torically limited ranges. The round-tailed ground squir-
rel has lost about half of its historic range to urban land
conversion.
It seems that island endemism and /or habitat loss is
associated with most imperiled status classifications for
species and subspecies. Habitat loss is most apparent in
the forest encroachment at the dry northwestern edge of the
range of intermountain prairie dogs, desertification at the
southwestern edge of the range, and anthropogenic con-
version of these dry northern and southern grasslands.
Continental ground squirrels and prairie dogs that are less
dependent on dry grasslands, including those found in
mountainous areas, populations in the far north, west of
the Coast range, in shrubsteppe (or high desert), in tallgrass
prairie, or adapted to a wide variety of habitats generally
are less threatened. Habitat conversion by replacement of
deep-rooted, perennial bunchgrasses with invasive annual
monocots and dicots is a concern throughout, however, but
especially in north-central shrubsteppe habitats.
Understanding how this broad picture of intertwined
habitat loss and population fragmentation affects ground
squirrels requires that we consider how species attributes
related to subterranean burrow construction and energy
budgeting place limits on adaptation to habitat change.
Within this context, predation, disease, and genetic struc-
turing also influence conservation status and long-term
prospects for these species.Energetic AdaptationsGiven that diurnal ground squirrels are an important food
source for avian and mammalian predators, one might
expect “top-down” predation to limit population growth.Conservation of Ground Squirrels 467Table 39.1 North American species of Cynomysand Spermophilus,and Spermophilusspp.
elsewhere known to be endangered or vulnerableGlobal conservation
Common name Scientific name IUCN status status rankGunnison’s prairie dog C. gunnisoni
White-tailed prairie dog C. leucurus
Black-tailed prairie dog C. ludovicianus Vulnerable
Mexican prairie dog C. mexicanus Imperiled
Utah prairie dog C. parvidens Critically imperiled
Uinta ground squirrel S. armatus
California ground squirrel S. beecheyi
Belding’s ground squirrel S. beldingi
Idaho ground squirrel S. brunneus Endangered Imperiled
Merriam’s ground squirrel S. canus Apparently secure
Columbian ground squirrel S. columbianus
Wyoming ground squirrel S. elegans
Franklin’s ground squirrel S. franklinii Vulnerable
Golden-mantled ground squirrel S. lateralis
Mexican ground squirrel S. mexicanus
Mohave ground squirrel S. mohavensis Vulnerable Imperiled or vulnerable
Piute ground squirrel S. mollis
Arctic ground squirrel S. parryii
Richardson’s ground squirrel S. richardsonii
Cascade golden-mantled ground squirrel S. saturatus
Spotted ground squirrel S. spilosoma
Round-tailed ground squirrel S. tereticaudus
Townsend’s ground squirrel S. townsendii Data deficient Apparently secure
Thirteen-lined ground squirrel S. tridecemlineatus
Rock squirrel S. variegatus
Washington ground squirrel S. washingtoni Vulnerable ImperiledSOURCE: IUCN (2003); NatureServe (2004).
NOTES: C.Cynomys; S.Spermophilus.IUCN red list status: Vulnerablefacing a high risk of extinction in the medium-term
future. Data deficientinadequate information to assess risk of extinction based on distribution and /or population status. Global
conservation status rank (NatureServe G1– G3): Critically imperiledat very high risk of extinction due to extreme rarity (often
5 or fewer populations), very steep declines, or other factors. Imperiledat high risk of extinction due to very restricted range,
very few populations (often 20 or fewer), steep declines, or other factors. Vulnerableat moderate risk of extinction due to a
restricted range, relatively few populations (often 80 or fewer), recent and widespread declines, or other factors. Apparently
secureUncommon but not rare; some cause for long-term concern due to declines or other factors. Unrankednot yet
assessed. If no rank is given, the species is considered to be Secure (common, widespread, abundant ).