Cowichan Valley amphibians at risk from vehicles
Development around wetlands also a concern
Elke Wind is the frog lady. I catch up with the biologist on an inky, rain-lashed evening on Riverbottom Road in the Cowichan Valley while she conducts a survey of amphibians along a one-kilometre stretch of pavement.
Amphibians can be difficult to spot since they are generally nocturnal and tend to hide in forests and wetlands.
Not tonight. After a summer of unusually dry warm weather, the first heavy rains of the season have them on the move — in big numbers and in the open.
“Amphibians have sensitive skins so they need to be in moist environments,” explains Wind, on contract to the Ministry of Transportation and Infrastructure.
“When it gets hot and dry they basically have to hunker down or hang out where there’s water. When it rains, all of a sudden it’s like being set free.”
Unfortunately, their movements can put them at risk of being killed by motor vehicles.
“I get them in all sorts of states, which is quite sad,” she says, adding: “I can be driving on a road at night and I can smell squished amphibians. It’s like a rotting smell.”
Wind carries a flash light and head lamp. She just bought a new rain jacket, but it’s already leaking.
When she spots an amphibian — dead or alive — she records the position from her GPS as well as the species and life stage.
I volunteer for the grunt job, employing tweezers to flick the guts to the road side so they won’t be counted again during subsequent surveys.
When we spot a live native amphibian, we carefully place it onto vegetation on the roadside to help keep it safe. If the creature is facing the right side of the road, that’s where it gets put. “Hopefully, they won’t go back onto the road,” Wind says.
Salamanders have smooth skin and are fast wrigglers. Rough-skinned newts are much slower; they’re poisonous, so don’t have to hurry.
Soon into our walk we spot a large adult bullfrog. It's an introduced species and eats pretty much everything, including native frogs and even juveniles of its own species.
Further along, large numbers of green frogs show up. They, too, are an introduced species and belong in eastern North America. Adults resemble bullfrogs, but smaller.
And so it continues.
We spot the severed tail of an ensatina salamander that eerily still twitches. The species can regrow its tail and has no lungs, breathing instead through its skin.
The tiniest amphibians we encounter are Pacific treefrogs, some smaller than the gravel used in the highway. “We get a lot of juveniles at this time of the year,” Wind says.
We wear reflective vests, but the work still has risks, especially on a night with poor visibility. Vehicles whip along the highway. A few slow down out of curiosity. One man parks his truck, activates the flashers, and talks about amphibians on his own waterfront, acreage property.
Later, two men in an off-road vehicle do a U-turn and ask if everything is ok. In the process, they run over an adult bull frog.
“Want a beer?” one asks.
Such vehicles can also destroy amphibians while off-roading on adjacent lands.
Roads are a fatal attraction to amphibians because they make easy pathways and retain the day’s warmth. Wind fears that the body count will only worsen as the Cowichan Valley's human population grows.
“It really worries me that at some point the traffic will push them over the edge. We’ll have too many getting hit and they won’t be able to recover.”
Earlier this year, the province installed a series of underpasses and directed fencing to reduce the carnage of western toads moving between Wake Lake and adjacent forest areas. Unfortunately, a residential development across the street stands to diminish the species’ habitat and generate even more traffic.
While the network of underpasses and fencing appears to have had a positive effect, it is limited and cannot protect all amphibians. Some species can also hop or climb over the fencing en route to winter hibernation sites.
After about three hours, the final tally is 228 individuals from nine species, including the northern red-legged frog, western toad, and long-toed and northwestern salamanders.
About half of the total are non-native green frogs.
And 61 per cent of all these amphibians are roadkill.
What more can be done?
Wind co-authored a 2020 BC government document offering guidelines on road building to help mitigate the impact on amphibians.
Reduced density of development in rural areas near wetlands would also limit impact on amphibians.
And individuals can make a difference simply by changing their driving patterns. “I’m always telling people: ‘These first few big rains of the fall, try not to drive at night.’
“We’re all responsible.”
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(Isabelle Groc photo of Elke Wind and western toad; BC Government photo of green frog).
— Larry Pynn Sept. 20, 2021