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Sorex minutusEurasian pygmy shrew

By Serenity Mutchler

Geographic Range

Sorex minutus, more commonly known as the Eurasian pygmy shrew, is a small mammal that is native to the Palearctic region. It is the most widespread Eurasian shrew, and is found in northern Iberia and the British Isles as well as continental Europe, European Russia and Siberia. Although commonly found throughout Eurasia, S. minutus is absent from many islands, including the Shetland Isles, the Channel Isles, the Isles of Scilly and some of the smaller islands in the Stockholm archipelago.

Rangemap of Sorex minutus ("Arkive", 2010; "The Mammal Society", 2010; Hutterer, et al., 2008; Malmquist, 1985; Step, 1921; "Nature Online", 2008)

Habitat

Sorex minutus is a terrestrial mammal, preferring to live in areas with dense vegetation, which serve as protective cover. Since such conditions are easily met in many plant community types, S. minutus can be found in forests (boreal, temperate, and montane), woodland edge, shrubland (boreal and temperate), heathland, grasslands (temperate), wetlands (bogs, marshes, swamps, fens, peatlands), coastal sand dunes, and rocky areas. Though not natural, due to the dense ground cover, S. minutus also thrives in pastureland and hedgerows. It can also be found across a wide range of elevations, from sea level to 2260 m. ("Arkive", 2010; Hutterer, et al., 2008; Malmquist, 1985; Pernetta, 1976; Step, 1921; "Nature Online", 2008)

  • Range elevation
    0 to 2,260 m
    0.00 to ft

Physical Description

The coat of Sorex minutus is sleek, short, and dense with dorsal coloration ranging from grey-brown to brown and ventral coloration that is grayish-white. Occasionally, individuals have white tipped tails, and although rare, albinism occurs as well. It moults both in autumn (August to November, from tail to snout) and in spring (March to June, from snout to tail). ("Arkive", 2010; East, 1974; Rychlik and Jancewicz, 2002; Step, 1921; "Nature Online", 2008)

As with other Sorex species, the teeth of Sorex minutus are red, which is due to the deposition of iron that helps protect the teeth against wear. It has an extremely high metabolic rate (9.62 cm^3 oxygen/hour), which is typical of Sorex species as well. ("Arkive", 2010; "The Mammal Society", 2010; Rychlik and Jancewicz, 2002; Step, 1921; "Nature Online", 2008)

Sorex minutus is the smallest native British shrew. Adult body length ranges from 39 to 60 mm, tail length ranges from 32 to 46 mm, and adult weight ranges from 2.4 to 6.1 g (decreasing by 28% in the winter). It can easily be confused with the Eurasian shrew (Sorex araneus), but can be distinguished by its slightly paler coat color and a distinctly bi-colored tail that is longer and hairier than that of the Eurasian shrew. Sorex minutus has small eyes and short, rounded ears and complex lobes in the ear conch. The snout is narrow, long, and slender (i.e., pointed) with large whiskers at the end. It has short legs and plantigrade posture. Each foot has five digits, and the length of the hindfeet measures from 10 to 11 mm. Sexual dimorphism in S. minutus is minimal, with adult females having three pairs of visible teat spots and adult males having visible testicles. Both males and females have scent glands located on the flanks. ("Arkive", 2010; "The Mammal Society", 2010; Rychlik and Jancewicz, 2002; Step, 1921; "Nature Online", 2008)

  • Sexual Dimorphism
  • sexes alike
  • Range mass
    2.4 to 6.1 g
    0.08 to 0.21 oz
  • Average mass
    3.0 ± 0.13 g
    oz
  • Range length
    71 to 106 mm
    2.80 to 4.17 in
  • Average basal metabolic rate
    9.62 cm3.O2/g/hr

Reproduction

Little is known about mating in Sorex minutus. However, males expand their territories in search of females during breeding season. ("The Mammal Society", 2010)

