Ear nibbling

Question
Hello there,
We have two female guinea pigs.  They are approximately 5-1/2 months old and are supposed to be siblings.  They seem to get along pretty well.  Recently I have noticed one nibbling on the ear of the other.  It doesn't seem to hurt her as she most often stands still for it. However, one time she did run into the pigloo.  This ear has the fur chewed off the the lower part of the ear (the part that is not attached to its head).  There aren't any raw spots, but it is balding.  I was wondering if there is some sort of safe type of bitters or chewing deterrent I could put on this ear that would be safe for the guinea pig while making this behavior less desirable for the chewer.  I'm afraid of an injury as we did purchase a guinea pig a long time ago that had been bullied and had chewed ears.  

Thank you so much!
Maria

Answer
From your description this bald spot sounds like the same little bald spot that every guinea pig has. I used to tell the children that were getting pigs for the first time that God made that little spot bare because it's the perfect spot to kiss when you're holding your pig on your shoulder.

This sounds like the typical grooming behavior that many animals will do to one another. Horses, dogs, cats, birds, monkeys and many more will either use their fingers if they have them, or their teeth (as with dogs or horses).  It's not an aggressive behavior, but rather is a loving act of kindness. It's how they bond, much as mother's with babies will stroke their heads or arms.

If the pig being groomed didn't like it she would bite the 'hairdresser' and let her know she doesn't want it. The pig doing the grooming may be just displaying maternal behavior such as a mother pig does her babies. It's natural for them to do this and is not in any way harmful.