small+mammals

Broken up into three family groups that could potentially be used to increase model resolution without resorting to species level. Family groups presumably have similar responses in terms of population dynamics and response to habitat changes. toc = = =Leporidae= //Family containing rabbits and hares//


 * reproduces from March to September
 * 3.8 litters per year (average) in Wisconsin
 * Litter size varies according to location and number of previous litters produced (Murray 2003)
 * Populations in the boreal forest fluctuate according to a 10-year cycle, where their densities may vary 100-fold over the span of several years

Habitat

 * associated with mixed and boreal forest
 * stands 25-40 years old appear to be ideal
 * requires dense vegetation to use as cover

Diet
= =

=Muroidea= //Superfamily of Rodentia; contains mice, rats, voles, hamsters, and gerbils//

Demography

 * Populations appear to be limited by winter survival (Boonstra and Krebs 2006)
 * Debate whether populations are cyclical - don't appear to be (Boonstra and Krebs 2012)
 * Compilation of seasonal demographic rates available in Boonstra and Krebs (2012); incorporated into functions for R statistical language

Reproduction

 * Breeds late winter to late fall
 * Gestation is 17 to 19 days
 * weaned at 17 to 21 days
 * Sexual maturity at 3 months
 * 2 to 3 litters per year
 * 1 to 11 young per litter (avg 3 to 7)

Lifespan

 * up to 20 months
 * typically 12-18 months

Territory

 * Home range varies from 0.25 to 3.5 acres (Merritt and Merritt 1978)
 * Experimentation by Gillis and Nams (1998) suggests that populations separated by an inter-patch distance of 60-70 m would likely be isolated from one another
 * Mature females are territorial

Habitat

 * tend to be associated with forest habitat (Merritt 1981)
 * appears to increase in abundance as a result of clearcutting (Kirkland 1990)
 * increases seen when most forest types cut, including mixed deciduous, mixed deciduous/coniferous, Northern hardwoods (3/4 studies), especially oak
 * Oak forests typically too dry before cutting
 * cutting increases herbaceous vegetation and morning dew retention (important water source?)
 * decreases when clear cutting Northern hardwoods (1/4 studies) and aspen
 * reduction in numbers related to overstory removal in Western North America
 * Tend to utilize young clearcuts (0-5 yrs), but avoid older cuts (6-10 yrs) (Sekgororoane and Dilworth 1995)

Diet
Red-backed voles are opportunistic feeders and change their diet as the seasons progress. They eat leaf petioles and young shoots in the spring, add fruits and berries to their diet in the summer, and then switch to nuts and seeds in the autumn. They also consume some bark, roots, lichens, fungi, and insects. They sometimes store food in their nests for use in the winter when it becomes difficult to forage, although they continue to forage for seeds, tree roots, and bark under the snow.

Primary Diet:

 * **omnivorous**
 * **Animal Foods**: insects
 * **Plant Foods**: leaves; roots and tubers; wood, bark, or stems; seeds, grains, and nuts; fruit; flowers
 * **Other Foods**: fungus
 * **Foraging Behaviors**: stores or caches food

Models
A demographic model was written in R to simulate the dynamics of vole populations. Demographic parameters reflecting the seasonal population change (summer and winter) were obtained from a review paper which aggregated a number of study results (Boonstra and Krebs 2012). Parameters for a total of ten different study locations were supplied, and used to parameterize population projections using the model

math P_{t,spring} = P_{t-1,fall} * \Delta_{summer} math math P_{t,fall} = P_{t,spring} * \Delta_{spring} math



Datasources
Animal Diversity Web IUCN Red List Encyclopedia of Life