161.

Savi’s Pine Vole

Microtus savii

French: Campagnol de Savi / German: | talien-Kleinw(ihimaus / Spanish: Topillo de Savi

Taxonomy. Arvicola savii de Sélys-LLongchamps, 1838, near Pisa, Italy.

Microtus savii is in subgenus Terricola and savii species group. It was only recently split into three allopatric species: savii, brachycercus, and nebrodensis . In the past, M. savii was classified in genus Pitymys . Monotypic.

Distribution. S Switzerland (E Valais and Ticino) and N & C Italy.

Descriptive notes. Head-body 83-100 mm, tail 24-30 mm; weight 16-5-24 g. Sexes are the same size. Savi’s Pine Vole is small, with short tail averaging ¢.26% of head-body length. Ears are short, but eyes are less reduced than in other pine voles. Females have two pairs of inguinal nipples. Skull and dental peculiarities are like in the Calabria Pine Vole (M. brachycercus).

Habitat. Pastures, meadows, gardens, vineyards, orchards, arable land, and various types of forests (deciduous, mixed, and coniferous) from lowlands up to elevations of ¢.2800 m.

Food and Feeding. Savi’s Pine Vole prefers grasses ( Poaceae), legumes ( Fabaceae), daisies ( Asteraceae), and goosefoot plants ( Amaranthaceae).

Breeding. Breeding season of Savi’s Pine Vole in Switzerland is in March—-November, but captive individuals can reproduce throughout the year. Gestation lasts 20-24 days (mean 20 days). Litters have 1-4 young; mean litter size (2-5) is same in free-living and captive individuals. Multiparous litters do not differ from primiparous ones. Captive females had 11-8 litters/year, and mean interpartum time was 29-4 days. Sexual maturity is reached at 50 days old for females and 47 days old for males. Mean age of first parturition in captive females is 72-6 days. In captivity, 41-5% of individuals survived 360 days and 20-8% survived 540 days.

Activity patterns. Activity rhythm is polyphasic and does not differ profoundly between seasons. Savi’s Pine Vole is active ¢.33% of the time. It is fossorial, moving through underground galleries of rectilinear corridors, with several exits to the ground’s surface. Tunnels are 10-50 cm underground. Savi’s Pine Voles frequently use galleries excavated by moles and modify them, particularly by connecting lateral tunnels with the surface. Excavated soil is pushed up to the surface and can be assembled in small heaps. Each network of tunnels contains several nests. Savi’s Pine Vole avoids moving abovegroud, and nearly all feeding is done within 10 cm of an entrance to a burrow.

Movements, Home range and Social organization. In Switzerland, home ranges averaged 445 m* for males and 298 m?* for females. Savi’s Pine Vole is characterized by a complex social structure. Territories are communal and exclusive, occupied by 1-3 adult females, one or more adult males, and several young. All family members share three or more communal nests. Mating system is flexible and includes monogamy, polygyny, and polyandry.

Status and Conservation. Classified as Least Concern on The IUCN Red List (together with the Sicilian Pine Vole, M. nebrodensis). Savi’s Pine Vole is abundant and separation from the Sicilian Pine Vole probably does not alterits conservation category.

Bibliography. Amori, Contoli & Nappi (2008), Caroli et al. (2000), Castiglia et al. (2008), Krapp (1982c), Salvioni (1988, 1995¢).