Sorex minutus breeds from April to August (peaking in June) with a 19 to 25 day gestation period. Females either use abandoned nests made by other species or weave their own from dry grass. Females have two litters each season but can sometimes have as many as five. Lactation lasts for 22 to 30 days after birth and can sometimes cause anestrus (a period of sexual inactivity between breeding periods), causing a short break to occur between litters. Each litter consists of 4 to 12 altricial young, weighing 0.25 g on average, that are blind, naked, and toothless upon birth. Young often overwinter as immature pups and reach sexual maturity during their first spring; however, females born early in the year can mature prior to winter. ("Arkive", 2010; "The Mammal Society", 2010; Step, 1921; "Nature Online", 2008)

  • Breeding interval
    Sorex minutus usually breeds twice per season, but have been recorded breeding up to five times per season.
  • Breeding season
    Mating occurs from April to August.
  • Range number of offspring
    4 to 12
  • Average number of offspring
    7
  • Range gestation period
    19 to 25 days

Little is known about parental investment in Sorex minutus; however, young are born essentially defenseless (blind, naked, and toothless). Lactation lasts for 22 to 30 days after birth and females are thought to provide most of the care. ("The Mammal Society", 2010; Step, 1921)

  • Parental Investment
  • altricial
  • female parental care
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female

Lifespan/Longevity

Sorex minutus is able to survive up to 16 months in captivity and anywhere from 1.5 to 2 years in the wild. Peak mortality occurs in the first 2 to 4 months of life, which is when the young are naïve to predators and are learning which insects are edible. ("Arkive", 2010; "The Mammal Society", 2010)

  • Typical lifespan
    Status: wild
    1.5 to 2 years
  • Typical lifespan
    Status: captivity
    16 (high) months

Behavior

Sorex minutus is solitary. After establishing a territory, they readily defend it against both con- and heterospecifics. Population densities are highest during autumn and appear to decline with the availability of arthropods during winter. ("Arkive", 2010; "The Mammal Society", 2010; Malmquist, 1985)

Like other soricines, Sorex minutus has an extremely high metabolism, requiring it to consume approximately 125% its own bodyweight in insects each day. Though its activity levels heighten during dawn and dusk (indicating a crepuscular rhythm), its high energy demands result in an ultradian rhythm (recurrent periods or cycles repeating throughout a 24-hour photoperiod). Its high metabolic rate does not allow for the fat deposition required for hibernation, as any stored fat is used for thermogenesis (the creation of body heat). As a result, S. minutus remains active throughout the winter, spending up to 50% of its time foraging for food. It remains aboveground all winter, though it uses abandoned holes dug by other species for shelter when necessary. When snow is present, shrews use the subnivean zone (a region of open space located between the surface of teh groun and above the snow layer) while foraging. When snow is absent, they make tunnels in the ground cover. ("Arkive", 2010; "The Mammal Society", 2010; Malmquist, 1985; Pernetta, 1976; Rychlik and Jancewicz, 2002)

  • Range territory size
    530 to 1800 m^2

Home Range

Sorex minutus is a territorial mammal. Ranges vary in size from 530 to 1800 m^2 and sometimes decrease in size during the winter. Once ranges are established, they are exclusive to the resident individual. Territorial boundaries are marked using scent glands located on the flanks. Boundaries may change during mating season, as males may expand their territory to help them find potential mates. Sorex minutus exhibits high levels of aggression when boundaries are threatened by conspecifics. ("Arkive", 2010; "The Mammal Society", 2010; Malmquist, 1985; Pernetta, 1976; "Nature Online", 2008)

Sorex minutus exhibits higher levels of aggression when confronted by a sympatric and closely related species than when confronted by an allopatric and unrelated species. In addition, Rychlik and Zwolak (2006) showed that when territorial boundaries were crossed by other species, S. minutus became immediately defensive and remained so longer than any of the four Sorex species studied. When S. minutus initiated aggressive behavior towards a trespasser, it had the shortest attack time of the four species studied. ("Arkive", 2010; "The Mammal Society", 2010; Malmquist, 1985; Rychlik and Zwolak, 2006)

Communication and Perception

Eurasian shrews communicate via chemical cues as well as vocally. Territories are demarcated via scent markings. It has been suggested that S. minutus uses high-frequency echolocation to locate conspecifics or individuals that are trespassing in its territory. ("Arkive", 2010; Pernetta, 1976; "Nature Online", 2008)

