INTERNATIONAL: Cigarette butts are the No. 1 form of plastic pollution, with around 4.5 trillion tossed cigarette butts in the world today. In Sweden, a company called Corvid Cleaning is using crows to pick up this discarded waste.

For every butt deposited, the birds earn food. They collect the cigarettes, then drop them off in a specially designed machine. The founder of Corvid Cleaning, Christian Günther-Hanssen ,says the birds are still wild but are participating in the cleanup “on a voluntary basis.” The scheme is currently undergoing a pilot project, so the company can evaluate the birds’ health.

While trillions of cigarette butts make their way into the environment globally, the Keep Sweden Tidy Foundation estimates that there are over 1 billion cigarettes in the country alone. This type of waste makes up 62 percent of all litter, as reported by The Guardian.

A Swedish enterprise is testing a reward-based system in which wild birds help humans pick up trash.

Crows picking up training sticks and dropping them into a bin. Peanuts are then dispensed as a reward.

''The bin will tell litter apart from other items such as stones and leaves and only reward litter. The birds take part as much or as little as they wish, and the only human involvement is to empty the bin and refill the food,'' read a description on their website.

Corvid Cleaning is preparing a pilot project that would see the birds pick up "real litter" instead of litter set out specifically for them.

^{PHOTO: CROWS PICKING UP STICKS THAT LOOK LIKE CIGARETTE BUTTS AS PART OF TRAINING EXERCISE, CROWS BEING REWARDED WITH PEANUTS}