They are, indeed, bells. Bells attached to giant rabbits no less. And Nephenee's at the back of the sled, smiling as she gives him a wave with one hand while the other opens the sack on the sled.

"Merry Christmas, Sir Yamanbagiri. Hope y'all're doin' good today. To answer your question, them's my sled bunnies, an' this is my sled. Say hi, girls." The rabbits all stood up momentarily on their back legs and looked at him, before flopping back down into the snow, jingling as they did. "Ah'm playin' Santa today."