Mammalogy Lab -- Quiz Four

Family Sciuridae - skulls

Post-orbital processes conspicuous and obvious; number of cheek teeth helps ID species (premolars and molars; typically 4-5)

Three tribes of Sciurids in Wyoming

Sciurini - Tree squirrels

Pteromyini - flying squirrels

Marmotini - ground squirrels

Cynomys leucurus - White-tailed prairie dog

Family Sciuridae

ID

• Yellowish pelage

• Relatively short, white tail

• Black eyebrows

Nat. hist.

• Steppe specialist (sagebrush)

• Diurnal

• Hibernate → plug up burrows to protect from disturbance

• Occurs in colonies smaller than C. ludovicianus (less social)

• Least imperiled

• Reproduce at one year; larger litters

• Monoestrous → 1 litter/year; gestation = 30 days; wean at 35 days; litter size = 5-6 pups; lifespan = up to 6 years

Cynomys ludovicianus - Black-tailed prairie dog

Family Sciuridae

ID

• Yellowish pelage

• Relatively long, black tail

• No eyebrows!!

Nat. hist.

• Shortgrass prairie specialist

• Facultative hibernator (in response to env. conditions); eat cactus and thistle in the winter

• Within colonies, social structure based on coteries (neighborhood; not necessarily relatives)

• 98% range collapse from 1900-2000; 5 bill. - 18.4 mill (0.05% of hist. numbers)

• Susceptible to plague → 90% of colony can collapse from one infected individual

• Reproduce at two years; smaller litters

• Monoestrous → gestation = 30-35 days; wean at 45 days; 4-5 pups; lifespan = 5 years

Marmota flaviventris - Yellow-bellied marmot

Family Sciuridae

ID

• Grizzled dorsal pelage with yellow-brown ventral pelage; sides of the neck bright yellow

• Lots of melanism in the Tetons!

N. hist.

• Eats grasses, forbs, and seeds

• Hibernates 8-9 months/year

• Often found on rock slides or talus (high elevations)

• Social

• Monoestrous → won’t always breed two years in a row; gestation = 30 days; wean at 26 days; 4 pups; lifespan = up to 20 years

Urocitellus armatus - Uinta ground squirrel

Family Sciuridae

ID

• Grayish-brown pelage with some yellow on body

• Tail is blackish

N. hist.

• Omnivorous

• Note small geographic range

• Diurnal

• Occurs in open areas in mountain meadows and forest edges

• Eats grasses, forbs, and seeds

• Hibernates

• Monoestrous → gestation = 24 days; wean at 21 days; 5 pups; lifespan = 5 years

Urocitellus elegans - Wyoming ground squirrel

Family Sciuridae

ID

• Grayish pelage typically without yellow

• Tail is not black

• Smaller than Uinta

N. hist.

• Omnivorous

• Diurnal

• Females live in colonies; males are mostly solitary

• Occur in well-drained shortgrass prairie and sagebrush steppe

• Considered a pest

• Might hybridize with Uinta

• Monoestrous → gestation = 23 days; wean at 32 days; 6 pups; lifespan = 6 years

Callospermophilus lateralis - Golden-mantled ground squirrel

Family Sciuridae

ID

• Large chipmunk; stripes do not extend to eyes

• White eye ring

N. hist.

• Omnivorous (fungi, seeds, acorns)

• Occurs in mountain meadows and forest edges

• Diurnal

• Hibernates

• Asocial

• Monoestrous → gestation = 28 days; wean at 39 days; 5 pups; lifespan = 2-3 years

Ictidomys tridecemlineatus - Thirteen-lined ground squirrel

Family Sciuridae

ID

• 13 rows of alternating stripes and spots on dorsum

• Pelage yellow and black

• Yellow eye ring

N. hist.

• Omnivorous

• Hibernates; up to 90% of offspring die before they can

• Solitary

• Avoids wooded areas; prefers open shortgrass

• Mostly monoestrous → gestation = 27 days; wean at 28; 6-9 pups; lifespan = 8 years

• Trills!!

Eutamias minimus - Least chipmunk

Family Sciuridae

ID

• Stark black and white stripes that extend onto the face

• Smaller; proportionally longer tail

N. hist

• Omnivorous → bird eggs, mammals, seeds, fruits, fungi; important seed dispersers

• Hibernate → torpor; must wake up to eat every 5-7 days

• Smallest and most widely-distributed chipmunk

• Monoestrous → wean at 1 month; 4-6 pups; lifespan = 9 years

Eutamias amoenus - Yellow-pine chipmunk

Family Sciuridae

ID

• Stark black and white stripes that extend onto the face

N. hist

• Omnivorous → bird eggs, mammals, seeds, fruits, fungi; important seed dispersers

• Hibernate → torpor; must wake up to eat every 5-7 days

• Monoestrous → wean at 1 month; 4-6 pups; lifespan = 5 years

Glaucomys sabrinus - Northern flying squirrel

Family Sciuridae

ID

• Thick, gray pelage

• Patagium extends between wrists and ankles

• Well-furred, dorso-ventrally flattened tail

N. hist.

• Over 20 subspecies!

• Strictly nocturnal; active year-round

• Forest-dwelling

• Share nusts and huddle in the winter

• Can glide between 5 and 25 meters

• Eats fungus (mycophagous)

• Monoestrous → gestation = 40 days; wean at 66 days (maiden flight!); 3 pups; lifespan = 13 years

• Longest limbs of all squirrels

• Upturned wing tip (for stability)

Tamiasciurus hudsonicus - North American red squirrel (or pine squirrel)

Family Sciuridae

ID

• Bicolored pelage → white ventral and reddish dorsum

• White eye ring

• Tufted ears

N. hist.

• Occurs in coniferous forests

• Larder-hoarder → caches food altogether in a central location

• Eats conifer seeds

Sciurus aberti - Abert’s squirrel

Family Sciuridae

ID

• Typically dark gray, but can be melanistic (mostly melanistic in WY)

• Large ear tufts

N. hist.

• Obligate to ponderosa pine forests

• Northern limit is the Laramie Mt. range

• Do not make caches

Sciurus niger - Eastern fox squirrel

Family Sciuridae

ID

• Orange pelage typically, but variable!

• Bushy, fox-like, “animated” tail

N. hist.

• Granivorous scatter-hoarder (caches food in several places)

• Small game species

• WY populations → combination of range expansion and introduction to CO

• Polyestrous → gestation = 44 days; wean at 76 days; 5-6 pups; probably 2-3 litters/year; lifespan = up to 12 years

• Skulls can glow under UV (urine doesn’t get metabolized properly and gets stored in the bones)