Food Habits

Sorex minutus is an insectivorous mammal, eating both insects and other terrestrial arthropods (spiders, mites, scorpions, isopods, etc.). It is an opportunistic predator, using ultrasound as a primitive form of echolocation to help it locate food up to 12 cm deep in soil. It also hunts by probing into soil with its snout, smelling and feeling for potential prey. When a prey item is located, S. minutus attacks the head first to immobilize it and avoids the unpalatable parts (legs, large wings, etc.) while eating. ("Arkive", 2010; "The Mammal Society", 2010; Malmquist, 1985; Pernetta, 1976; Rychlik and Jancewicz, 2002)

The diet of Sorex minutus depends on the availability of prey, which can be affected by seasonality, weather, and habitat. With the possible exception of some millipede species, it is a non-specific insectivore and readily consumes most arthropods. Its diet consists of prey that are less than 6 mm long, including beetles (Coleoptera), woodlice, adult flies, insect larvae (e.g., winter moth, Operophtera brumata), and spiders (Nemastomatoidea spp. and Linyphiidae spp.). It has also been known to eat small slugs and snails, and small amounts of plant material, none of which are preferred food items. ("Arkive", 2010; "The Mammal Society", 2010; East, 1974; Pernetta, 1976; "Nature Online", 2008)

Studies show direct resource competition between Sorex minutus and Sorex araneus (Eurasian shrew) where they occur sympatrically. However, to decrease the degree of competition, both participate in resource partitioning. Sorex minutus is a non-burrowing mammal and has more difficulty obtaining insect larvae. Sorex araneus is a burrowing mammal and therefore, has a much easier time accessing insect larvae and earthworms. In addition, both species forage on prey that is similar in size to themselves, with S. araneus feeding on larger prey than S. minutus. However, S. minutus may cache larger prey items when there is an overabundance of food, as their metabolic requirements are too great to go without food for longer than a few hours (Malmquist, 1985; Pernetta, 1976; Rychlik and Jancewicz, 2002)

  • Animal Foods
  • insects
  • terrestrial non-insect arthropods
  • mollusks
  • terrestrial worms

Predation

The scent glands of Sorex minutus may serve as a deterrent to some predators. The major predators of S. minutus are tawny owls (Strix aluco), barn owls (Tyco alba), raptors, stoats and weasels (Mustelidae), foxes (Canidae), and domestic cats (Felis catus). ("Arkive", 2010; "The Mammal Society", 2010)

Ecosystem Roles

As an insectivore, Sorex minutus may help control insect populations, and East (1974) noted that predation on winter moth larvae (Operophtera brumata) had a significant impact on their abundance. Because they are prey for many species, S. minutus may help support small carnivore populations throughout Eurasia. Finally, Sorex species are extremely vulnerable to environmental changes. As a result, they are good biological indicators of environmental change (e.g., habitat destruction, heavy metal pollution, pesticide pollution, and climate change). ("Arkive", 2010; "The Mammal Society", 2010; East, 1974; Hutterer, et al., 2008; Malmquist, 1985; Pernetta, 1976; "Nature Online", 2008)

Economic Importance for Humans: Positive

Sorex minutus is an insectivore and requires large numbers insects due to its high metabolism. Thus, S. minutus may help control local insect populations, some of which may be significant agricultural pests. This species is also a good indicator of environment change. ("Arkive", 2010; "The Mammal Society", 2010; East, 1974)

  • Positive Impacts
  • controls pest population

Economic Importance for Humans: Negative

There are no known adverse effects of Sorex minutus on humans.

Conservation Status

Sorex minutus is abundant throughout its range and is listed as a species of "least concern" on the IUCN Red List of Threatened Species.

Contributors

Serenity Mutchler (author), University of Wisconsin-Stevens Point, Stefanie Stainton (editor), University of Wisconsin-Stevens Point, Christopher Yahnke (editor), University of Wisconsin-Stevens Point, John Berini (editor), Animal Diversity Web Staff.

Glossary

Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

World Map

acoustic

uses sound to communicate

agricultural

living in landscapes dominated by human agriculture.

