The Cascade golden-mantled ground squirrel (''Callospermophilus saturatus'') is a species of

rodent Rodents (from Latin , 'to gnaw') are mammals of the Order (biology), order Rodentia (), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are roden ...

in the family

Sciuridae Squirrels are members of the family Sciuridae, a family that includes small or medium-size rodents. The squirrel family includes tree squirrels, ground squirrels (including chipmunks and prairie dogs, among others), and flying squirrels. ...

, in the order

Rodent Rodents (from Latin , 'to gnaw') are mammals of the Order (biology), order Rodentia (), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are roden ...

ia. It is the largest species of the three within the genus ''

Callospermophilus ''Callospermophilus'' is a genus of ground squirrel from North America. Etymology ''Callospermophilus'': gr. καλλος ''kallos'' – beauty, from καλος ''kalos'' – beautiful; genus '' Spermophilus'' F. Cuvier, 1825 Species The ge ...

.'' It is found in the

Cascade Mountains The Cascade Range or Cascades is a major mountain range of western North America, extending from southern British Columbia through Washington and Oregon to Northern California. It includes both non-volcanic mountains, such as the North Cascades, ...

in the province of

British Columbia British Columbia (commonly abbreviated as BC) is the westernmost Provinces and territories of Canada, province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include ...

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tota ...

and the state of

Washington Washington commonly refers to: * Washington (state), United States * Washington, D.C., the capital of the United States ** A metonym for the federal government of the United States ** Washington metropolitan area, the metropolitan area centered o ...

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., federal district, five ma ...

Morphology

Larger in size than its '' C. madrensis'' and '' C. lateralis'' counterparts, ''C. saturatus'' has a vague russet color outlining its head and shoulders and running down the length of its body (at least 286 mm).

Distribution

''C. saturatus'' occurs in the northwestern United States, north of the Columbia River, south of the

Tulameen River The Tulameen River is a tributary of the Similkameen River in the Canadian province of British Columbia. The Tulameen River is part of the Columbia River drainage basin, being a tributary of the Similkameen River, which flows into the Okanagan ...

, and west of the

Similkameen River The Similkameen River runs through southern British Columbia, Canada, eventually discharging into the Okanagan River near Oroville, Washington, in the United States. Through the Okanagan River, it drains to the Columbia River. The river is said ...

. No fossils have yet been found. ''C. saturatus'' is isolated from its sister species ''S. lateralis'' by the Columbia River; their differentiation is likely due to

allopatric speciation Allopatric speciation () – also referred to as geographic speciation, vicariant speciation, or its earlier name the dumbbell model – is a mode of speciation that occurs when biological populations become geographically isolated from ...

Physiology

At birth, ''C. saturatus'' are

ectotherm An ectotherm (from the Greek () "outside" and () "heat") is an organism in which internal physiological sources of heat are of relatively small or of quite negligible importance in controlling body temperature.Davenport, John. Animal Life a ...

ic. Development of

endotherm An endotherm (from Greek ἔνδον ''endon'' "within" and θέρμη ''thermē'' "heat") is an organism that maintains its body at a metabolically favorable temperature, largely by the use of heat released by its internal bodily functions inste ...

y occurs gradually as individuals grow, increasing both body mass and amount of body fur. Individuals removed from their mother at 6 days of age lost body temperature at a faster rate than at 36 days, when individuals were able to maintain a high internal body temperature and determined to be homeothermic. This 36-day mark is conveniently the age at which offspring leave their burrows. Individuals remained homeothermic in response to a 2-day removal of food and water at 2-week intervals. Even with this drastically reduced body mass, torpor was not induced. Smaller individuals did become hypothermic, however, and were returned to the mother to be re-warmed. Daily energy expenditures showed a small but significant increase of 10% as litter size increased, across a range of 3 to 5 offspring, the norm for the species. Body mass, time spent above ground and time spent foraging were not correlated. For the large amount energy contained in the mother's milk, changes in metabolism were small. Body mass and age of offspring was independent of litter size. The fact that daily energy expenditure does not vary with litter size suggests that other factors, such as habitat quality, affect number of offspring. ''C. saturatus'' have been noted to move in two distinct ways – walking (mean speed of .21 m/s) and running (mean speed of 3.63 m/s). 26.9% of total time spent daily above ground was spent walking, while only 3.6% was spent running. It is noted that individuals run at their maximum aerobic speed of 3.6 m/s instead of the more maintainable minimum running pace of 2 m/s in order to minimize predation. ''C. saturatus'' moved an average of 5 km/day – 1.5 km walking and 3.3 km running. This considerable distance required 28.75 kJ/day of net added energy cost to do so, a 29% increase above BMR and 13% of daily energy expenditure.

Behavior

Examination of alarm calls in response to ''

Canis lupus familiaris The dog (''Canis familiaris'' or ''Canis lupus familiaris'') is a domesticated descendant of the wolf. Also called the domestic dog, it is derived from the extinct Pleistocene wolf, and the modern wolf is the dog's nearest living relative. D ...

'' among several species of ground squirrels showed that ''C. saturatus'' have a dialect of their own. Vocalizations were distinct, and could be identified 100% of the time by a discriminant source. This suggests that vocalizations can be used in addition to genetics and morphology to differentiate and designate species.

References

External links

* {{Authority control Callospermophilus Mammals described in 1895 Taxa named by Samuel Nicholson Rhoads Taxonomy articles created by Polbot