Identification of Pacific water shrew Photo credit: C. Schmidt
Prepared for: South Coast Conservation Program Species at Risk Training for Professionals Workshop 2: Pacific water shrew habitat management March 11, 2008 By: Vanessa Craig, Ph.D., R.P.Bio. 406 Hemlock Ave., Gabriola Island, BC V0R 1X1 Tel: (250) 247-7435 Email: Vanessa.Craig@EcoLogicResearch.ca www.ecologicresearch.ca
C. Schmidt Description Semi-aquatic shrew Largest shrew in the province Specially adapted for semi-aquatic lifestyle L. Evans D. Knopp
Other small mammal species Common name Pacific Water Shrew American Water Shrew Wandering Shrew Dusky Shrew Common Shrew Trowbridge s Shrew Deer Mouse Red-backed Vole Townsend Vole Creeping Vole Long-tailed Vole Heather Vole Townsend s Mole Coast Mole Shrew-Mole Scientific name Sorex bendirii Sorex palustris Sorex vagrans Sorex monticolus Sorex cinereus Sorex trowbridgii Peromyscus maniculatus Clethrionomys gapperi Microtus townsendii Microtus oregoni Microtus longicaudus Phenacomys intermedius Scapanus townsendii Scapanus orarius Neurotrichus gibsii
Identification An identification key (Nagorsen 2002) to identifying small mammals is available on the www. Location is in BMP. Key in Nagorsen (2002): Pointed snout that extends well beyond the mouth, eyes tiny Insectivores Front feet large with broad palms and long claws Moles Front feet not enlarged; palms not broad; claws not long -- Shrews Snout not strongly pointed and extending well beyond mouth, eyes not tiny -- Rodents
C. Schmidt Mice Note the large eyes, large filmy ears Have brown to grey coat, white belly Do not have shrew-like nose Shrew pelage denser
C. Schmidt Voles Larger than shrews Have larger eyes, more noticeable ears Heavier bodied Shrew pelage denser Red-backed vole Long-tailed vole Creeping vole
NW Wildlife Online B. Brett C. Schmidt Moles Larger than shrews No external ears, eyes not noticeable Heavier bodied Enlarged fore-feet Shrew-mole Mole Bristle-brush tail
Shrews Key from Nagorsen (2002): Total length greater than 130 mm, hind foot length greater than 18 mm, and usually with a fringe of stiff hairs Water shrews Total length less than 130 mm, hind foot length less than 19 mm, and lacking a fringe of stiff hairs other shrews L. Evans
Shrews Common Dusky Trowbridge Vagrant Am. water PWS Total length 99 76-119 117 93-140 118 101-128 104 85-126 152 133-179 154 137-176 Tail 42 51 55 42 75 70 29-49 35-68 41-62 32-58 62-88 61-81 Foot 12 14 13 12 20 19 9-14 10-18 10-15 9-15 16-28 16-21 Wt 4.1 6.6 5.6 5.3 10.6 13.2 2.8-8 3.7-13 3.8-8 3-10 7.5-16.4 10-20
Water shrews Pacific water shrew is most likely difficult to distinguish from the American water shrew How can they be distinguished? The American water shrew has: dark grey (can be brownish) to black dorsal fur (PWS has dark brown to black) A silver-grey/white belly (PWS has dark brown ventral fur can be lighter in the winter) A bi-coloured tail with a paler underside (PWS has unicoloured dark brown tail) More conspicuous fringe of hairs on its feet D. Knopp R. Forbes
Water shrews This PWS was likely a juvenile was 9.2g, 125 mm long, tail 56 mm long, hind foot 14 mm -captured in minnow trap -has foot hairs M. McArthur
Shrews Common Dusky Trowbridge Vagrant Am. water PWS Total length 99 76-119 117 93-140 118 101-128 104 85-126 152 133-179 154 137-176 125 Tail 42 51 55 42 75 70 56 29-49 35-68 41-62 32-58 62-88 61-81 Foot 12 14 13 12 20 19 14 9-14 10-18 10-15 9-15 16-28 16-21 Wt 4.1 6.6 5.6 5.3 10.6 13.2 9.2 2.8-8 3.7-13 3.8-8 3-10 7.5-16.4 10-20
When you capture a shrew All shrews captured should be measured Total length, tail length, and hind food length, and weight if possible Remember to check for foot hairs on all relatively large shrews Shrews suspected of being PWS should be photographed Pay attention to documenting length of body and tail, colour of belly and underside of tail, as well as presence of hairs on hind feet Record age and breeding condition if known Fill out a Rare Vertebrate Animal Observation Form and submit to Conservation Data Centre and MoE Submit all photographs, measurements, trapping and habitat info to MoE