The tiny warty jumping-slug, found only on Vancouver Island, is about two centimetres in length. (Contributed - Kristiina Ovaska)

The tiny warty jumping-slug, found only on Vancouver Island, is about two centimetres in length. (Contributed - Kristiina Ovaska)

Scientist leaping to the defence of Vancouver Island’s dwindling jumping slug

Mapping project tracks this important indicator of the health of B.C. rainforest

Ever thought about slugs? What about jumping slugs?

Probably not.

But they’re a thing – and they’re threatened, as first reported by KUOW Public Radio, the NPR affiliate based in Seattle.

Like the threatened spotted owl, slugs are important indicators of the health of Vancouver Island’s rainforest.

“They are important to forests,” said Jennifer Huron, provincial invertebrate conservation specialist with the B.C. Environment Ministry. “Like all biodiversity in the forests, they deserve protection and attention.”

The decline of two slug species on the south Island worries scientists: the dromedary and warty jumping-slugs. The species are both listed as threatened by the federal government.

The warty jumping-slug glides through the forests of the Sooke region. In contrast, the dromedary jumping-slug slimily slides through the undergrowth of the ancient forests of Port Renfrew along the coast to Pacific Rim National Park near Tofino.

And in case you were wondering: they do jump by flopping around on the forest floor – a defence mechanism, of sorts.

READ: One flush and it’s gone

Jumping-slugs primarily inhabit mature and older temperate rainforests. They require coarse woody debris and continually moist microhabitat to lay their eggs and take cover to minimize dehydration stress.

Slugs and snails play an essential part in the ecosystem by feeding on decaying and live vegetable matter like mushrooms, constantly turning over nutrients and keeping healthy the soil and plants that grow there.

“The fungi the slugs like are in the humus layer, so something has to come up and dig them up and disperse the spores, because they’re covered up,” said biologist Kristiina Ovaska. “It’s a fascinating interaction between the fungi, the trees and the little animals, such as slugs.”

“We don’t fully understand what each part of the ecosystem does or what these species do. The unique bits of DNA has been evolving for a long time. We really need to protect all parts to understand what they’re about fully.”

Dromedary and warty jumping-slugs are difficult to find, as they’re small and nocturnal and often hidden in leaves and fallen logs. Warty slugs are less than two centimetres in length, while the dromedary slug ranges in size from five to six centimetres.

“You really have to look for them, especially with a species that’s rare and patchily distributed. You need to know where to look and go out at night when it is raining,” Ovaska said.

A provincial mapping project is attempting to identify where the slugs live, with a view to accessing their habitat.

It’s not as simple as it sounds.

The slugs can only be found in the wet months of the year – March to May and September to October – and scientists need to be there while it’s raining heavily.

Huron said the plan over the next two years is to collect research material and create maps; they hope to leverage more money to protect the species. The maps will help to local government, industry and other property owners make informed decisions on the risk to the species.

“My job is to provide the science, and then others make those policy and socio-economic decisions,” Huron said.

ALSO READ: Habitat Acquisition Trust on mission to save frogs and newts

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