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Columbian ground squirrel

Urocitellus columbianus

The Columbian ground squirrel , is a species of rodent common in certain regions of Canada and the northwestern United States. It is the second largest member of the genus ''Urocitellus'', which is part of the tribe Marmotini, along with marmots, chipmunks, prairie dogs, and other holarctic ground squirrels. They are stout, with short dense fur, which is characteristically tawny across the bridge of the nose. Social encounters often are initiated with kissing behavior and the most common activity above ground is standing at attention. Residing in mountainous terrain and high plains in northern latitudes, they hibernate most of the year in underground burrows, which may be used for many years. They are emaciated when emerging in the spring. These long periods of torpor earned the squirrels the moniker "Seven Sleepers", since the rests last around seven months. The Columbian ground squirrel came to the attention of the scientific community through writings produced by Lewis and Clark, while 21st century molecular genetics has more finely illuminated its ties with other close relatives.
Columbian Ground Squirrel I love squirrels. I could spend a whole day just hanging out with them, especially these vocal characters. Columbian Ground Squirrel (Urocitellus columbianus) sitting outside the den at Waterton Lakes National Park of Canada, Alberta, Canada. Alberta,Canada,Columbian Ground Squirrel,Columbian ground squirrel,Geotagged,Spring,Urocitellus columbianus,Waterton Lakes National Park of Canada

Appearance

The Columbian ground squirrel is one of the largest members of the genus, the largest being the Arctic ground squirrel. They have a relatively sturdy, robust build. They measure 325–410 mm in length overall, with a tail measuring 80–116 mm . The hind feet measure 47–57 mm and the ear 16–22.5 mm .

The hair is dense and relatively short. The facial fur is bronze across the bridge of the nose. The fur along the back, legs, and feet is a more cinnamon buff, with darker fur closer to the body. There is a pale beige to buff ring of fur around the eye. The neck fur is gray along the sides of the cheeks. The flanks may be light beige or gray. They have a darker tail, with darker underfur and some lighter beige markings above and dark to grayish white below. Molting occurs diffusely, without a clear line of delineation.


Two subspecies have been described, which vary in appearance. Compared with ''U. c. columbianus'', the population ''U. c. ruficaudus'' has a tail more rufous and less gray above. The sides of the face and throat are also more deeply rust shaded. The legs and feet are darker as well. The skull of ''U. c. ruficaudus'' is broader, with more robust zygomatic arches.

Several albino variants have been found. An albino squirrel was captured alive by a student near Pullman, Washington in 1932. It had been in an alfalfa field. The animal had white hair and pink eyes. A zoologist reported intentions to keep the animal alive to study genetic inheritance patterns. The following year, he reported finding three more young albinos in the same area. Around 30 years prior, two albino skins had been collected, also near Pullman. It was proposed that the recessive trait persisted in the locality, appearing at sporadic intervals.
Columbian Ground Squirrel Columbian Ground Squirrel (Urocitellus columbianus) in the grass looking around at Glacier National Park, British Columbia, Canada. British Columbia,Canada,Columbian Ground Squirrel,Columbian ground squirrel,Geotagged,Glacier National Park,Spring,Urocitellus columbianus

Distribution

The Columbia ground squirrel is found in western areas of North America. It occurs in the Rocky Mountains, from as far north as western Alberta and southeastern British Columbia. They are found in the western parts of Montana, through central Idaho and into northern and eastern reaches of Washington. They are also found along plains of eastern Washington. In Oregon, they occur in mountainous area in the east-central part of the state. They reside between 700–8,000 feet in elevation.

The known fossil record of the Columbia ground squirrel consists of specimens recovered from the Wasden fossil site in Bonneville County, Idaho. Fossils from this site date to the late Pleistocene . The site is located at 1,584 metres elevation. Fossils of small mammals deposited at this site are primarily attributed to owl predation.

The distribution of the Columbia ground squirrel in Oregon was assessed based on consideration of animals obtained in 71 localities. Over 98% were obtained in the Blue Mountains ecoregion, which includes the Wallowa and Blue Mountain ranges. The remaining squirrels came from the Owyheee Uplands.

Status

The IUCN lists the Columbia ground squirrel as a species of least concern. The reason for this listing is that the animal is widespread and common in its range and no major threats to the survival of the species are identified. Population trends are listed as stable. Similarly, the state of Montana, considers Columbian ground squirrels an important part of the state's ecosystem, noting that the animals are abundant with a wide spread distribution and are not vulnerable through most of their range.

