the high year-round populations on the
Boulder Mountain Parks are atypical. That herd very much deserves
the studies now planned and in progress.
Rut begins in November; bucks' necks swell and sparring begins.
Breeding is polygamous. The peak of the breeding season is mid- to
late November. Both bucks and does begin breeding at about 18 mcnths.
Gestation is about 200 days, with peak of fawning in mid-June. Birth
weights are 4 to 5 kg. The precocial fawns are covered with spots which
disappear at the end of the first summer. Fawns are kept kidden; mothers
return to them only to feed them. After a few weeks, fawns follow the
mother as she feeds. Does usually are mutually intolerant when with'
fawns, but there are reports of does cooperating to defend fawns from
coyotes. Fawns are weaned in autumn and are independent of their mother
at 12 months.
Predators of the mule deer include coyotes, bobcats, mountain
lions, black bear, golden eagles, and dogs. Deer serve as host to a
variety of parasites. Hunting is now the principal check on populations.
In 1975, nearly 128,000 deer were harvested .in Colorado, most of them
mule deer; of those, only 128 were taken from Boulder County.
Selected References-Anderson and Medin (1979); Loveless (1967);
Taylor (1956) ; Wallmo (1982).