Geographic Range
Yellow ground squirrels (
Spermophilus fulvus
) can be found as far north as Russia and Kazakhstan, ranging as far west as the Caspian
Sea and the Volga River and as far east as Lake Balkash. The contiguous southern range
spreads down through Uzbekistan, western Tajikistan and Turkmenistan. There are additional
disjunct populations of yellow ground squirrels that are found in northeastern Iran,
Afghanistan, and Kashi, China.
- Biogeographic Regions
- palearctic
Habitat
Yellow ground squirrels live in a terrestrial biome. The habitat of yellow ground
squirrels consists of sand, clay, and loess deserts and semi-deserts. The ground squirrels
also live in forest zones with alkali and saltwort alkali soils. The maximum elevation
of the habitat of these squirrels is 1000 meters. Yellow ground squirrels use natural
and artificial elevated areas to construct their burrows. Titov et al., (2012) found
that man-made disturbed steppe and semi-dessert areas, such as dumping sites and non-structured
cattle pastures in settlements, are where many burrows of yellow ground squirrels
are found. Other sources suggest that the squirrels do not come into contact with
humans or agricultural areas often.
- Habitat Regions
- terrestrial
- Terrestrial Biomes
- desert or dune
- forest
- Other Habitat Features
- agricultural
Physical Description
As their name suggests, yellow ground squirrels have a yellowish upper body with black
tipped hairs that create a finely speckled look. With an adult body mass ranging from
307 to 1428 grams and a body length (not including the tail) ranging from 230 to 370
millimeters, the yellow ground squirrel is the largest-sized genus Spermophilus ground
squirrel. The juvenile body mass of the yellow ground squirrel ranges from 173 to
555 grams. Volodina et al., 2010 reports that the overall average body mass of juvenile
yellow ground squirrels to be 283 grams and the overall average body mass of adults
to be 819 grams. Matrosova et al., 2011 found that the male juvenile average body
mass is 309 grams, the male adult average body mass is 1343 grams, the female juvenile
average body mass is 275 grams, and the female adult average body mass is 856 grams.
The average body mass for male yellow ground squirrels is larger than the average
body mass for female yellow ground squirrels.
- Other Physical Features
- endothermic
- bilateral symmetry
- Sexual Dimorphism
- male larger
Reproduction
Yellow ground squirrels are seasonal breeders, usually breeding during March and April.
The male yellow ground squirrels emerge from hibernation 1-2 weeks before the females.
Beyond this, nothing else is known about the mating habits of this species.
Yellow ground squirrels are iteroparous and reproduce sexually. Female yellow ground
squirrels can produce one litter per year and have an average of 5 pups per breeding
season but can range from 1 pup to 10 pups. The average gestation period is 30 days.
The breeding season usually starts in March and early April, right after they emerge
from hibernation in mid-February. Male yellow ground squirrels emerge from hibernation
first, and about 1-2 weeks later the females will emerge. Female ground squirrels
have about 3 months to mate and gain body weight before entering hibernation in late
June. Juvenile ground squirrels emerge usually in April-May, giving them about 2 months
to gain weight before their first hibernation. The average offspring mass at birth
is 191 grams with a range of 104 to 290 grams. The squirrels will reach their adult
size by the summer after their first hibernation. The female yellow ground squirrels
are capable of reproducing after their first hibernation while the males are not able
to reproduce until after their second hibernation. The average age at reproductive
maturity for the females is one year old and the average age at reproductive maturity
for the males is two years old.
- Key Reproductive Features
- iteroparous
- seasonal breeding
- gonochoric/gonochoristic/dioecious (sexes separate)
- sexual
- viviparous
Yellow ground squirrel pups are born in burrows which allows for protection from predators.
The ground squirrel pups are born undeveloped and require care and feeding from their
mothers. The female squirrels protect and care for the young, having extended social
contact with their young up until their first hibernation. The mothers teach the pups
how to make alarm calls. It is not apparent that the males are involved except during
the mating process.
- Parental Investment
- altricial
- female parental care
-
pre-hatching/birth
-
provisioning
- female
-
protecting
- female
-
provisioning
-
pre-weaning/fledging
-
provisioning
- female
-
protecting
- female
-
provisioning
-
pre-independence
-
provisioning
- female
-
protecting
- female
-
provisioning
Lifespan/Longevity
Yellow ground squirrels live between five to six years in the wild. Once the female
ground squirrels reach sexual maturity, around one year of age, the mortality rate
increases. Seventy percent of female ground squirrels die before their third hibernation
and eighty-seven percent die before their fourth hibernation. The longest captive
lifespan for members of the genus
Spermophilus
is 11 years.
Behavior
Yellow ground squirrels live in burrows underground and are active during the day. The squirrels typically have low population densities of about 3 to 10 individuals per hectare. The female ground squirrels tend to stay close to their natal burrows whereas the males move farther away.
Yellow ground squirrels usually emerge from hibernation in mid-February when the vegetation
starts to green up. In the middle of March the ground squirrels begin mating and during
this time, they do not eat very much. After mating, the squirrels will spend all day
eating and they gain weight quickly. When the sun rises, the ground squirrels exit
their burrows and begin to eat the vegetation nearby. Around the middle of the day,
as it warms, the squirrels will return to their burrows. Later in the afternoon, the
ground squirrels will come back out of the burrow for a short period. In 24 hours,
the ground squirrels will have consumed, on average, 275 grams of vegetation. The
squirrels continue to eat until the availability of suitable forage declines, usually
early June, and then they enter hibernation.
