As with most birds, food sources are always a draw, but ravens might also decide your home is the perfect place to rest or even nest.

As temperatures drop and natural food sources become harder for wildlife to find, your yard can become an important refreshment stop for winter birds. But simply getting whatever bird feeder you can find and filling it with seed isn’t always helpful. The type of feeder, where you place it and how often you clean it can all affect which birds show up and whether you accidentally invite squirrels, mice and other pests into your yard as well.

From deterrents to yard changes, these expert-backed tips can help make your outdoor space less appealing to crows—without putting them at risk.

In March of this year, a team of scientists—led by Emil Ruff, a Ph.D. in microbial ecology—descended into a 2.2-mile-deep mineshaft just outside of Johannesburg, South Africa. The NASA-funded expedition had an unusual objective: to research a billion-year-old brine discovered after an earthquake split a tunnel wall. That radioactive brine contains microbes, argon, phosphorus … and oxygen. Scientists call it “dark oxygen,” oxygen produced without photosynthesis. Ranjani Murali, assistant professor of microbial environmental genomics at UNLV, was on that expedition along with Sujung Lim, a postdoctoral scholar from Murali’s lab.

Don’t brush it off as just another bird. From scientific reasons to ancient spiritual symbolism, here is what that repeated visitor is really trying to tell you.

The next time you’re in one of Toledo’s 19 Metroparks, you might see a bunch of 4 feet tall plastic tubes with trees growing out of them. But that’s not litter: those plastic tubes are actually helping the trees grow.