Overrun with wall lizards? Trapping is the best way to control the invasion

The invasion of the wall lizards is in full force in the capital region as the warm weather brings the little critters out to bask in the sunshine.

It has left a lot of people wondering how they can get rid of the prolific invasive species.

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Exterminators won’t touch them — and for good reason, as the placement of poisons can affect other species and cause a ripple effect on the birds, raccoons, cats and other animals that are developing a taste for wall lizards.

The only effective way is trapping, says Gavin Hanke, curator of vertebrate zoology at the Royal British Columbia Museum, who has been tracking wall lizards as populations have exploded over the past two decades.

He estimates there are 500,000 to 700,000 common wall lizards on Vancouver Island. The fast-moving lizards can grow up to 20 centimetres long from nose to tip of tail and range as far north as Campbell River. There have been new sightings on Salt Spring and Pender islands.

They are often hitchhikers in firewood and plants, and are spread by children who take them home as pets.

Hanke personally uses a simple rubber band, shooting it from his fingers to hit and stun the lizards so he can grab them.

He also uses a fishing rod with string and slip knot, laying the noose over the head or body and yanking it tight. Wall lizards can detach their tails as an escape method.

Hanke said residents are using deep buckets for captures.

A woman in Saanich has had success digging a trough and placing a five-gallon plastic pail at a 45-degree angle with a small amount of water. The lip of the bucket is close to ground and surrounded by sunning rocks. When the lizard goes to take a drink, it can’t get out.

Another resident places driftwood atop a pail for a basking spot. When the lizard is alerted to danger, it darts for cover and lands in the bucket.

“They don’t have sticky toes like geckos, so they can’t get out of the pail.”

How you kill them after capture is up to you. A crushing blow with a rock or brick is a quick end. Others bag and freeze them and later dispose of the bodies.

Evan Conway, a Saanich resident, says he has been trying to rid his property of the wall lizards for the past seven years after noticing their “overwhelming presence.”

“I have tried a couple of techniques, including traps and a plastic BB gun,” he said in an email.

But Conway said the most effective way is to place a smooth-sided bathroom waste bin between his Saanich garbage and compost bins, right up against the concrete wall on the south side of his house. “For some reason, just about every time I walk over to inspect, there is another lizard what has fallen into the can and can’t climb out.”

Hanke said some residents in the capital region use sticky-strip traps to capture the lizards — with one reporting he catches up to five pounds worth a week.

But Hanke discourages that, as well the air-soft guns that fire BBs and pellets.

“Sticky traps are shockingly inhumane, with animals stuck for a week in the blazing sun and cold at night,” said Hanke. “The traps are an attractant to predators who also get stuck. There also is too much collateral damage from other animals — snakes, native lizards and small birds, which will be attracted to insects and other animals in the sticky trap.”

As for air-soft guns, not a good idea, said Hanke.

“You can’t release something you shot and killed — if it actually was an [native] alligator lizard targeted by accident,” he said. “And wandering around with guns of any sort is a recipe for community stress — and our police departments I am sure would be happier not getting calls about people wandering around with firearms.”

Langford resident Jacquie Mutch said her property is crawling with wall lizards. When she and her husband moved into their home at the end of 2005, they noticed some alligator lizards and, later, wall lizards.

Wall lizards are known to eat their own young, as well as baby alligator lizards.

Mutch says the alligator lizards are gone now.

“We are now overrun with wall lizards,” she said. “They are everywhere, including in the walls of our stuccoed house and undermining our driveway. This year is the worst yet.”

Hanke said if residents want to prevent re-invasion after eliminating lizards, “you will need a serious barricading system, like corrugated metal siding inset into the ground.”

And to make your garden “uninteresting” to lizards, you’ll have to have a garden that is totally exposed and boring. That means no hiding places for quick retreats when a predator appears, no firewood piles, driftwood, rock beds or vegetable beds where they can lay eggs.

A close-cropped lawn is best with no other features. In- ground watering systems are attractive to wall lizards and they soon learn to drink from sprinkler heads.

“Lizards will lay eggs communally under paving stones, and at the edges of raised beds,” said Hanke. “Even the side of the house can be used as a basking site, and they can retreat under siding if there is a gap underneath – so vinyl or metal siding is best where they can’t climb it to escape predators and adverse conditions.”

Hanke said the introduction of wall lizards to Vancouver Island has been traced back to a roadside zoo in Central Saanich that closed in the early 1970s.

However, there may have been others that were pets and released in other places in the region.

Hanke’s research has noted the lizards have plenty of predators, from spiders to small song birds, herons and eagles. Recent photos also show robins and steller jays picking them up for lunch.

Among the species benefiting from the wall lizards is the American kestrel, the smallest falcon in North America.

Daniel Rondeau has been photographing a pair of kestrels feeding wall lizards to their young in Langford this spring.

“Our beautiful American kestrels benefit from this invasive species,” he said. “The parent kestrels catch one every 15 to 30 minutes on average at nesting time, which is happening now.”

dkloster@timescolonist.com

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