264 Cynomys ludovicianusBlack-tailed prairie dogs are social and live in large com-
plexes called towns (or colonies). Most burrows can be rec-
ognized by a ring of excavated soil around the entrance and
a small mound; some peripheral burrows lack any mound.
Burrows are modest, with two entrances (but occasionally
as many as six). There is a nest within lengthy burrows (typ-
ically exceeding 10–15 m long and penetrating 2–3 m deep).
Black-tailed prairie dog colonies vary considerably in size
and density, but some are known to extend for many kilo-
meters; a prairie-dog town in Oklahoma (USA) was esti-
mated to be 35 km in length, and such descriptions are com-
mon in the early literature. C. ludovicianus is highly social.
Colonies of C. ludovicianus consist of territorial family
groups called coteries. Coterie size (i.e., the number of
adults and yearlings living in the same territory) can be as
small as 2 or as large as 26, but the typical coterie contains 1
adult male, 2–3 adult females, and 1–2 yearlings of both
sexes. Coterie territories average about 0.3 ha in size, and
their boundaries remain remarkably stable over time. A
typical coterie has approximately 70 burrows, and all mem-
bers of a coterie can use any of these entrances, with one
exception: pregnant and lactating females vigorously defend
nursery burrows. Females within the same coterie are al-
most always close kin (mothers, daughters, sisters, nieces,
etc.). The coterie structure reduces this species’ eff ective
population size, due to matrilineal relationships, and fi ne-
scale genetic diff erentiation is detectable. Playing, greeting
by sniffi ng anal and oral glands, kissing, and allogrooming
are affi liative behaviors shared between group members (ex -
cept when females are nursing their young), but aggression—
including physical combat—is directed at individuals from
outside the coterie. The territorial two-syllable “jump-yip”
call is given as an individual stands on hind feet and throws
its front legs and head upward, and this call commonly elic-
its similar responses from members of its own and adjacent
coteries. Infanticide is the primary source of juvenile mor-
tality, accounting for the loss of 39 percent of the juveniles,
especially when in the burrow or immediately after emer-
gence. Sources of infanticide (in order of importance) are
marauding females that actively seek and kill the off spring
of other coterie members, female abandonment of their
own off spring, immigrant male takeovers of coteries, and
immigrant females. Weaning usually is not complete until
one to three weeks after the juveniles fi rst emerge from the
nursery burrow, and communal nursing is common follow-
ing this fi rst emergence. Survivorship is about 50 percent in
the initial year of life, with a maximum longevity of 8 years
for females and 5 years for males.
C. ludovicianus can often be seen feeding on grasses,
forbs, thistles, fl owers, cactus, and seeds; individuals also
clip vegetation without ingestion, in an eff ort to maintain
lines of sight. Individuals sit on their haunches or stand up-
right on two feet to scan for predators. Vigilance functions
mostly to improve the probability of detecting a predator,
but it also monitors the activities of nearby conspecifi cs
(many of whom might be infanticidal). Alarm calls are given
in response to the large-bodied mustelids (badgers [Ta x ide a
taxus], weasels [Mustela], and black-footed ferrets [Mustela
nigripes]), bobcats (Lynx rufus), coyotes (Canis latrans), snakes,
and raptors that function as this species’ principal preda-
tors. The vocal repertoire of C. ludovicianus is robust, with at
least 12 known sounds, but only “jump-yips” and alarm calls
are common. Black-tailed prairie dogs benefi t from a large
colony size by their ability to detect predators early and to
spend more time feeding and less time being vigilant. Their
area of occupancy has been reduced from about 40 million
ha historically to about 766,400 ha, a decline of 98 percent.
Habitat loss is considered a major threat as signifi cant
amounts of grassland (perhaps 40%) are being converted to
agriculture. Urbanization also continues to remove sizeable
amounts of habitat. Large and recently isolated fragments
near other prairie dog colonies, fl at areas, and those with
substantial grass cover are most likely to support prairie dog
populations in urban areas. Historically, black-tailed prairie
dogs were hunted occasionally for food, often for target
practice or sport, and for pest removal; shooting remains
popular in some portions of their range. They were often
(and sometimes still are) viewed as a signifi cant competitor
for forage or as a threat to livestock, due to their open bur-
rows that grazing animals might step into; both of these
concerns are exaggerated. As a potential pest, black-tailed
prairie dogs were often poisoned in the 1900s in an attempt
to extirpate them within their small isolated range, result-
ing in massive declines. Poisoning continues in some por-
tions of their range. Some researchers, however, consider
Cynomys to be important for soil quality, as a vital contribu-
tor to other wildlife habitats, and as an indicator of ecosys-
tem health. Black-tailed prairie dogs are highly susceptible
Cynomys ludovicianus. Photo courtesy Elaine Miller Bond. to outbreaks of sylvatic (bubonic) plague, a bacterial disease