Sorex caecutiens Laxmann 1788
Creators: name: Mittermeier, Russell A.
name: Wilson, Don E.
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Mammalia
Soricomorpha
Soricidae
Sorex
Sorex caecutiens

description: 11. Laxmann’s Shrew <i>Sorex caecutiens</i> <b>French:</b> Musaraigne lapone / <b>German:</b> Maskenspitzmaus / <b>Spanish:</b> Musarana de Laxmann <b>Other common names:</b> Masked Shrew <b>Taxonomy.</b> Sorex caecutiens Laxmann, 1788, south-west shore of Lake Baikal, Siberia, Russia. Evidence from mtDNA and nDNA sequences classifies S. caecutiens in the caecutiens group. Eight subspecies recognized. <b>Subspecies and Distribution.</b> S.c.caecutiensLaxmann,1788—C&amp;ESiberia,fromtherightbankoftheYeniseiRivertotheLowerTunguskaandC&amp;SYakutia(=SakhaRepublic),andSSiberianMts(fromAltaiEtotheTransbaikalianridgesandWAmurRegion). S.c.annexusThomas,1907—KoreanPeninsula. S.c.koreniG.M.Allen,1914—Ntaigaandforest-tundrafromthePechoraRiverEtotheChukchiPeninsula. S.c.kunashirensisHutterer&amp;Zaitsev,2004—KunashirIandpossiblyHokkaido(Japan). S.c.laponicusMelander,1942—Fennoscandia,KolaPeninsula,andNtaigaofEuropeanRussiaEtothePechoraRiver. S.c.macropygmaeusG.S.Miller,1901—EAmurRegion,KhabarovskKrai,PrimorskyKrai,ShantarIs,MagadanRegion,andKamchatkaPeninsula. S.c.pleskeOgnev,1921—SforestsofEEuropefromPolandEtotheUralMts,middleandStaigaandforeststeppeofWSiberiaEtotheYeniseiRiver,andforest-steppeofKazakhstan. S. c. saevus Thomas, 1907 — Sakhalin 1. Also present in NW &amp; NE China and Mongolia, but subspecies involved not known. <b>Descriptive notes.</b> Head—body 50-73 mm, tail 28-45 mm, hindfoot 10-12 mm; weight 4-12-5 g (immatures 4-7 g). Body weight of young-of-the-year is almost 50% of that of overwintering adults. Overwintering individuals have brown back, reddish sides, and grayish belly, often pale yellow. In juveniles, grayish brown back gradually changes to light gray belly. Tail is sharply bicolored, being the same color as back in juveniles and substantially lighter than back in overwintering adults—a good feature for species identification. Chromosomal complement has 2n = 42 and FN = 70 (Chukchi population FN = 72 and Hokkaido population FN = 66), with 14 pairs of metacentric and submetacentric autosomes and six pairs of acrocentric autosomes. X-chromosome is large acrocentric, and Y-chromosome is small subtelocentric. <b>Habitat.</b> Siberian forests with pronounced moss cover. Laxmann’s Shrew is the most abundant species of Sorex in such habitats. It is often found in shrub (southern) tundra in the north and inhabits old broad-leaved forests without grasses and mosses in the southern European part of the distribution. It is comparatively rare in wooded steppe zone. Laxmann’s Shrew is often dominant or subdominant in the shrew community in the Siberian part of the distribution and is relatively rare in the European part. <b>Food and Feeding.</b> Diets of Laxmann’s Shrews consist primarily of spiders, centipedes, caterpillars, larvae, and adult beetles. Proportions of food items vary in different parts of the distribution. For example, adult beetles are preferentially consumed in Karelia and beetle larvae in central Yakutia, while beetles are not major components of diets in central Siberia and the Russian Far East. Consumption of plant material dramatically increases in autumn, winter, and spring; e.g. proportion of larch seeds in gastric contents reaches 73% from the region of the Omolon River, a tributary of the Kolyma River. <b>Breeding.</b> Mating of LLaxmann’s Shrew occurs from late April or early May to September in most regions. Females can produce up to fourlitters/season. Numbers of embryos/female are 1-12, averaging 5-7 in most of the distribution; however, a higher number of embryos is seen in northern regions (e.g. 8-6 in Kolyma River Basin). Female young-of-the-year often reproduce, but male young-of-the-year rarely do. <b>Activity patterns.</b> Laxmann’s Shrew has a multiphasic daily activity pattern, like other shrews. Relatively short periods of rest alternate with activity phases. Longest activity phases are observed at night in summer and shift to morning hours in autumn and winter. <b>Movements, Home range and Social organization.</b> Laxmann’s Shrew is solitary. Juveniles start settling in the second one-half of summer and establish their territories in winter. In spring, territories are maintained by most females and usually left by males. Females increase sizes of their territories in spring by adding neighboring territories that had belonged to males. Females bring up their offspring in these territories in summer. Adult males lack their own territories and move over large areas, which include territories of several females. Experiments with multiple species of shrews in one cage showed that Laxmann’s Shrews were less aggressive and more tolerant of each other than Common Shrews (S. araneus). <b>Status and Conservation.</b> Classified as Least Concern on The IUCN Red List. <b>Bibliography.</b> Bekenov et al. (1985), Churchfield &amp; Sheftel (1994), Churchfield et al. (1999), Dokuchaev (1990), Hutterer &amp; Zaitsev (2004), Ivanter &amp; Makarov (2001), Kalinin et al. (1998), Ohdachi (1992, 1994, 1995), Ohdachi &amp; Maekawa (1990), Ohdachi et al. (2009), Okhotina (1974, 1991), Shchipanov et al. (1998), Sulkava (1990b), Volpert &amp; Shadrina (2002), Zaitsev et al. (2014), Zima et al. (1998).
description: Published as part of <i>Russell A. Mittermeier &amp; Don E. Wilson, 2018, Soricidae, pp. 332-551 in Handbook of the Mammals of the World – Volume 8 Insectivores, Sloths and Colugos, Barcelona :Lynx Edicions</i> on page 398, DOI: 10.5281/zenodo.6870843