Savi's pine vole (''Microtus savii'') is a species of

rodent Rodents (from Latin , 'to gnaw') are mammals of the Order (biology), order Rodentia ( ), which are characterized by a single pair of continuously growing incisors in each of the upper and Mandible, lower jaws. About 40% of all mammal specie ...

in the family

Cricetidae The Cricetidae are a family of rodents in the large and complex superfamily Muroidea. It includes true hamsters, voles, lemmings, muskrats, and New World rats and mice. At over 870 species, it is either the largest or second-largest family ...

, widespread across the Italian peninsula with limited populations in southern France and southern Switzerland. This herbivorous mammal primarily inhabits agroecosystems, including rural areas,

orchard An orchard is an intentional plantation of trees or shrubs that is maintained for food production. Orchards comprise fruit tree, fruit- or nut (fruit), nut-producing trees that are generally grown for commercial production. Orchards are also so ...

meadow A meadow ( ) is an open habitat or field, vegetated by grasses, herbs, and other non- woody plants. Trees or shrubs may sparsely populate meadows, as long as they maintain an open character. Meadows can occur naturally under favourable con ...

s, and agricultural fields, constructing complex

burrow file:Chipmunk-burrow (exits).jpg, An eastern chipmunk at the entrance of its burrow A burrow is a hole or tunnel excavated into the ground by an animal to construct a space suitable for habitation or temporary refuge, or as a byproduct of Animal lo ...

systems about 40–50 cm deep. Although its taxonomy remains debated, with proposed

subspecies In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...

and recent genetic studies suggesting significant

divergence In vector calculus, divergence is a vector operator that operates on a vector field, producing a scalar field giving the rate that the vector field alters the volume in an infinitesimal neighborhood of each point. (In 2D this "volume" refers to ...

between populations, it is recognized as a distinct species from the closely related '' Microtus brachycercus''. Savi's pine vole is known for its ecological impact on agriculture, causing substantial damage to vegetable crops and fruit trees through root consumption and trunk debarking, while serving as a prey species for various predators including owls, kestrels, weasels, and foxes.

Taxonomy and morphology

The

taxonomy image:Hierarchical clustering diagram.png, 280px, Generalized scheme of taxonomy Taxonomy is a practice and science concerned with classification or categorization. Typically, there are two parts to it: the development of an underlying scheme o ...

of Savi's pine vole remains debated. Several

have been proposed, including ''M. s. savii'' in northern and central Italy, ''M. s. brachycercus'' in southern Italy, and ''M. s. nebrodensis'' in Sicily. Recent genetic studies suggest significant

between northern-central and southern populations, possibly indicating the early stages of

speciation Speciation is the evolutionary process by which populations evolve to become distinct species. The biologist Orator F. Cook coined the term in 1906 for cladogenesis, the splitting of lineages, as opposed to anagenesis, phyletic evolution within ...

. '' Microtus brachycercus'', initially considered a subspecies, has been validated as a distinct species based on genetic and karyological data. Genetic analyses indicate possible areas of

sympatry In biology, two closely related species or populations are considered sympatric when they exist in the same geographic area and thus frequently encounter each other. An initially interbreeding population that splits into two or more distinct spe ...

or hybridisation zones between ''Microtus savii'' and ''Microtus brachycercus'' in central Italy, particularly around

Umbria Umbria ( ; ) is a Regions of Italy, region of central Italy. It includes Lake Trasimeno and Cascata delle Marmore, Marmore Falls, and is crossed by the Tiber. It is the only landlocked region on the Italian Peninsula, Apennine Peninsula. The re ...

. The

morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines *Morphology (archaeology), study of the shapes or forms of artifacts *Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies, ...

, particularly tooth patterns, varies geographically. Climatic factors appear to influence regional morphological differences, while local population isolation contributes to distinct morphotypes. Dental morphology, especially the anterior loop of the first lower molar (m1), is commonly used to distinguish ''Microtus savii'' from ''Microtus brachycercus''. Typically, ''M. brachycercus'' shows a more open anterior loop compared to ''M. savii'', although substantial morphological variability complicates identification based solely on dental features.

Distribution and habitat

Savi's pine vole is widely distributed in Italy, with small populations in southern France and the southern Canton Ticino in Switzerland. In Italy, its distribution reaches altitudes up to 2,800 meters. It is common in rural areas, orchards, meadows, agricultural fields, and occasionally urban environments, preferring deep, moist, and well-drained soils. It avoids rocky and excessively dry terrains. This vole constructs complex

systems approximately 40–50 cm deep, often repurposing mole tunnels. Their home range varies from 300 m² for females to 450 m² for males. Colony sizes can reach up to 15 closely related individuals sharing nests.

