Maybe you already knew that vultures sometimes eat their meals butt first. But did you know that the practice is becoming more common and that humans are kinda sorta to blame? I didn’t. And I haven’t felt this bad about human-inflicted suffering on animals since I wrote about sea lions getting deadly dementia from climate change.

(That was just a couple weeks ago. There’s a lot of stuff we should feel bad about.)

Nature can be a beautiful place, but it can also be really gross. Enter the vulture: These birds love them some fleshy meals, but they’re not designed to actually get to the good stuff themselves. They’re just not strong enough to tear into the skin of most big animals. Vultures rely on larger scavengers that can tear into flesh more easily. The vultures just swoop in and eat the leftovers. It’s a really good system.

But what happens when a vulture can’t count on buddies such as hyenas to do the hard work? National Geographic Explorer Jen Guyton explains that a hungry vulture will go straight for the softest parts of the body: the eyeballs and the butt.

Here’s where it gets worse: Guyton points out that human hunting has resulted in fewer big cats. Fewer big cats means fewer torn up carcasses, and that means more butt-first-eating vultures.

That approach exposes a vulture to even more bacteria than they’d get from regular old rotting meat. There’s strange fecal matter, obviously, but because the method of eating is slower, it also exposes the birds to more decay.

A recent study found that vultures have tons of microbes on their faces (528 different species, on average) but shockingly few in the gut (around 76 types). In fact, the only bacteria that survive in a vulture’s gut are the really nasty ones. It’s possible that the rest of the random microbes they’re exposed to just can’t compete. Meanwhile, vultures have somehow evolved to tolerate the bacteria that cause gnarly ulcers in humans, so they carry on none the wiser.