One of my male gliders has scabs forming in his bald spot on his head...is he doing this to himself, or is this something that naturally happens?

Sometimes the bald spot will disappear, and it can look like scabs where the fur is growing back. I don't know if that's your case, but for our guy it looked kinda like scabs cause the fur was growing back slowly.

It may just be the oils produced by the scent gland drying. Try gently wiping his head with a damp wash cloth to remove some of the oil build up.

Neutering would cause him to loose the bald spot completely and reduce the smell also.