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Dwarf shrew

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(Redirected from Sorex nanus) Species of mammal

Dwarf shrew
Conservation status

Least Concern  (IUCN 3.1)
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Eulipotyphla
Family: Soricidae
Genus: Sorex
Species: S. nanus
Binomial name
Sorex nanus
Merriam, 1895
Dwarf shrew range

The dwarf shrew (Sorex nanus) is a species of mammal in the family Soricidae endemic to Arizona, Colorado, Montana, Nebraska, New Mexico, South Dakota, Utah, and Wyoming in the United States. The type locality is Estes Park (Larimer County), Colorado, USA.

Description

As described by its common name, the dwarf shrew is a very small species of shrew, usually weighing 1.8 to 3.2 g. It changes its pelage (fur) based on the season to aid in hiding from predators. In summer, the pelage is brown to olive brown on the dorsal side. This color extends down the side and merges with the smoke gray fur on its stomach. The tail is bicolored, a mixture of dark fur on top and beige fur underneath. During the winter, its pelage turns lighter and grayer, especially on its back, again to blend into the surroundings.

Phylogeny

The phylogeny of the dwarf shrew is very controversial. Given the sheer number of species in the genus Sorex, they are difficult to tell apart. A phylogeny is proposed, and widely accepted now, in which S. vagrans gave rise to S. nanus along with S. longirostris and S. ornatus. This same theory provides evidence that S. nanus and S. tenellus diverged more recently than their relatives because they are morphologically indistinguishable from each other except for very small size differences.

Distribution and habitat

The dwarf shrew lives primarily in mountain habitats, although it descends as low as 1400 to 1500 m in mountain ranges, the foothills of the Great Basin ranges and the Rocky Mountains. The ecological distribution of dwarf shrews is not fully known. They have mostly been reported from rocky habitats in the alpine tundra and subalpine coniferous forests. The dwarf shrew does not seem to be more tolerant of dry situations than its other shrew relatives. Dwarf shrews are also found in dry brushy slopes in Colorado around 1,670 m, in sagebrush-grassland in Montana at 1,036-1,128 m, and even at 750 m in Black Hills, South Dakota. This further adds to the mystery of their distribution. Dwarf shrew fossils have been found in late Pleistocene deposits in Hermit’s Cave, New Mexico, and Moonshiner and Middle Butte caves in Idaho.

In the past, mammalogists considered the dwarf shrew to be a rare species. From 1895 to 1966, only 18 sightings of the dwarf shrew were reported, but a study on a frog in 1966 led to the capture of 24 dwarf shrews using pitfall traps. Another reason that they were thought to be a rare species is that they have a very fragmented distribution throughout southwestern North America, and they are easily confused with their closely related shrew family.

References

  1. ^ Cassola, F. (2017) . "Sorex nanus". IUCN Red List of Threatened Species. 2016: e.T41406A115184594. doi:10.2305/IUCN.UK.2016-3.RLTS.T41406A22313099.en. Retrieved 8 November 2022.
  2. ^ Hoffmann, R., & Owen, J. (1980). Sorex tenellus and Sorex nanus. American Society of Mammalogists, 131, 1-4. Retrieved March 12, 2015, from http://www.science.smith.edu/msi/ Archived 2012-11-24 at the Wayback Machine
  3. George, S. (1988). Systematics, Historical Biogeography, and Evolution of the Genus Sorex. Journal of Mammalogy, 69(3), 443-461. Retrieved March 12, 2015, from JSTOR.
  4. Mullican, T., & Carraway, L. (1990). Shrew Remains from Moonshiner and Middle Butte Caves, Idaho. Journal of Mammalogy, 71(3), 351-356. Retrieved March 12, 2015, from JSTOR.
  5. Emslie, S. (2002). Fossil Shrews (Insectivore Soricidae) from the Late Pleistocene of Colorado. Southwestern Association of Naturalists, 47(1), 62-69. Retrieved March 12, 2015, from JSTOR.
  6. Hafner, D., & Stahlecker, D. (2002). Distribution of Merriam's Shrew (Sorex merriami) and the Dwarf Shrew (Sorex nanus) and New Records for New Mexico. The Southwestern Naturalist, 47(1), 134-137. Retrieved March 12, 2015, from JSTOR.