Ecology

Savi's pine vole has a strictly herbivorous diet, predominantly consuming grasses, roots, and occasionally bark, particularly in winter when herbaceous vegetation is scarce. It has a polyphasic daily activity rhythm, alternating between short rest and activity periods throughout the day and night. The main

predators Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill ...

of Savi's pine vole include

barn owl The barn owls, owls in the genus '' Tyto'', are the most widely distributed genus of owls in the world. They are medium-sized owls with large heads and characteristic heart-shaped faces. They have long, strong legs with powerful talons. The ter ...

s (''Tyto alba''),

tawny owl The tawny owl (''Strix aluco''), also called the brown owl, is a stocky, medium-sized owl in the family Strigidae. It is commonly found in woodlands across Europe, as well as western Siberia, and has seven recognized subspecies. The tawny owl' ...

s (''Strix aluco''),

kestrel The term kestrel (from , derivative from , i.e. ratchet) is the common name given to several species of predatory birds from the falcon genus ''Falco''. Kestrels are most easily distinguished by their typical hunting behaviour which is to hover ...

s (''Falco tinnunculus''),

common buzzard The common buzzard (''Buteo buteo'') is a medium-to-large bird of prey which has a large range. It is a member of the genus '' Buteo'' in the family Accipitridae. The species lives in most of Europe and extends its breeding range across much of ...

s (''Buteo buteo''),

weasel Weasels are mammals of the genus ''Mustela'' of the family Mustelidae. The genus ''Mustela'' includes the least weasels, polecats, stoats, ferrets, and European mink. Members of this genus are small, active predators, with long and slend ...

s (''Mustela nivalis''), and

red fox The red fox (''Vulpes vulpes'') is the largest of the true foxes and one of the most widely distributed members of the order Carnivora, being present across the entire Northern Hemisphere including most of North America, Europe and Asia, plus ...

es (''Vulpes vulpes''). Barn owls are especially significant predators, potentially providing biological control.

Reproduction and population dynamics

The breeding season extends from March to November, with peaks in spring and summer. Females reach

sexual maturity Sexual maturity is the capability of an organism to reproduce. In humans, it is related to both puberty and adulthood. ''Puberty'' is the biological process of sexual maturation, while ''adulthood'', the condition of being socially recognized ...

around 50 days and have a

gestation Gestation is the period of development during the carrying of an embryo, and later fetus, inside viviparous animals (the embryo develops within the parent). It is typical for mammals, but also occurs for some non-mammals. Mammals during pregn ...

period of 22–24 days. The average

litter Litter consists of waste products that have been discarded incorrectly, without consent, at an unsuitable location. The waste is objects, often man-made, such as aluminum cans, paper cups, food wrappers, cardboard boxes or plastic bottles, but ...

size is about 2.5 offspring, and females may produce multiple litters annually. Under favourable laboratory conditions, Savi's pine voles have demonstrated the potential to breed continuously throughout the year, though they typically reproduce more frequently during wetter periods such as spring and winter. Females can produce approximately 12 litters per year in optimal conditions. Young voles have high survival rates, with about 99% surviving their first 20 days and over 70% living up to around 240 days. Females generally have their first litter at about 73 days of age, and litter sizes range from one to four offspring. Although smaller litters typically result in heavier juveniles, litter size tends to decrease slightly after reaching a peak as parents age. Population dynamics of Savi's pine vole differ from other ''Microtus'' species, as they do not show significant cyclical outbreaks. However, seasonal peaks in population density can occur, typically ranging from fewer than 50 individuals per hectare in summer to over 100 individuals per hectare in spring. The life-history traits of this species, including small litter sizes, delayed puberty, and relatively long gestation periods, characterise it as a more K-selected species compared to other voles, which typically exhibit rapid reproduction and large litter sizes.

Impact on agriculture

Savi's pine vole causes substantial agricultural damage, especially to vegetable crops and fruit trees. Damage includes root and trunk debarking, tunneling damage, and severe attacks on horticultural species such as artichokes, lettuce, cabbage, onions, and orchard trees, notably apple and citrus trees. Population increases and damage are associated with modern agricultural practices, such as maintaining permanent grass cover and

drip irrigation Drip irrigation or trickle irrigation is a type of micro-irrigation system that has the potential to save water and nutrients by allowing water to drip slowly to the roots of plants, either from above the soil surface or buried below the surfac ...

, which provide favourable conditions for voles year-round. Control strategies traditionally included

trapping Animal trapping, or simply trapping or ginning, is the use of a device to remotely catch and often kill an animal. Animals may be trapped for a variety of purposes, including for meat, fur trade, fur/feathers, sport hunting, pest control, and w ...

and

rodenticide Rodenticides are chemicals made and sold for the purpose of killing rodents. While commonly referred to as "rat poison", rodenticides are also used to kill mice, woodchucks, chipmunks, porcupines, nutria, beavers, and voles. Some rodenticides ...

s, with chlorophacinone previously being widely used. However, the use of rodenticides is now strictly regulated, encouraging integrated management strategies combining habitat modification, trapping, and

biological control Biological control or biocontrol is a method of controlling pests, whether pest animals such as insects and mites, weeds, or pathogens affecting animals or plants by using other organisms. It relies on predation, parasitism, herbivory, or o ...

s, such as promoting natural predators.

References

*Musser, G. G. and M. D. Carleton. 2005. Superfamily Muroidea. pp. 894–1531 ''in'' Mammal Species of the World a Taxonomic and Geographic Reference. D. E. Wilson and D. M. Reeder eds. Johns Hopkins University Press, Baltimore. {{Taxonbar, from=Q1764152 Microtus Mammals described in 1838 Taxonomy articles created by Polbot Taxa named by Edmond de Sélys Longchamps Fauna of Italy Fauna of Switzerland