- Key Behaviors
- fossorial
- diurnal
- motile
- hibernation
Home Range
Communication and Perception
Yellow ground squirrels have an advanced sociality compared to the smaller species
in the genus
Spermophilus
. They have burrows in close proximity to each other which allows them to hear the
alarm calls of neighbors and respond to them. The alarm call is the most common and
the loudest call used by yellow ground squirrels. The structure of the alarm calls
of the ground squirrels is the same in all predatory situations, such as humans, some
harmless animals, terrestrial predators, and raptors. Juvenile ground squirrels have
an alarm call that is very close to the alarm call of the adult squirrels. The pitch
of the alarm call is lower in the juveniles than in the adults, which is not common
among mammals.
Food Habits
Yellow ground squirrels are herbivores. The ground squirrels that inhabit the desert
and semi-desert areas feed on desert vegetation which is their only source of metabolic
water. The main sources of vegetation that yellow ground squirrels consume is bulbous
bluegrass (
Poa bulbosa
),
Carex
grasses (
Carex hostii
), and a flowering plant (
Malcolmia turkestanica
). Yellow ground squirrels are active as long as the period of vegetation lasts. During
the mating season the ground squirrels don't spend much time eating. After the mating
season the squirrels spend most of the day eating to gain weight before hibernation.
- Plant Foods
- leaves
Predation
Yellow ground squirrels are one of the main prey of eastern golden eagles (
Aquila chrysaetos
), imperial eagles (
Aquila heliaca
), and steppe eagles (
Aquila nipalensis
). These squirrels warn others of predators through an alarm call. Steppe polecats
(
Mustela eversmanii
) and marbled polecats (
Vormela peregusna
) hunt in burrows and prey upon young ground squirrels. These polecats do not eat
adults. Matrosova et al. (2007) state that there are cases of infanticide where neighbors,
both male and female ground squirrels, will kill the young. They further suggest that
because some predators that only attack juvenile squirrels, the young may mimic the
adults alarm calls as a way to discourage such juvenile-specific predators.
Ecosystem Roles
Yellow ground squirrels eat desert grasses. The squirrels provide a food source for
the predators that hunt them, such as eagles and polecats. Common parasites of yellow
ground squirrels are northern rat fleas (
Nosopsyllus fasciatus
), sucking lice (
Enderleinellus propinquus
and
Linognathoides laeviusculus
), ticks (
Hyalomma asiaticum
), and protists (
Eimeria airculensis
,
Eimeria berkinbaevi
,
Eimeria deserticola
, and
Eimeria susliki
).
- Northern rat flea Nosopsyllus fasciatus
- Lice Enderleinellus propinquus
- Lice Linognathoides laeviusculus
- Protist Eimeria airculensis
- Protist Eimeria berkinbaevi
- Protist Eimeria deserticola
- Protist Eimeria susliki
- Tick Hyalomma asiaticum
Economic Importance for Humans: Positive
Yellow ground squirrels are hunted by humans. The squirrels are often hunted commercially
and sold for profit. There was not much information found on the price, uses, or locations
of the hunting.
- Positive Impacts
- food
Economic Importance for Humans: Negative
There are no adverse economic effects of yellow ground squirrels on humans.
Conservation Status
There is no special status listed for yellow ground squirrels for the CITES appendices
or the United States Endangered Species Act list, but it is listed as "Least Concern"
on the IUCN Red List. Commercial hunting is a potential threat and has affected some
populations in areas of Russia and Kazakhstan but has not caused a substantial decline
in the population. There are no conservation acts to protect the yellow ground squirrels.
Additional Links
Contributors
Rebekah Shorter (author), Radford University, Cari Mcgregor (editor), Radford University, Zeb Pike (editor), Radford University, Karen Powers (editor), Radford University, April Tingle (editor), Radford University, Jacob Vaught (editor), Radford University, Tanya Dewey (editor), University of Michigan-Ann Arbor.
- Palearctic
-
living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- terrestrial
-
Living on the ground.
- desert or dunes
-
in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.
- forest
-
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
- agricultural
-
living in landscapes dominated by human agriculture.
- iteroparous
-
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
- seasonal breeding
-
breeding is confined to a particular season
- sexual
-
reproduction that includes combining the genetic contribution of two individuals, a male and a female
- viviparous
-
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
- altricial
-
young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.
- female parental care
-
parental care is carried out by females
- fossorial
-
Referring to a burrowing life-style or behavior, specialized for digging or burrowing.
- diurnal
-
- active during the day, 2. lasting for one day.
- motile
-
having the capacity to move from one place to another.
- hibernation
-
the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.
- food
-
A substance that provides both nutrients and energy to a living thing.
- herbivore
-
An animal that eats mainly plants or parts of plants.
- folivore
-
an animal that mainly eats leaves.
- endothermic
-
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
- bilateral symmetry
-
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
- tactile
-
uses touch to communicate
- chemical
-
uses smells or other chemicals to communicate
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