The makeshift crosses left for victims of fer-de-lances didn’t rattle me much. The aggressive vipers thrive in the jungles of northeastern Guatemala and sometimes lay camouflaged along the trail we were following, but I figured I could spot their vivid yellow skin if I paid attention. I didn’t worry about the swarms of ticks, which are easy to spot, or the presence of jaguars and pumas, which are not. I didn’t sweat the guttural roar of the howler monkeys, or the deafening clat...
