Sorex monticolus Merriam 1890

86. Montane Shrew Sorex monticolus French: Musaraigne sombre / German: Dunkle Rotzahnspitzmaus / Spanish: Musarafa de montana Other common names: Dusky Shrew, Mountain Shrew Taxonomy. Sorex monticolus Merriam, 1890, “ San Francisco Mountain, Arizona. Altitude 3,500 meters (11,500 feet),” Coconino County, Arizona, USA. Restricted by L. N. Carraway in 2007 to “latitude 33.70°N, longitude 108.96°W.” Widely used subspecific name longicaudus has been changed as the original name longicauda is a noun and thus invariable. Sorex monticolusis in the S. monticolus group along with S. neomexicanus and subgenus Otisorex. Sorex neomexicanus might be a synonym or subspecies of S. monticolus based on genetic data, although morphometric data support its specific status and it is recognized as distinct here until additional research is conducted. Sorex monticolus itself is largely paraphyletic because populations tend to fall into three major clades: Northern, Southern, and Coastal. Northern and Southern clades often group together with S. neomexicanus, and the Coastal clade is closest to S. pacificus and S. bairdi. Additional research is needed to resolve this paraphyly. Subspecific taxonomyis clearly in need of future research. Fourteen subspecies recognized. Subspecies and Distribution. S.m.monticolusMerriam,1890—C&EArizonaandWNewMexico(SWUSA)StoDurango(WMexico). S.m.alascensisMerriam,1895—W&SAlaskaincludingmanyoffshoreIs(USA). S.m.calvertensisCowan,1941—CalvertIoffWBritishColumbia(WCanada). S.m.elassodonOsgood,1901—QueenCharlotteIsoffWBritishColumbia(WCanada)andSAlaska(USA). S.m.insularisCowan,1941—S.m.IintheBardswellGroupoffWBritishColumbia(WCanada). S.m.isolatusH.H.T.Jackson,1922—VancouverI(SWCanada). S.m.longicaudaMerriam,1895—coastalSAlaska(USA)andWCBritishColumbia(WCanada). S.m.malitiosusH.H.T.Jackson,1919—WarrenIoffSAlaska(USA). S.m.obscurusMerriam,1895—NAlaskathroughWCanada(includingNWSaskatchewan)andWUSAfromNWashingtonandMontanaStoNewMexico(includingtheECaliforniaMts). S.m.parvidensH.H.T.Jackson,1921—SCalifornia(SWUSA). S.m.prevostensisOsgood,1901—Prevost(Kunghit)IintheQueenCharlotteIsoffWBritishColumbia(SWCanada). S.m.setosusElliot,1899—NWWashington(NWUSA)andtheSWcoastofBritishColumbia(SWCanada). S.m.shumaginensisMerriam,1900—PopofIintheShumaginIsoffSAlaska(USA). S. m. soperi R. M. Anderson & Rand, 1945 — C Saskatchewan and SW Manitoba (SC Canada). Descriptive notes. Head—body 53-76 mm, tail 42-61 mm, hindfoot 11-16 mm; weight 4-10 g. The Montane Shrew is medium-sized and hard to distinguish from the Vagrant Shrew (8. vagrans). Dorsum is brown to dark brown, occasionally with reddish tinge. Venter is buffy brown to grayish and is paler than dorsum. Tail is long, narrow, tipped with fur at end, and distinctly bicolored, being brown above and lighter below. Upper incisors are well pigmented and have pigmented tines; these teeth also have three denticles and wide interdenticular spaces. Teeth are pigmented dark red. There are five unicuspids, third is smaller than fourth, and fifth is minute. Habitat. Mostly alpine and boreal forests and coastal coniferous forests, associated with moist areas such as around streams or near bogs, being largely associated with riparian zones. In Mexico, Montane Shrews are found in montane pine-oak forests and can be found in spruce-fir and fir-larch forests in some regions. They typically are not found in open regions because of competition with Vagrant Shrews, but they are occasionally found in grassy meadows surrounded by forest. They are occasionally found in alpine tundra and sphagnum bogs. Food and Feeding. Seventy-seven to 99% of diets of Montane Shrews consist of various small invertebrates and conifer seeds, although fungi, lichens, and other plant material have also been recorded in diets. Soft-bodied invertebrates (earthworms, snails, slugs, etc.) and insect larvae make up significant proportion of diets, and maximum size of prey is ¢.30 mm. Foraging occurs along the ground by rummaging through leaf litter until prey is located. Breeding. Male Montane Shrews start to become reproductively active in mid-winter, and females become reproductively active around March. Although timing of reproduction can vary widely throughout a population, young are generally born in spring and summer. Litters have 2-9 young (average 6-4 young), and gestation lasts c.21 days. Females have postpartum estrus. Young are weaned at c¢.3 weeks old. Females can have 3—4 litters/season but do not generally survive to a second breeding season. Some young born early can breed in the same season they were born. Most individuals do not live past 16 months. Activity patterns. Montane Shrews are active throughout the day and year, but they can be more active at night similarly to other northern shrews. Nests are composed of dried grass and are spherical, being about the size of a human's fist. They use tunnels and runways to get around quickly. They might use echolocation to get around similarly to the Vagrant Shrew, although this has yet to be investigated. Movements, Home range and Social organization. Montane Shrews are solitary and highly territorial. Males have significantly larger home ranges during the breeding season (4020 m?in British Columbia) than females (1227 m? in British Columbia) because males drastically expand their home ranges to breed with as many females as possible. Densities and population size vary largely throughout the year, being highest during the breeding season and lowestjust before it because older adults die off in autumn after breeding and younger individuals overwinter to the next breeding season. Densities have been recorded at 12 ind/ha in autumn. Status and Conservation. Classified as Least Concern on The IUCN Red List. The Montane Shrew is widespread and common, although it might be affected by local deforestation and urban development in some regions. Bibliography. Alexander (1996), Carraway (2007), Demboski & Cook (2001), Esteva et al. (2010), Hawes (1976, 1977), Ingles (1960), Smith & Belk (1996), Terry (1981), Tobon (2014a).

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