Further reading

  • Don E. Wilson & DeeAnn M. Reeder (editors). 2005. Sorex (Otisorex) nanus. Mammal Species of the World. A Taxonomic and Geographic Reference (3rd ed), Johns Hopkins University Press, 2,142 pp. (Available from Johns Hopkins University Press, 1-800-537-5487 or (410) 516-6900, or at JHU Press)
Extant species of Eulipotyphla
Atelerix
Erinaceus
Hemiechinus
Mesechinus
Paraechinus
Echinosorex
Hylomys
Neohylomys
Neotetracus
Otohylomys
Podogymnura
Crocidura
(White-toothed
shrews)
Diplomesodon
Feroculus
Palawanosorex
Paracrocidura
(Large-headed
shrews)
Ruwenzorisorex
Scutisorex
Solisorex
Suncus
Sylvisorex
(Forest shrews)
Anourosoricini
Anourosorex
(Asian mole shrews)
Blarinellini
Blarinella
(some Asiatic short-tailed
shrews)
Parablarinella
(some Asiatic short-tailed
shrews)
Blarinini
Blarina
(American short-tailed
shrews)
Cryptotis
(Small-eared
shrews)
C. mexicana group
Mexican small-eared shrew (C. mexicana)
Nelson's small-eared shrew (C. nelsoni)
Grizzled Mexican small-eared shrew (C. obscura)
Phillips' small-eared shrew (C. phillipsii)
C. goldmani set
Central Mexican broad-clawed shrew (C. alticola)
Goldman's broad-clawed shrew (C. goldmani)
Goodwin's broad-clawed shrew (C. goodwini)
Guatemalan broad-clawed shrew (C. griseoventris)
C. lacertosus
C. mam
Oaxacan broad-clawed shrew (C. peregrina)
C. nigrescens group
Eastern Cordillera small-footed shrew (C. brachyonyx)
Colombian small-eared shrew (C. colombiana)
Honduran small-eared shrew (C. hondurensis)
Yucatan small-eared shrew (C. mayensis)
Darién small-eared shrew (C. mera)
Merriam's small-eared shrew (C. merriami)
Blackish small-eared shrew (C. nigrescens)
C. thomasi group
Southern Colombian small-eared shrew (C. andinus)
Ecuadorian small-eared shrew (C. equatoris)
Rainer's small-eared shrew (C. huttereri)
Medellín small-eared shrew (C. medellinia)
Merida small-eared shrew (C. meridensis)
Wandering small-eared shrew (C. montivaga)
Peruvian small-eared shrew (C. peruviensis)
Scaly-footed small-eared shrew (C. squaipes)
Tamá small-eared shrew (C. tamensis)
Thomas's small-eared shrew (C. thomasi)
C. parva group
Central American least shrew (C. orophila)
North American least shrew (C. parva)
Tropical small-eared shrew (C. tropicalis)
Ungrouped / relict
Enders's small-eared shrew (C. endersi)
Talamancan small-eared shrew (C. gracilis)
Big Mexican small-eared shrew (C. magna)
Nectogalini
Chimarrogale
(Asiatic water
shrews)
Chodsigoa
Episoriculus
Nectogale
Neomys
Soriculus
Notiosoricini
Megasorex
Notiosorex
Sorex
(Long-tailed
shrews)
Subgenus
Otisorex
S. vagrans complex
Glacier Bay water shrew (S. alaskanus)
Baird's shrew (S. bairdii)
Marsh shrew (S. bendirii)
Montane shrew (S. monticolus)
New Mexico shrew (S. neomexicanus)
Pacific shrew (S. pacificus)
American water shrew (S. palustris)
Fog shrew (S. sonomae)
Vagrant shrew (S. vagrans)
S. cinereus group
Kamchatka shrew (S. camtschatica)
Cinereus shrew (S. cinereus)
Prairie shrew (S. haydeni)
Saint Lawrence Island shrew (S. jacksoni)
Paramushir shrew (S. leucogaster)
Southeastern shrew (S. longirostris)
Mount Lyell shrew (S. lyelli)
Portenko's shrew (S. portenkoi)
Preble's shrew (S. preblei)
Pribilof Island shrew (S. pribilofensis)
Olympic shrew (S. rohweri)
Barren ground shrew (S. ugyunak)
Subgenus
Sorex
S. alpinus group
Alpine shrew (S. alpinus)
Ussuri shrew (S. mirabilis)
S. araneus group
Valais shrew (S. antinorii)
Common shrew (S. araneus)
Udine shrew (S. arunchi)
Crowned shrew (S. coronatus)
Siberian large-toothed shrew (S. daphaenodon)
Iberian shrew (S. granarius)
Caucasian shrew (S. satunini)
S. arcticus group
Arctic shrew (S. arcticus)
Maritime shrew (S. maritimensis)
S. tundrensis group
Tien Shan shrew (S. asper)
Gansu shrew (S. cansulus)
Tundra shrew (S. tundrensis)
S. minutus group
Buchara shrew (S. buchariensis)
Kozlov's shrew (S. kozlovi)
Caucasian pygmy shrew (S. volnuchini)
S. caecutiens group
Laxmann's shrew (S. caecutiens)
Taiga shrew (S. isodon)
Eurasian least shrew (S. minutissimus)
Eurasian pygmy shrew (S. minutus)
Flat-skulled shrew (S. roboratus)
Shinto shrew (S. shinto)
Long-clawed shrew (S. unguiculatus)
S. gracillimus group
Slender shrew (S. gracillimus)
S. raddei group
Radde's shrew (S. raddei)
S. samniticus group
Apennine shrew (S. samniticus)
incertae sedis
Congosorex
(Congo shrews)
Myosorex
(Mouse shrews)
Surdisorex
(African mole
shrews)
Scalopinae
(New World moles
and relatives)
Condylura
Parascalops
Scalopus
Scapanulus
Scapanus
(Western North
American moles)
Talpinae
(Old World moles
and relatives)
Desmana
Dymecodon
Euroscaptor
Galemys
Mogera
Neurotrichus
Oreoscaptor
Parascaptor
Scaptochirus
Scaptonyx
Talpa
Urotrichus
Uropsilinae
(Chinese shrew-like
moles)
Uropsilus
Atopogale
Solenodon
Taxon identifiers
Sorex nanus
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