Mammalogy Lab -- Quiz Three

Subfam Arvicolinae - skulls

Microtine molars (knife-like) with triangles of dentine surrounded by enamel; pronounced orbital process

Subfam Arvicolinae - natural history characteristics

• Altricial young

• Mostly breed in summer months

• Mostly active at night (but can be active during the day)

• Do not hibernate

• Small homeranges (15 m - 0.5 ha)

• Polyestrous (multiple estrous cycles within a year → can have multiple litters/year)

• Primarily herbivorous

Myodes gapperi (or Clethrionomys gapperi) - Southern red-backed vole

Family Cricetidae; subfam Arvicolinae

ID: Reddish stripe on dorsal pelage; bicolored tail; short tail relative to other voles

N. hist.

• Typically found in high-elevation, coniferous, and mixed forests

• In WY, usually found in lodgepole pine-dominated forests

• Diet: leaves, seeds, berries, insects, fungi (spreads spores)

• Active at dusk and night

Lemmiscus curtatus - Sagebrush vole

Family Cricetidae; subfam Arvicolinae

ID: Lighter gray or grayish-yellow pelage; short tail relative to other voles (same length as hind foot)

N. hist.

• Occur in sagebrush steppe

• Diet: grasses and leaves in the summer; sagebrush bark and twigs in the winter

• Colonial species (but not monogamous) with no paternal care → pups live with parents even after new litters are born

• Active at any time during day/night

Microtus longicaudus - Long-tailed vole

Family Cricetidae; subfam Arvicolinae

ID: Brownish-gray pelage; lighter ventral pelage; long, bicolored tail (33-50% of body length)

N. hist.

• Found in wider variety of habitats (more generalist) → dry grassy areas, mountain slopes, stream banks → more likely to be found closer to water

• Diet: plants and fungi (no mutualism, though)

• No well-defined runways (unlike other voles)

• Active day and night

• First successional species of wildfires → benefit immediately post-fire

Microtus montanus → Montane vole

Family Cricetidae; subfam Arvicolinae

ID: Brown dorsal pelage; ventral pelage off-white to grey; bicolored tail

N. hist.

• Occur in mountainous herbaceous meadows (below treeline) → specialist

• Strictly herbivorous

• Known as pests in agricultural settings

Microtus ochrogaster - prairie vole

Family Cricetidae; subfam Arvicolinae

ID: Grayish-brown dorsal pelage; orange/yellow wash on belly; guard hairs can give a grizzled appearance; tail of intermediate length (10-25% of body length)

N. hist.

• Typically occur in mesic (moderate amt. of moisture) grasslands and sagebrush-grass communities

• Herbivorous, but diverse diet

• Monogamous with social systems (if a mate dies, the other might not mate again)

  • Pups disperse from area; if they stay, they won’t be fertile (prevents inbreeding)

• Little to no sexual dimorphism

• Most active at dusk and night

Microtus pennsylvanicus - meadow vole

Family Cricetidae; subfam Arvicolinae

ID: Brownish-gray dorsal pelage; gray ventral pelage; tail is short relative to M. longicaudus

N. hist.

• Generalist → meadows, riparian shrubs and woodlands, forest edges

• In N WY, found at high elevations

• Strictly herbivorous

• Active day and night

Ondatra zibethicus - Muskrat

Family Cricetidae; subfam Arvicolinae

ID: Largest skull in WY exhibiting microtine teeth; chocolate brown dorsum; two coats (thick undercoat and outer guard hairs); tail is laterally flattened and nearly hairless; partially-webbed hindfeet with lots of hairs; excrete musk for communication

N. hist.

• Semi-aquatic (freshwater streams and ponds)

• Diet: mainly aquatic vegetation, but, occasionally, clams, crayfish, frogs, small turtles (and cannabalism)

• Crepuscular to nocturnal

• Stick within 15 m of nest (young disperse)

• Larger hindfoot than front