While some might find them gross, you could say that the animals we associate with garbage like opossums and raccoons are ecological success stories. We humans drastically change our environments wherever we go, yet these crafty critters figure out a way to thrive in our presence. They use our trash to survive.
“They’re very generalist omnivores,” Lisa Walsh, doctoral student in ecology and evolutionary biology at the University of Michigan, told Gizmodo. Generalist omnivores will eat animals, insects, and even fruits and vegetables. And they’re way more helpful for the environment than we think.
Opossums make up the largest family of Western Hemisphere marsupials—animals that give birth to underdeveloped joeys, which crawl into a pouch and attach themselves to a teat where they mature. You might hear people call it the “possum,” but “opossum” refers to the group of Western Hemisphere marsupials, while “possums” are a distantly related group of Eastern Hemisphere marsupials from Australia, Papua New Guinea, and Indonesia. The opossum you’re most likely to encounter in the United States is the Virginia opossum, the only species of opossum found north of Mexico and the only marsupial found naturally in the U.S.
Virginia opossums are quickly aging, short-lived mammals with a polarizing appearance and quite meme-able behavior: When threatened, they hiss or pretend to be dead, stiffening and even emitting a gross stench. They have naked tails like rats, are nocturnal, and are a common victim of vehicle strikes. Some people eat them.
The sum of their quirks combined with their diet leads to their association with trash in popular culture, Walsh explained. They probably go into your trash because it smells good to them, she said. And often another animal, like a raccoon, will have opened the trash can first, and the opossum just follows its nose into the buffet.
Non-food human garbage actually plays a surprisingly small role in the opossum’s diet, Walsh explained. Scrambled eggs and potatoes have been found in opossums stomachs, similar to foods they might eat in a human-less environment.
Opossums’ affinity for human-altered environments is apparent in the way their range is expanding. Though they typically avoid dense forests, forest clearing has created new, more welcoming habitats. In places like Michigan where they’ve begun to settle, opossums might not even rely on garbage for food. Though it’s mainly based on speculation, Walsh thought perhaps opossums in these environments settled in garbage bins to keep out of the cold.
But its a two-way street. Opossums show up in human habitats mainly because humans have shown up in theirs. “I always try to emphasize that we are in their habitat,” Anne Hilborn, science communicator with a Ph.D in wildlife conservation, told Gizmodo. “Animals are usually doing their best to try and adapt to our presence. Some animals are more successful at it than others.”
Walsh noted that we don’t associate squirrels with trash when they eat human-supplied food, but once an animal starts poking around in our trash, we immediately begin to think less of it. But opossums are largely beneficial to humans—their diets consist of slugs, mice, rats, and ticks, animals that we consider pests or disease vectors. One study showed opossums sweeping up ticks from the forest floor, then grooming off and killing most of the ones that stuck to them, exterminating nearly 6,000 ticks per opossum per week.
So they might love our trash—but they’re important neighbors who aren’t trash themselves, and they lived here before most of us did. Said Walsh: “They largely benefit us, so we should show them some love.”