Led by Nessie O'Neil at Miami University, the team watched two juvenile female siblings play with paper balls they had made themselves and did not appear to be using as food.

While this type of play has previously been observed in some other mammal and bird species, this may be the first documented example in raccoons of deliberately transforming objects and then using the modified material for non-foraging purposes.

"This study documents a previously unreported behavior in the critically endangered pygmy raccoon," noted the researchers in their paper published in the journal Wild.

So what exactly were they doing?

Looks like fun

It began when an adult female attempted to wet paper waste before abandoning it. Shortly after, one of her juvenile daughters retrieved the paper, soaked it in water and rolled it in sand to form a compact ball. Her sister watched closely and tried to copy her but failed. So her helpful sibling finished the job. The animals then batted, chased and shared the balls.

But this wasn't a one-off. During regular monitoring of the site (a beach club with garbage bins nearby), they saw the raccoons make and play with the balls repeatedly.