A startup in the Swedish city of Södertälje, which is located near Stockholm, has recruited the help of local crows to pick up discarded cigarette butts from the city’s streets and public spaces. In fact, there’s a movement afoot in places as varied as California and the Netherlands to ban the sale of filtered cigarettes to help tamp down on their prevalence in our environment.

According to the Keep Sweden Tidy Foundation, more than one billion cigarette butts are left on Sweden’s streets each year, which represents 62 percent of all litter. To clear the streets, Södertälje spends around 20m Swedish kronor (over $2,200,000), so the hope is that the birds can help cut these costs.

“They are wild birds taking part on a voluntary basis,” the founder of the Corvid Cleaning startup Christian Günther-Hanssen reveals.

Each time the wild birds deposit a cigarette butt into a bespoke machine specially designed by Corvid Cleaning, they receive a little snack.

Günther-Hanssen estimates that, with the crows’ help, the city could save at least 75 percent of the costs associated with picking up cigarette butts in the city.

For now, Södertälje is trialing the project before setting the operation in motion across the city, paying close attention to the health of the birds, considering the kind of waste they’re being rewarded to pick up.

Research suggests that New Caledonian crows, a member of the corvid family of birds, have the reasoning ability of a human seven-year-old, making them the best bird for the job.

“They are easier to teach and there is also a higher chance of them learning from each other,” says Günther-Hanssen. “At the same time, there’s a lower risk of them mistakenly eating any rubbish.”

This story was part of our Best of 2022 series highlighting our top solutions from the year. Today we’re featuring our staff favorites. This article was chosen by Arielle.