Behavior

Columbian ground squirrels in Alberta hibernate around 250 days a year, with only 69–94 days of activity observed. The amount of time active varies depending on local climate as well as variations in behavior of animals of different sexes and ages. During hibernation, the squirrels are positioned vertically in a tight ball. The temperature drops significantly, the heart rate slows and respirations are scarcely perceptible. The first group to emerge are the adult males, followed by adult females, yearlings, then juveniles. Animals at higher elevations and latitudes emerge later. They emerge from hibernation and start breeding earlier at low elevations.

One brood per year will be raised. Young are born naked, blind, and toothless. After 5–6 days, their weight has doubled. They are covered with dark silky hair by day 12. Around day 17, the eyes are beginning to open. They may emerge into the sunlight outside the den around day 21-24. After 4 weeks, they are able to leave the nest altogether.

Mammalogist Vernon Orlando Bailey examined a Columbia ground squirrel burrow at an elevation of 7,000 ft near the Piegan Pass in Glacier National Park. In late July, a stout adult female was found bringing up fresh soil to the burrow entrance daily. The animal was removed and the burrow excavated for examination The mound at the entrance consisted of an estimated 8 US gal of soil. The soil was of varying dates of accumulation, since the lower layers appeared packed from previous seasons. The burrow itself had this main opening as well as two alternates, which were concealed from external observation and likely served as avenues of escape if a predator were to enter the burrow. The main shafts of the burrow were around 3.5 in in diameter. Chambers were established and varying intervals throughout the burrow, possibly to allow for storage of earth being excavated or safe haven from predators. At a distance of around 8 ft from the entrance, a nest had been constructed. The nest itself was made from leaves of locally abundant "glacier grass" . Varying ages of grass were found, suggesting that the nest had been used during prior seasons. In an adjoining chamber, deeper down in the earth, an older abandoned nest, filled partially with excrement, apparently served as a toilet for the squirrel.

The two types of burrow entrance were also noted by other observers, with one being small and roughly the same diameter as the tunnel itself, while another larger and more funnel shaped. The amount of soil excavated is around 4–12 kg per year, with an estimated 4–7 m of annual tunnel construction to established burrows. New burrow construction results in 25–50 kg of soil excavation.

The most common activities for Columbian ground squirrels, while above ground, include standing at attention, feeding, and grooming. More time was spent standing at attention than engaging in other activities. Aggressive behavior was observed most commonly in adult males, particularly early in the season. Columbian ground squirrel activity patterns are sensitive to climate and ambient light, avoiding cloudy days, cold winds, and inclement weather. They emerge from dens about an hour before sunrise and return near sunset. They are active during the hottest parts of the day, but more likely to be found out around mid-morning.

Columbian ground squirrels, when encountering each other, commonly will touch their mouths and noses together, an act resembling kissing. These greetings last 1–5 seconds and may precede other social interactions, including sexual activity.

C. Hart Merriam, writing in 1891, documented reports of the Columbian ground squirrel's behavior provided by local observers in Idaho. If disturbed while out of the burrow, the squirrels stood at attention, watching while approached to within a few yards, then raced for the burrow entrance, making squeaks and whistles. Locals called them "Seven sleepers", because they stayed underground for about seven months of the year. They were noted to have ample fat supplies when entering burrows to hibernate, but observed to be weak and thin when emerging the following spring. The mounds excavated by burrowing squirrels ranged from 3–10 inches in height. The burrows descended vertically from the entrance 18–24 inches .

Habitat

The Columbia ground squirrel is found in western areas of North America. It occurs in the Rocky Mountains, from as far north as western Alberta and southeastern British Columbia. They are found in the western parts of Montana, through central Idaho and into northern and eastern reaches of Washington. They are also found along plains of eastern Washington. In Oregon, they occur in mountainous area in the east-central part of the state. They reside between 700–8,000 feet in elevation.

The known fossil record of the Columbia ground squirrel consists of specimens recovered from the Wasden fossil site in Bonneville County, Idaho. Fossils from this site date to the late Pleistocene . The site is located at 1,584 metres elevation. Fossils of small mammals deposited at this site are primarily attributed to owl predation.

The distribution of the Columbia ground squirrel in Oregon was assessed based on consideration of animals obtained in 71 localities. Over 98% were obtained in the Blue Mountains ecoregion, which includes the Wallowa and Blue Mountain ranges. The remaining squirrels came from the Owyheee Uplands.

References:

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Status: Least concern
EX EW CR EN VU NT LC
Taxonomy
KingdomAnimalia
DivisionChordata
ClassMammalia
OrderRodentia
FamilySciuridae
GenusUrocitellus
SpeciesU. columbianus
Photographed in
Canada