Vagrant Shrew(?) , photo by Hugh Griffith
Creatures Small But Great
A rustle - breathing from behind, a sudden pounce, a brief struggle - then
silence. The Nature Park is a dangerous place, and you visit at your peril -
if you are a small invertebrate such as an earthworm, wood bug or centipede.
A fierce predator relentlessly patrols the leaf litter and the underbrush.
It is the Vagrant Shrew, the smallest mammal in Richmond, with a body length
of about six centimetres.
The Vagrant Shrew is likely the most common of four shrew species found in
the Lower Mainland. It is cinnamon brown in summer, charcoal grey in winter,
has tiny, weak eyes, very small ears, and a long twitchy nose. To feed their
rampaging metabolisms, these animals are active round the clock, all year
long. They may eat 150 percent of their own weight in a day.
They frequent in the tunnel-like runs made by voles under logs or in dense
grass, which may explain why we are finding them as we trap for voles as
part of the Nature Park's Bioinventory. Then comes the fun - measuring them.
Sure, you've seen the Australian guy wrestling a croc, or subduing a King
Brown Snake. You've never seen him measure a shrew. Krikey! They are moving
at 78 rpm, while we are plodding along at 33.3.
Townsend's Vole, photo by Hugh Griffith
Voles are other small, seldom seen mammals abundant in meadows and wooded
natural areas. They are rodents, in the same group as lemmings and field
mice. Typically they stay under cover, living a somewhat frenetic vegetarian
existence while trying to remain undetected by predators such as birds of
prey, coyotes, raccoons, and, in winter, Great Blue Herons.
A relatively common species is the Townsend Vole. It is chocolate brown,
about thirteen centimetres long with a tail adding another six centimetres.
It is a prolific breeder and a major food source for the predators mentioned
above. It resembles a number of other vole species, including the much rarer
red-backed vole. One of the key ways of distinguishing among species of vole
is, again, measuring them. One of the required measurements is of the hind
foot. Nobody makes tiny vole-sized versions of those antique-looking devices
for human foot-measuring found lying abandoned under benches in shoe stores.
There is a steep learning curve in rodent wrangling, in mastering the
technique of gathering data from frightened, frantic little animals
possessing strong jaws and very sharp teeth, without causing harm to either
rodent or handler.
Shrews, voles - in any decently sized woodlot there must be hundreds of
these small mammals, doing what they have been doing for millennia. Obiwan
Kenobi, after the Death Star had obliterated the small green planet of
Alderaan, said, " I felt a great disturbance in the Force...as if millions
of voices suddenly cried out in terror and were suddenly silenced. I fear
something terrible has happened." I feel somewhat like Obiwan when I see
bulldozers spreading pre-load over a space that a week before had been a
forest. Assuming nesting season has ended, the birds have flown away. The small
things on the ground have not.
Hugh Griffith is a BC zoologist and science writer.