2006 news releases
Unique-to-the-Island water shrew evolved in isolation Times Colonist (Victoria) Sun 22 Jan 2006
Page: D8
Section: Islander
Byline: Carrie West
Source: Times Colonist
It's a miracle! The water shrew can walk on water. Actually, it runs on water, for a little while anyway. This mouse-sized creature actually traps air bubbles under its hairy feet, allowing it to "float" on the water's surface.
On Vancouver Island, we have a special water shrew. It's part of the common water-shrew clan that runs around North America, including mainland B.C. But our Vancouver Island water shrew developed in isolation, as many Island creatures do, evolving over thousands of years into what is currently considered a distinct subspecies.
Too bad we don't know much about it. The provincial government, responsible for managing this presumably rare species, conducted a scaled-back study in 1996 and 1997. Some water shrews were caught, but not enough to determine important issues like habitat needs and distribution.
The province also doesn't have a photograph of this special shrew. It's a little disconcerting, as photos of endangered creatures help enormously with public education, a vital component of species-at-risk conservation.
It's actually tough to catch a live shrew -- these water shrews have an extremely high metabolism and must eat every few hours or they die. So biologists trapping the creatures must be Johnny-on-the-spot if they want a live one -- an expensive, labour-intensive process. Our Vancouver Island water shrew might only live for six hours if trapped without food, according to Vanessa Craig, a contract biologist who spent time in 2002 and 2003 working on a shrew study for B.C. Hydro.
Hydro's Bridge-Coastal Fish and Wildlife Restoration Program provides $1.7 million per year for research into coastal creatures affected by hydro activities. Our lucky water shrew spends its whole life hugging the water or diving into it, so it received the extra research time.
Craig tried to find one of the Island water shrews in the Elk Falls area near Campbell River, setting 100 traps multiple times over two years, for a total of about 3,500 attempts. It's kind of depressing that not one shrew was caught -- dead or alive. The only one caught was found last summer by another biologist near China Creek in the Port Alberni area, despite more than 3,000 hours of trapping.
Historically, water shrews have been found from the Island's northern tip to the south. Although they do get caught in fisheries minnow traps, few total specimens have been collected, so these solitary little mammals seem rare here. Yet the common water shrew, also known as the navigator or American water shrew, is considered widespread in Canada and also inhabits southwestern Alaska and northern mountainous areas of the U.S.
Water shrews may look like rodents but actually belong to the mole family. They have five toes (most rodents only have four on their front feet). Shrews also have a long snout and sharp teeth. And of course, there's that nasty temperament, which Shakespeare made famous in The Taming of the Shrew.
According to Craig, water shrews are territorial in captivity when they're stressed out and in small quarters. But in order to discover just how nasty our Island shrew can be, a wild study would need to be done. Maybe someone can take a picture, while they're at it.
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All About the Water Shrew
Species: Vancouver Island Water Shrew (Sorex palustris brooksi)
Location: Vancouver Island
Official Status: Red-listed (provincial) Number remaining: Unknown Ecological significance: Only water shrew on Vancouver Island. Currently recognized as a distinct subspecies, as it has evolved in isolation from other common water shrews.
Favourite food: Aquatic invertebrates; slugs, snails, spiders and small fish.
Favourite habitat: Riparian habitat (creeks and streams, possibly bogs and marshes) Key threats: Degradation of riparian habitat due to urbanization and forestry. Also, habitat fragmentation.
