Why gerbils have fur?

Answer

The most common reason for missing fur on the tail is over-grooming by it's cagemates. The best way to prevent this from happening (since it is often due to being bored) is to give them plenty of cardboard and safe nesting materials. Other causes are:

The gerbil is rubbing it's tail on something in the cage- Removing the object.

Former injury- Hair sometimes won't grow back, Nothing to be worried about.

Malnutrition- Due to poor quality or not enough food. Make sure the food doesn't have too many "treats" in it.

Mites/Lice/Fleas- Which you can get checked out by your Vet

ANSWER #2

If you have two gerbils or more the other one may be chewing off the hair, i have dagu's--which are like gerbils-- and one of them is missing some hair on her tail, due to the other one. If you only have one, i might be chewing off the hair itself. It shouldn't be a big problem though, unless the gerbil is acting different about the missing hair on its tail.

someone or something may have pulled it off. i had one and someone pulled it off. it will look boney at first. but don't worry in a few hours it will grow back but not all the way.