Sorex hoyi, Baird, 1857

Russell A. Mittermeier & Don E. Wilson, 2018, Soricidae, Handbook of the Mammals of the World – Volume 8 Insectivores, Sloths and Colugos, Barcelona: Lynx Edicions, pp. 332-551 : 419-420

74.

American Pygmy Shrew

Sorex hoyi

French: Musaraigne de Hoy / German: Amerikanische Zwergspitzmaus / Spanish: Musarana enana de América

Other common names: Pygmy Shrew

Taxonomy. Sorex hoyi Baird, 1858 ,

Racine , Wisconsin, USA.

Sorex hoy is in the monotypic S. hoy : group and subgenus Otisorex. It is sister to a clade including the S. vagrans group, the S. palustris group, the S. sonomae group, and the S. monticola group. Sorex h. thompsoni has been considered a separate species, but it is recognized as a subspecies here. Sorex hoyi has also been included in the genus Microsorex , but phylogenetic and

morphological studies place it firmly in Sorex . Six subspecies recognized.

Subspecies and Distribution.

S.h.hoy:Baird,1858—CanadafromBritishColumbiaandNorthwestTerritoriestoNewfoundlandandNW&NCUSA(RockyMtsofNEWashington,NIdaho,andNMontana,andfromNENorthDakotaStoIowa).

S.h.alnorumPreble,1902—fromEManitobaEtoWNewfoundlandandQuebecsurroundingtheHudsonBayinNECanada.

S.h.eximiusOsgood,1901—AlaskaandNWCanada(atleastinYukon).

S.h.montanusBrown,1966—SEWyomingandNCColorado,WCUSA.

S.h.thompson:Baird,1858—NEUSAfromSWisconsinEtoMaineandSECanadainNewBrunswick,NovaScotia,andPrinceEdwardandCapeBretonIs.

S. h. winnemana Preble, 1910 — EC USA from SE Pennsylvania S to NE Georgia and W to S Illinois.

Descriptive notes. Head-body 52-70 mm, tail 28-37 mm, hindfoot 10-12 mm; weight 1-7 g. The American Pygmy Shrew is relatively small but larger in northern parts of its distribution and smallest in the southern parts. Dorsum is coppery brown in summer and grayish brown in winter. Feet are pale. Tails are relatively short, narrow, and bicolored, being dark brown above and whiter below, with distinct tuft at tip. Teeth are dark reddish. There are five unicuspids, but only three are visible in lateral view because third, and fifth are minute. Provisionally, chromosomal complement has 2n = 62 and FN = 72, although additional research is needed to verify this.

Habitat. Moist forest and grassland habitats including woodlands, boreal forests, marshlands, bogs, and riparian areas from sea level to elevations of ¢.1640 m. American Pygmy Shrews are generally not found in dry areas, buy they are occasionally found in them.

Food and Feeding. American Pygmy Shrews primarily eat small invertebrates including various adult and larval insects (primarily beetles, lepidopterans, and flies), sowbugs, and spiders. Unlike many other species of shrews, earthworms and mollusks do not make up major proportions of their diets, possibly because they are too small to tackle such prey. In captivity, they have been known to attack grasshoppers, crickets, and various larval and adult flies and eat carrion. American Pygmy Shrews also eat seeds of jack pine ( Pinus banksiana , Pinaceae ) when food is scarce, and they might cache them.

Breeding. Reproduction of the American Pygmy Shrew seems to occur mostly in January-March, although pregnant and lactating females occasionally are recorded throughout much of the rest of the year, indicating that reproduction occurs yearround but most often in winter. Litters apparently have 5-6 young. The American Pygmy Shrew seems to be rather unique among Holarctic shrews because they can reproduce year-round, but additional research is needed on aspects of reproduction.

Activity patterns. American Pygmy Shrews are active throughout the day and yearround, using runways to move across the surface when foraging or tunnels under snow in winter. They dig tunnels or use those of other small mammals that no longer use them. Throughout the day, they spend much of their time resting with short bouts of activity to forage. Although they are widespread,little is known of its ecology, and additional research is needed.

