Monday, April 18, 2011

Tracking nature's not-so-cute critters

The blue-grey taildropper slug was first discovered on Vancouver Island by the Helsinki-born biologist Kristiina Ovaska. She photographed one of the slender critters atop a leaf.

By Tom Hawthorn
Special to The Globe and Mail
April 18, 2011


Pity the blue-grey taildropper slug.

Talk about poor public relations — slimy; scourge of gardeners; shares name with the habitually lazy.

Walt Disney gave cupboard-raiding vermin cutey-patootie cartoon treatment, but who champions the lowly terrestrial gastropod?

Kristiina Ovaska, that’s who.

She’s a biologist who likes slugs and snails and creatures that regenerate tails.

Not too much is known about the blue-grey taildropper. It is shy. It is small. It is extremely rare.

Its colour, as the name suggests, ranges from grey to blue with some light speckling.

“It has an unusual defence behaviour,” Ms. Ovaska noted. “If a predator grabs on the tail, the tail comes off just like a lizard. Then the slug can regrow the tail.”

So, the blue-grey taildropper was easy to name. But it was much harder to find

For two centuries of recorded history, no one knew the creature lived among us in its preferred haunts of Garry oak meadows and mature forests of Douglas fir.

Small and slender, stretching just three centimetres in full stride, the slug remained unknown in Canada until a certain biologist looked under a leaf at Rocky Point in Metchosin, outside Victoria, and — voila!

“I came across a tiny, little slug,” she said. “It could easily have been missed had I not been looking for them.

“I didn’t know what it was. I was interested enough that I thought, ‘I will take it home and grow it a little bit. I will try to find out what it is.’ ”

The specimen was placed in a modified temporary habitat retrieval carrier, which is to say a plastic yogurt container stuffed with moss with a lid in which breathing holes had been punched.

“Exactly like what a little kid would do,” the biologist conceded.

She sent photographs to molluscologists and fellow gastropod researchers in Oregon and Washington. Meanwhile, “I had this slug in my basement,” she said, a circumstance familiar to some parents. The creature was tentatively identified.

More specimens were rounded up. A genetic analysis was conducted. A dissection was performed. That confirmed the identity of Prophysaon coeruleum.

The taildropper provides a tasty hors d’oeuvre for birds scratching in leaf litter. The ground beetle considers the tail a complete meal in itself, a happy scenario for the slug considering the possibilites.

The original taildropper specimen now resides in a drawer at the Royal BC Museum. It is an ex-taildropper, sacrificed to science.

“You have to do that, so that there’s a permanent record and documentation,” Ms. Ovaska said.

“We don’t recommend people collect any specimens,” she added. The endangered slug is best recorded through photography.

This spring, the nonprofit Habitat Acquisition Trust is encouraging citizen scientists, especially those on the edge of preferred habitat, to check for the presence of such endangered creatures as the blue-grey taildropper slug, the western painted turtle, and the elusive sharp-tailed snake.

The trust encourages landowners to place moistened corrugated cardboard shelters for the slugs, as well as asphalt shingles for the snakes, who, like many southern Vancouver Island homeowners, prefer south-facing rocky hillsides.

At Swan Lake in Saanich, six turtles have been equipped with radio tracking, which has provided interesting preliminary insights into their behaviour. The turtles hibernate together in shallow water surrounded by willows.

It it is slimy, or slithers, or hops, Ms. Ovaska is interested. She wrote her masters thesis on the jumping mice of Nova Scotia. The Helsinki-born biologist has studied and photographed amphibians and other small creatures throughout Canada, Latin America and the West Indies.

“There is something mysterious about the small, hidden world that is all around us,” she said.

Gardeners, whether working in an Eden or an ordinary tomato patch, should encourage the presence of snakes, as they dine on several common garden pests.

But snakes perhaps should not be encouraged if one plays host to a population of blue-grey taildroppers.

“Here we have a dilemma,” Ms. Ovaska acknowledged.

Snakes consider slugs a delicacy.

The endangered sharp-tailed snake, including this specimen photographed near Vesuvius on Saltspring Island, is shy, likes the sun, and should be welcomed in any garden.