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 Mandible, lower jaws. About 40% of all mammal specie ...

in the family

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

, 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 Mandible, lower jaws. About 40% of all mammal specie ...

ia. It is the largest species of the three within the genus '' Callospermophilus.'' 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 many of those in the ...

in the province of

British Columbia British Columbia is the westernmost Provinces and territories of Canada, province of Canada. Situated in the Pacific Northwest between the Pacific Ocean and the Rocky Mountains, the province has a diverse geography, with rugged landscapes that ...

Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...

and the state of

Washington Washington most commonly refers to: * George Washington (1732–1799), the first president of the United States * Washington (state), a state in the Pacific Northwest of the United States * Washington, D.C., the capital of the United States ** A ...

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

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 The Columbia River (Upper Chinook language, Upper Chinook: ' or '; Sahaptin language, Sahaptin: ''Nch’i-Wàna'' or ''Nchi wana''; Sinixt dialect'' '') is the largest river in the Pacific Northwest region of North America. The river headwater ...

, south of the Tulameen River in

, and west of the Similkameen River. 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 (), more commonly referred to as a "cold-blooded animal", is an animal in which internal physiological sources of heat, such as blood, are of relatively small or of quite negligible importance in controlling body temperature.Dav ...

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 inst ...

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 gray wolf. Also called the domestic dog, it was selectively bred from a population of wolves during the Late Pleistocene by hunter-gatherers. ...

'' 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