ARCHER’S POST, Kenya — Julius Lokinyi was one of the most notorious poachers in this part of Kenya, accused of single-handedly killing as many as 100 elephants and selling the tusks by the side of the road in the dead of night, pumping vast amounts of ivory into a shadowy global underground trade.

But after being hounded, shamed, browbeaten and finally persuaded by his elders, he recently made a remarkable transformation. Elephants, he has come to believe, are actually worth more alive than dead, because of the tourists they attract. So Mr. Lokinyi stopped poaching and joined a grass-roots squad of rangers — essentially a conservation militia — to protect the wildlife he once slaughtered.

Nowadays he gets up at dawn, slurps down a cup of sugary tea, tightens his combat boots and marches off with other villagers, some who had never picked up a gun before and are little more than volunteers, to fight poachers.

“We got to protect the elephants,” said Mr. Lokinyi, whose hooded eyes now glow with the zeal of a convert.