Gee, the sketch is so awfully cute that I want to save it! I love your roly-poly fennec and bear designs! But I admit I am having a hard time following the story without extra cues, so maybe it needs tweaking a bit.
If you go with a fennec, maybe make it comically obvious that he's just arrived from warmer climes? Maybe he's dressed for summer and has a suitcase?
Also, @carolinedrawing has a good point: A desert fox's tracks in the sand wouldn't be so completely different from snow tracks as to be shocking. But some other animal's might be.
I think you've got a good start here, but it just needs some more thought. Sorry, I know that means hard work for you. For me, digging for a concept that works with the prompt is the hardest part! But your idea is a good one, and your sketch looks very promising, so it will be worth it!