Cynomys ludovicianus 263Cynomys ludovicianus (Ord, 1815)
Black-Tailed Prairie Dog
description: Black-tailed prairie dogs are buff to brown to
cinnamon on the dorsum, with a pale buff to white venter.
The region above the eyes and around the snout can be paler
than other parts of the dorsum. The tail is dark brown to
black on the distal third.
size: Female—HB 373.5 mm (354.5–397.8 mm); Mass 819 g (n
= 430) in autumn, 689 g (n = 276) in winter, and 696 g (n = 613)
in spring.
Male—HB 373.5 mm (354.5–397.8 mm); Mass 905 g (n =
217) in autumn, 750 g (n = 149) in winter, and 801 g (n = 281) in
spring.
Males are 10–15 percent heavier than females.
distribution: The black-tailed prairie dog is found in a few
localities across a broad area: extreme southern Saskatche-
wan (Canada); and Montana to western North Dakota and
south to New Mexico and western Texas. It was recently
reintroduced to southeastern Arizona (USA) and northeast-
ern Sonora and northern Chihuahua (México).
geographic variation: Two morphologically similar sub-
species are recognized.
C. l. ludovicianus—covers the vast majority of the range.
There are no external diff erences between the
subspecies.
C. l. arizonensis—southwestern portion of the range.conservation: IUCN status—least concern. Population
trend—decreasing. C. ludovicianus is a recent candidate for
threatened status in the USA, and this species is considered
threatened in México.habitat: Black-tailed prairie dogs occupy open fl at or gen-
tly sloping grasslands with low and relatively sparse vegeta-
tion, in areas with fi ne- to medium-textured soils. They are
commonly found in shortgrass and mixed-grass prairies in
the western portion of their range; and in tallgrass prairies
in the eastern portion, primarily where grass height is re-
duced by grazing, mowing, or agriculture. This species can
occur in overgrazed livestock range and in open vacant lots
at the edges of urban areas.natural history: C. ludovicianus is diurnal and active
throughout the year, except during periods of prolonged
and exaggerated cold, when individuals may enter tempo-
rary torpor and remain underground. Adults emerge in
March or early April and enter hibernation in July or Au-
gust, whereas juveniles remain active into October or No-
vember. Mating occurs during a two- to three-week period,
when females enter a single day of estrus and copulate un-
derground. The breeding season varies with latitude. This
species is polygynous; multiple paternity occurs occasion-
ally (less than 25%), and a fi rst-male advantage exists for
sires. Most males and females copulate for the fi rst time
when they are almost 2 years old; however, a few females
and males (less than 10%) produce young when they are
yearlings. Males are more likely to delay their fi rst repro-
duction than females. After a gestation of 34–35 days, the
young are born in the burrow. Females can wean one litter
per year; although most adult females mate, only about 89
percent successfully wean a litter, and just 54 percent of
yearling females are successful. Litters of three or four
(range = 1–6) young appear aboveground at 6 weeks and are
weaned soon afterward. Natal dispersal is male biased, with
most males, when they are yearlings, leaving their natal
area during the late spring or early summer; breeding dis-
persal by older adult males is also common. Mean lifetime
reproductive success is higher in males (7.1 weaned off -
spring) than females (3.9 weaned off spring), but it is more
variable for males. Female reproductive success is positively
impacted by the previous year’s rainfall and by breeding
early in the season. Heavy long-lived animals have the high-
est lifetime reproductive success.