Mountain bikers are tearing up natural areas around Kamloops and that has the City and naturalists worried about the impact.

While the areas affected might not seem like much — some dry grasses, a few sagebrush bushes — they are actually home to wildlife from mice to snakes and delicate plants like the mariposa lily, said Frank Dwyer, a member of the Kamloops Naturalists Club.

Dwyer has seen parents drive up and drop off their teenage kids to a vacant area at the end of 13^th Avenue where the grassland hill leads to the highway.

"I've seen adults bring kids here with shovels and bikes," he said Monday.

There, mountain bikers have dug holes in the silty earth and built up dirt ramps to jump off.

What they probably don't realize, Dwyer said, is they are tearing up an area where the land gets dotted with mariposa blooms in late June.

"This is one of the best beds of mariposa lilies here," he said. "Most of the flowers are inconspicuous until they bloom."

If picked, the entire flower plant dies. If the dirt is disturbed, natural plants won't grow there but invasive ones will, Dwyer said.

Not only are the cyclists unaware of the damage they're doing to the flora and fauna, but they are also probably blind to the fact their digging on the steep slope is leaving it prone to erosion.

An avid photographer as well as nature lover and hiker, Dwyer has noticed that in addition to building up the old jumps and trails, the kids are adding new ones already this spring.

City parks operations supervisor Shawn Cook said the location near Dwyer's home is provincial Crown land and a highway right-of-way.

"There's 10,000 hectares of Crown land within the City of Kamloops," he said.

Those complaints are forwarded to the province, which sometimes sends out work crews to take down the jumps.

But the City is also tackling an increasing number of illegal jumps and trails in its own parks and lands.

"It's getting worse, illegal jumps," said Cook.

Professional cyclists are creating big jumps, then videotaping their rides to post on the Internet. Once the filming is done, they move on to other sites, he said.

"Some are 10 to 20 feet high. They rip out the grasslands, they rip out the sage. They build this park. They video it. And it goes on YouTube or goes for sale and they never ride it again. Then they have these massive jumps kids could potentially ride on and potentially get hurt. We take this very seriously," he said.

The grasslands, which have taken hundreds of years to establish, are left destroyed, he said.

"When they're disturbed, they're not going to come back," said Cook.

"It's not just the jump, it's the trail to ride up to the jump and a trail to land on. It's a huge impact to the park."

The City is looking at an education campaign as well as stepping up bylaws patrols.

Anyone caught on the illegal trails or jumps could be ticketed.

City community safety and enforcement manager Jon Wilson said fines usually start around $100. But the damage from trails and jumps can cost thousands of dollars to repair.

"If we catch people with shovels and destroying, we may simply look at taking them to court and let the courts decide what the appropriate penalty or solution to the situation would be," said Wilson.

Cook said the City's nature park advisory committee will look at coming up with a strategy. That group includes the naturalists, bike park club and others.

"The damage is going to be long lasting. We take the jumps down, but there will still be a scar there," he said. "The unfortunate part is, the damage has been done."

Dwyer said he wants to see the City make environmental protection an important objective, including a plan to identify important natural areas. And, he suggests, it needs to start right away, so areas don't get lost.