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

bog

a wetland area rich in accumulated plant material and with acidic soils surrounding a body of open water. Bogs have a flora dominated by sedges, heaths, and sphagnum.

carnivore

an animal that mainly eats meat

chaparral

Found in coastal areas between 30 and 40 degrees latitude, in areas with a Mediterranean climate. Vegetation is dominated by stands of dense, spiny shrubs with tough (hard or waxy) evergreen leaves. May be maintained by periodic fire. In South America it includes the scrub ecotone between forest and paramo.

chemical

uses smells or other chemicals to communicate

coastal

the nearshore aquatic habitats near a coast, or shoreline.

crepuscular

active at dawn and dusk

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

detritus

particles of organic material from dead and decomposing organisms. Detritus is the result of the activity of decomposers (organisms that decompose organic material).

diurnal
  1. active during the day, 2. lasting for one day.
echolocation

The process by which an animal locates itself with respect to other animals and objects by emitting sound waves and sensing the pattern of the reflected sound waves.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

female parental care

parental care is carried out by females

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

insectivore

An animal that eats mainly insects or spiders.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

marsh

marshes are wetland areas often dominated by grasses and reeds.

motile

having the capacity to move from one place to another.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

polygynous

having more than one female as a mate at one time

scent marks

communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

stores or caches food

places a food item in a special place to be eaten later. Also called "hoarding"

swamp

a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.

tactile

uses touch to communicate

taiga

Coniferous or boreal forest, located in a band across northern North America, Europe, and Asia. This terrestrial biome also occurs at high elevations. Long, cold winters and short, wet summers. Few species of trees are present; these are primarily conifers that grow in dense stands with little undergrowth. Some deciduous trees also may be present.

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

ultrasound

uses sound above the range of human hearing for either navigation or communication or both

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

2010. "Arkive" (On-line). Pygmy shrew (Sorex minutus). Accessed August 02, 2010 at http://www.arkive.org/pygmy-shrew/sorex-minutus/info.html.

The Natural History Museum, London. 2008. "Nature Online" (On-line). Pygmy Shrew (Sorex minutus). Accessed August 02, 2010 at http://www.nhm.ac.uk/fff-pcp/glob.pl?report=Fauna&Fauna.[FaunaNo]=1359.

2010. "The Mammal Society" (On-line). Sorex minutus - Eurasian pygmy shrew. Accessed August 02, 2010 at http://wildlife1.wildlifeinformation.org/s/0MInsectivor/Soricidae/Sorex/Sorex_minutus/Sorex_minutus.html.

East, R. 1974. Predation on the Soil-Dwelling Stages of the Winter Moth at Wytham Woods, Berkshire. Journal of Animal Ecology, Vol. 43/No. 3: 611-626. Accessed August 02, 2010 at http://www.jstor.org/stable/3526.

Hutterer, R., G. Amori, B. Kryštufek, M. Fernandes, H. Meinig. 2008. "Sorex minutus" (On-line). IUCN Red List of Threatened Species. Version 2010.2.. Accessed August 02, 2010 at http://www.iucnredlist.org.

Malmquist, M. 1985. Character Displacement and Biogeography of the Pygmy Shrew in Northern Europe. Ecology, Vol. 66/No. 2: 372-377. Accessed August 02, 2010 at http://www.jstor.org/stable/1940386.

Pernetta, J. 1976. Diets of the Shrews Sorex araneus L. and Sorex minutus L. in Wytham Grassland. Journal of Animal Ecology, Vol. 45/No. 3: 899-912. Accessed August 02, 2010 at http://www.jstor.org/stable/3588.

Rychlik, L., E. Jancewicz. 2002. Prey size, prey nutrition, and food handling by shrews of different body sizes. Behavioral Ecology, Vol. 13/No. 2: 216–223.

Rychlik, L., R. Zwolak. 2006. Interspecific aggression and behavioural dominance among four sympatric species of shrews. Canada Journal of Zoology, Vol. 84: 434–448.

Step, E. 1921. Animal Life of the British Isles: a pocket guide to the mammals, reptiles, and batrachians of wayside and woodlands. London and New York: Frederick Warne & Co. Ltd.. Accessed August 02, 2010 at http://www.biodiversitylibrary.org/name/Sorex_minutus#47.

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