Sorex araneus, Linnaeus, 1758
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publication ID |
https://doi.org/ 10.5281/zenodo.6870843 |
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DOI |
https://doi.org/10.5281/zenodo.6869605 |
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persistent identifier |
https://treatment.plazi.org/id/3D474A54-A02F-8743-FF28-AC2615BDF7D7 |
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Felipe |
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scientific name |
Sorex araneus |
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Common Shrew
French: Musaraigne carrelet / German: \Waldspitzmaus / Spanish: Musarana bicolor
Other common names: Eurasian Shrew, European Shrew
Taxonomy. Sorex araneus Linnaeus, 1758 View in CoL ,
“ Europe .”
Sorex araneus has an interesting cytogenetic characteristic, a triplet of sex chromosomes that consists of one X-chromosome and two Y-chromosomes (Y, and Y,). A few more species of red-toothed shrews that also have such a triplet of sex chromosomes are similar in structure of nDNA and mtD-NA. They are usually combined into the araneus group. Robertsonian chromosome polymorphism is very common in S. araneus , with 76 chromosome races recognized so far. Each race has its own parapatric distribution. Such a high degree of parapatric chromosomal races is a unique characteristic of S. araneus . About 50 different forms have been described, but only two can be ranked as subspecies. Two subspecies recognized.
Subspecies and Distribution.
S. a. tomensis Ognev, 1921 — C & E Siberia E to SW Yakutia (= S.a. Republic). View Figure
Descriptive notes. Head—body 56-82 mm, tail 37-52 mm, hindfoot 12-14 mm; weight 5-14-5 g (immatures 5-10 g). Subspecies tomensis is bigger than the nominotypical araneus . Adult fur of the Common Shrew is trichromatic. Back is dark brown to almost black; sides are pale brownish, often with well-defined rusty hue; and belly is light grayish to lead gray. Demarcation of sides is distinct. Young are lighter than adults, and contrasts are less obvious: back varies from brown to dark brown,sides are slightly lighter, and belly is silvery gray to light gray. Tail is sharply bicolored. Karyotypes vary from 2n = 20 to 2n = 33. X-chromosome is large metacentric, and Y-chromosome and Y,chromosome are acrocentric. In the race with 2n = 20 (only females), all 18 autosomes are metacentric. In the race with 2n = 33 (males only), there are six metacentric and 24 acrocentric autosomes. Such variability developed because some acrocentric chromosomes could fuse into metacentric. The opposite process is also possible, when metacentric chromosomes fission to acrocentric and later fused into other combinations. This is the base for development of different chromosome races.
Habitat. Forests with predominance of deciduous species and grass cover, reforestations after fire logging, and less often broad-leaved forests. Density of the Common Shrew can be high in grassy meadows not used for haymaking and grassy marshes, but such open places are usually just temporary habitats. During summer, numbers of Common Shrews can be higher in open places than in forests. They avoid dark coniferous forests with moss cover and moss swamps. Exceptions are populations at the border of the distribution where Common Shrews occupy only limited habitats usually associated with river floodplains.
Food and Feeding. Diet of the Common Shrew includes a wide variety of food items compared with other congeneric species, presumably permitting high local densities. The Common Shrew eats adult and larval beetles, among which ground beetles ( Carabidae ), staphylines ( Staphylinidae ), and snapping beetle ( Elateridae ) are predominant. Common shrews prefer larvae of ground beetles and snapping beetle and adult staphylines. Earthworms ( Lumbricidae ), mollusks, arachnids (Arachnidae), and dipteran insects ( Diptera ) are also eaten. Diet composition differs among regions. Remains of vertebrates are rare in stomach contents of Common Shrews; frogs occur more often than mammals. Under experimental conditions the Common Shrew easily consumed small frogs. In winter, diet mainly consists of plants, primarily seeds from trees, spruce in particular.
Breeding. Ovulation of the Common Shrew is induced by copulation. Gestation lasts 24-25 days, and lactation lasts 19-20 days. Litters have 1-12 young, most often 6-7 young. Breeding occurs during the entire snow-free period. A female has up to three litters/season. Young-of-the-year can participate in breeding but not each year and mainly during conditions of low density or at the periphery of the distribution.
Activity patterns. The Common Shrew has polyphasic daily activity, with maximum activity at night (during summer). In autumn and winter, activity peaks in morning.
Movements, Home range and Social organization. Common Shrews are solitary, and they do not occur in pairs even during breeding. Sexual relationships are typically promiscuous. They have home ranges with no overlap among core areas. In experimental conditions, it was shown that individuals were more aggressive toward conspecifics than other species of shrews. One hectare can be occupied by up to 80 individuals, but typical densities are 20-30 ind/ha. In the Netherlands, home ranges were 400-450 m? in summer and 500-600 m* in winter. In spring, males leave winter home ranges and explore their surroundings in search of females, which are ready to reproduce. Females usually stay on their winter ranges and only slightly increase their area of occupancy at the expense of areas left by males. As young appear, they gradually colonize suitable territories, and by the end of summer, they push overwintered females that have finished reproducing from their territories. Older individuals cannot survive a second winter because their teeth are practically ground down, and second winter molt is not supported genetically for red-toothed shrews. The Common Shrew is the most numerous species of shrew in Palearctic and thus has a significant role in circulating organic material in an ecosystem; they recycle the equivalent of 100 times their biomass per year.
Status and Conservation. Classified as Least Concern on The IUCN Red List. The Common Shrew is one of the most numerous and eurytopic species of shrews, and it is usually more abundant than the other species of Sorex that it coexists with.
Bibliography. Bekenov et al. (1985), Buchalczyk (1972), Churchfield (1990), Churchfield & Sheftel (1994), Crowcroft (1957), Hausser et al. (1990), lvanter & Makarov (2001), Kalinin et al. (1998), Michielsen (1966), Moraleva & Telitzina (1994), Pavlova et al. (2017), Searle (1984), Shchipanov et al. (1998), Sheftel (2005), Sheftel et al. (2018), Yudin (1962), Zablotskaya (1957), Zaitsev et al. (2014).
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