Why can a sugar glider's tail not have a lot of hair?

If a male is not neutered, he will develop a bald spot on his head.

Other possibilities are that the glider is overgrooming or that there is an illness. Both cases need to be seen by a vet, as overgrooming can very quickly lead to self mutilating.

Remember that sugar gliders are not domestic animals. They have been taken overseas as exotic pets where, due to these delicate creatures being kept confined in cages, they are subject to stress. Stress is a large factor in this problem.