Movements, Home range and Social organization. American Pygmy Shrews are probably similar to other Holarctic shrews in being territorial and solitary except during breeding and rearing of young. Densities have been estimated at 0-5—1-2 ind/ha.

Status and Conservation. Classified as Least Concern on The IUCN Red List. The American Pygmy Shrew has a very wide distribution, and it faces no major threats. Southern populations, however, might be threatened by urban and agricultural expansion; they are considered relatively rare.

Bibliography. Demboski & Cook (2003), Feldhamer et al. (1993), Foresman (1999), Jung et al. (2007), Long (1974), Mengak et al. (1987), Whitaker & Cudmore (1986), Whitaker & French (1984).

Figures

0. Radde’s Shrew (Sorex raddei), 1. Alpine Shrew (Sorex alpinus), 2. Ussuri Shrew (Sorex mwrabilis), 3. Chinese Highland Shrew (Sorex excelsus), 4. Greater Striped Shrew (Sorex cylindricauda), 5. Lesser Striped Shrew (Sorex bedfordiae), 7. Flat-skulled Shrew (Sorex roboratus), 8. Eurasian Least Shrew (Sorex munutissimus), 9. Azumi Shrew (Sorex hosonoi), 10. Slender Shrew (Sorex gracillimus), 11. Laxmann’s Shrew (Sorex caecutiens), 12. Shinto Shrew (Sorex shinto), 13. Taiga Shrew (Sorex isodon), 14. Long-clawed Shrew (Sorex unguiculatus), 15. Chinese Shrew (Sorex sinalis), 16. Common Shrew (Sorex araneus), 17. Iberian Shrew (Sorex granarius), 18. Valais Shrew (Sorex antinorn), 19. Crowned Shrew (Sorex coronatus), 20. Caucasian Shrew (Sorex satunin), 21. Siberian Large-toothed Shrew (Sorex daphaenodon), 22. Gansu Shrew (Sorex cansulus), 23. Tundra Shrew (Sorex tundrensis), 24. Tian Shan Shrew (Sorex asper), 25. Apennine Shrew (Sorex samniticus), 26. Arctic Shrew (Sorex arcticus), 27. Maritime Shrew (Sorex maritimensis), 28. Eurasian Pygmy Shrew (Sorex minutus), 29. Caucasian Pygmy Shrew (Sorex volnuchini), 30. Buchara Shrew (Sorex buchariensis), 31. Tibetan Shrew (Sorex thibetanus), 32. Kashmir Shrew (Sorex planiceps), 33. Trowbridge’s Shrew (Sorex trowbridgu), 34. Arizona Shrew (Sorex arizonae), 35. Merriam’s Shrew (Sorex merriami), 36. Alto Shrew (Sorex altoensis), 37. Jalisco Shrew (Sorex mediopua), 38. Saussure’s Shrew (Sorex saussurei), 39. San Cristobal Shrew (Sorex cristobalensis), 40. McCarthy's Shrew (Sorex mccarthyi), 41. Salvin’s Shrew (Sorex salvini), 42. Sclater’s Shrew (Sorex sclateri), 43. Pale-toothed Shrew (Sorex stizodon)

Subspecies and Distribution. S.h.hoy:Baird,1858—CanadafromBritishColumbiaandNorthwestTerritoriestoNewfoundlandandNW&NCUSA(RockyMtsofNEWashington,NIdaho,andNMontana,andfromNENorthDakotaStoIowa). S.h.alnorumPreble,1902—fromEManitobaEtoWNewfoundlandandQuebecsurroundingtheHudsonBayinNECanada. S.h.eximiusOsgood,1901—AlaskaandNWCanada(atleastinYukon). S.h.montanusBrown,1966—SEWyomingandNCColorado,WCUSA. S.h.thompson:Baird,1858—NEUSAfromSWisconsinEtoMaineandSECanadainNewBrunswick,NovaScotia,andPrinceEdwardandCapeBretonIs. S. h. winnemana Preble, 1910 — EC USA from SE Pennsylvania S to NE Georgia and W to S Illinois.