It's hard work being high on the food chain, and predators are always looking for labor-saving ways to catch prey. In national parks in Kenya, the lions have not only gotten blasé about trucks full of ecotourists, they've started to use them as cover. They'll sneak around behind a vehicle and then rush out to lunge at a wildebeest. Imagine you're the wildebeest – one minute you're making sure they get your good profile, and the next minute you're running for your life.
In the Canadian Pacific, biologist Alexandra Morton was observing killer whales She was disconcerted by the way one of them, Kwatsi, kept surfacing directly behind her boat. “No matter how I tried to alter my course, his 5-foot fin stayed right behind my engine. After a while I realized what he was doing: Kwatsi was using my boat and its engine noise as a moving hunting blind.” Great minds think alike. “These humans mean me no harm. They are friendly! Friends help friends catch dinner.”
I performed a similar function once, without actually being a human shield. Driving across Florida, I pulled over to eat lunch at a picnic table, and tossed crumbs from my sandwich to minnow-sized fish in the waterway next to the road. The tiny fish were thrilled with the crumbs and mobbed them enthusiastically. As I gazed at them I heard a small clomp! and then another clomp! Two minuscule alligators had cruised up, disguised as minuscule floating logs, and were snapping up the fish I had lured to their doom. Oh yeah, they call this road Alligator Alley.
To be fair, I should have thrown the fish an alligator purse. They could have nibbled on it after it decayed a bit. But I didn't have an alligator purse. That's how it is. You try to pack everything, and you pack all this stuff you never use, and then the one thing you don't pack, you wish you had. It's hard to be a responsible ecotourist.