When I want to wind up my green-leaning friends, I tell them about how I want to get a mountain bike and start riding in national parks.
With a rifle on my back.
I call it environmentally friendly feral animal reduction.
Here's a nice story (with video) on how a national park in the Galapagos has been clearing feral goats which have denuded the vegetation.
I worked on a sheep station up north for a short period and saw the damage that large numbers of feral goats did to the vegetation - essentially, they stripped everything bare and left a dust bowl behind. Since they could climb trees to a reasonable height, they took out the trees as well as the grass and shrubs. Unless you've been there and seen the goats in action, it's pretty hard to explain it to a Balmain dweller who hasn't set foot in anything rougher than their local council-provided landscaped park (with doggie cafe and nice lattes).
I've also been to Kakadu and seen the damage done by wild pigs around the water holes - it's really impressive. Greenies would go nuts if I drove my 4WD around and around a water hole and messed it up beyond belief, but they seem to have no issues with pigs doing the same damage (and more).
I'd steer clear of eating any pigs I shot due to worries about disease, but I am fond of goat curry. If I do splash out and get the mountain bike, the hunting licence won't be far behind.