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Gunnison's prairie dog
Gunnison's prairie dog is a stout-bodied creature whose total length
varies from 309 to 373 mm. Males are larger than females on average,
and subspecies differ slightly in color and size. The dorsal pelage
of these animals is yellowish buff intermixed with blackish hairs,
while the top of the head, sides of the cheeks, and eyebrows are
noticeably darker than the other portions of the pelage. Two annual
molts occur in these animals-- one in the spring and another in the
fall.
The spring molt begins anteriorly and proceeds posteriorly until the
tail hair is renewed. In contrast,
the winter coat renewal, which is usually complete by mid-September,
begins in the posterior region of the body and progresses anteriorly. Cynomys gunnisoni
has a much shorter tail - 39 to 68 mm - than other prairie dogs, and
it is uniquely colored. The proximal half of the tail is the same
color as the dorsal pelage; however, the distal half is grayish with
grayish-white hairs appearing at the terminus. This character is very useful in differentiating
C. gunnisoni from other white-tailed species, which possess pure
white hairs on `the distal half of their tails.
It should be noted that one of the most interesting physical
characteristics of these animals is the placement of their eyes.
Their eyes, positioned on the sides of the head, appear to be
adapted for detecting movement over a wide arc, and this allows
these prairie dogs to detect predators with greater success.
Reproduction
The onset of reproduction is somewhat variable and dependent on
latitude, elevation, and seasonal variation. Females are capable of
reproducing at 1 year of age and bear a single litter per year
(average size is 4.78 young) after a 30 day gestation period.
Previous studies have shown that parturition occurs between the
months of April and early May. Young remain underground for about a
month after birth. Consequently, little is known about growth and
development during this period. During the
lactation period newborns nurse from one of five pairs of mammae--
two pectoral and three inguinal. After the young begin emerging from
the nesting burrow, nursing soon ends, and the offspring must become
independent and feed on surrounding vegetation . After all the
offspring are weaned, the mother leaves them in the nesting burrow
and establishes herself in another burrow. Soon thereafter, the
young leave the nesting burrow and disperse to other unoccupied
burrows.
Males of this species have a baculum which resembles that of ground
squirrels (genus Spermophilus), and therefore, males are often
described as spermophile-like.
Behavior
Cynomys gunnisoni is often found in semi-social aggregations; yet,
colonies of these mammals are generally smaller than those of other
species of prairie dogs and usually consist of fewer than 50 to 100
individuals. Interestingly, in open habitats where Gunnison's
prairie dogs have been afforded protection, the colonies become
quite extensive and densely populated. Overall, the social
organization of these creatures is loosely knit and more closely
resembles that of ground squirrel aggregations than it does more
highly structured organizations of other prairie dogs. Social
structure consists mainly of mother-offspring relationships, while
adult males live somewhat apart from females and offspring during
the post-natal period. Territoriality is rarely
exhibited by a male C. gunnisoni; older males may defend a small
area near their burrows, but they often feed alongside other members
of the colony without conflict. In
contrast, a female C. gunnisoni is highly territorial and aggressive
during the post-natal period. However, as soon as her pups emerge
above ground, the aggressive behavior subsides. Gunnison's prairie
dogs are strictly diurnal, and their greatest periods of activity
occur in the early morning and late afternoon. Above ground
activities mostly include feeding, playing, and grooming; however,
these animals are constantly on the lookout for possible danger
while venturing out of their burrows. Cynomys gunnisoni will sit up
on its hind feet to survey its surroundings from the tops of the
dirt mounds that form at burrow entrances.
Although several physical attributes can be used to distinguish C.
gunnisoni from other species of prairie dogs, vocalizations -
particularly alarm barks - are species specific and permit
identification. Besides the alarm
call, which consists of a series of repetitive barks, C. gunnisoni
is capable of generating four other calls: raspy chatter, a contact
call given under peaceful surroundings; a snarl or rasp, an
aggressive call; a growl, another aggressive call; and a scream, an
injury or escape call. A study of the
alarm calls of adult C. gunnisoni from three separate Arizona towns
during April-September 1977 uncovered some very interesting facts.
First, the alarm calls of Gunnison's prairie dog have diverged into
local dialects and therefore differ between the three studied
locations. Second, within a particular C. gunnisoni colony there
were significant differences in the calls announcing the presence of
different predators -- the different predators used in the study
were humans, dogs, coyotes, and hawks. In addition, a significant
difference in calls existed when the same predator was announced in
different colonies. Third, the number of syllables and the total
call length were strongly correlated with the complexity of the
habitat-- the more complex the habitat was in terms of vegetation,
rocks, and tree stumps, the longer the call became and the more
syllables it contained. This phenomenon may be explained by the fact
that sound attenuates faster in a more complex habitat, and a longer
call with a larger number of syllables may be needed in a more
complex habitat to maintain the same alarm function as a shorter
call in a less complex habitat.
Above ground activity of C. gunnisoni occurs between late March and
October, and the winter months comprise a period of inactivity for
C. gunnisoni in most locations. Snowfall forces many of these
creatures to remain underground and to survive off the fat stores
they developed over the summer months. There is little evidence
regarding hibernation in these animals, but periods of inactivity,
which may last several months, support the contention that
Gunnison's prairie dogs hibernate, at least in the colder parts of
their range. Additional evidence supporting this claim comes from a
laboratory colony observed during the winter months, in which
members entered short periods of deep sleep with low food intake. No
information regarding the body temperature of prairie dogs in the
wild during the winter months is currently available, however.
Food Habits
The masticatory muscles among members of the genus Cynomys are,
proportionally, the stoutest and most highly developed among the
Nearctic Sciuridae, and the crown height of their cheekteeth equals
or exceeds that of all other Nearctic Sciuridae. These characteristics reflect the adaptation of
Gunnison's prairie dogs to an almost exclusively graminivorous diet.
In addition, analyses of the stomach contents of Gunnison's prairie
dogs have shown that these creatures also eat forbs, sedges, and
shrubs.
In captivity they should be offered a complete diet of rodent lab blocks, and rat or mouse
mix, with bits of fruit or veggies regularly. Cheerios or wheat
bread are great treats, in small quantities. Do NOT feed chocolate,
fried foods, salted foods, candy or junk food! They may enjoy
crickets and mealworms if they are captive bred, never feed wild
insects as they may carry parasites. Vitamins, like Nutri-Cal are a good addition to their diet, and added calcium
during nursing and growth due to demands on their systems at those
times, but take care not to overdo it. Water bottles should be used
to proved constant, clean water. Ceramic or stoneware food dishes
work well for keeping seeds or fresh foods off the floor, and a wire
mesh hopper that allows them to eat the lab blocks through without
extra waste.
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