Common shrew

Sorex araneus

TAXONOMY

Sorex araneus Linnaeus, 1758, Uppsala, Sweden. The common shrew displays phenomenal chromosomal variation. About 70 karyotypic races have been described throughout the distribution range.

OTHER COMMON NAMES

French: Musaraigne commune; German: Waldspitzmaus; Spanish: Musaraña colicuadrada.

PHYSICAL CHARACTERISTICS

Head and body length 2.6-3.4 in (6.5-8.5 cm); tail 1.3-1.9 in (3.2-4.7 cm); weight 0.2-0.5 oz (5-14 g). Gray-brown fur with light underside. Feet are hairless.

DISTRIBUTION

Europe and Asia. The European range includes Great Britain and the Pyrenees, but the species is absent from Iberia, most of France, and Ireland. It extends eastwards as far as Lake Baikal.

HABITAT

It is the most abundant species of the European shrews, and it can be found everywhere in sites with enough humidity, soft soil layers, and some undergrowth. It occurs in a wide range of habitats including woodlands, grassland, hedgerows, heath, dunes, and scree. May live up to the limits of the summer snow line.

BEHAVIOR

Solitary and aggressive. It is active during day and night with about 10 periods of almost continuous activity. The common shrew makes its own surface runways through the ground vegetation, but it may also use the subterranean burrows of voles and moles.

FEEDING ECOLOGY AND DIET

It is an opportunistic feeder, preying on a wide range of insects, spiders, small mollusks, earthworms, and wood lice.

REPRODUCTIVE BIOLOGY

The female gives birth to the young from April to October, three or four times a year. The average litter size 5-7, a maximum of 11 young. Young disperse shortly after weaning and individuals of both sexes establish their own home range, varying in size from 0.09-0.16 acre (0.04-0.06 ha). Population densities are highly variable and may range from 17 to 110 individuals per acre (42-270 per ha) in summer, and from 2 to 11 individuals per acre (5-27 per ha) in winter. Probably promiscuous.

CONSERVATION STATUS

Not listed by the IUCN, but included in the Conservation Action Plan for the Eurasian Insectivores. The species is especially vulnerable during the juvenile period of dispersal. Because of the composition of its diet with a considerable proportion of earthworms, it very intensively accumulates heavy metals in polluted areas.

SIGNIFICANCE TO HUMANS

An important model species in evolutionary studies. ♦

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