In the village on Mramor, you can visit brown bears that were rescued from cruel captivity by the charity Four Paws. All the bears here were once kept in tiny cages as mascots for restaurants, but when the keeping of bears was outlawed in Kosovo in 2010, Four Paws stepped in to care for these wonderful animals. Sadly some of them still suffer from trauma and don't socialise well, but their excellent conditions are heartening indeed.
Ask to be let off any Gjilan-bound bus by the Delfina gas station at the entrance to Mramor, then follow the unsurfaced road back past the lakeside, and then follow the track around to the right. It's a 3km walk, and the gorgeous countryside and lake make a great spot for a picnic afterwards.