Hi guys, my gf have 1 male glider about 3 or 4 months old, and he often barks at night. I know it is common for suggies to bark at night, but from what I have read, they bark to communicate...? So if a glider barks alone, what does it mean? Is he calling for human?

And also, her glider really likes to chew on her,which I also know is a common thing for glider. But he's chewing really hard. I also have 2 female gliders, and both of them bites, but not as hard as her glider. Is that because of her glider is a male? And is there any way to stop him to chew so hard?

You are right about barking being some type of communication. As for what kind, it is hard to say. It is possible that he is calling out for other gliders or he could just want some company. They are colony animals by nature. Is she planning on getting him a friend?
As for the chewing, he is still pretty young and still has some learning to do. He will test boundaries, and they like to bite and taste to figure out what some things are. She could try giving him some eucalyptus sticks to chew on, to maybe curb the urge. It's good for their teeth and they love it. I have one glider that still nips time to time though not nearly as much. He uses it to communicate with me letting me know he wants something. He will not and slowly crawl up to my face as to say "sorry but I want a treat!" there are things that can help like doing the ttssst sound, or blowing on them. They hate it, but mine figured out, if I yelp, it was too hard and the guilt cuddles begin lol it could also be a smell on her skin. She could try a different soap (fragrance free maybe.) I don't even use perfume anymore. I don't want to irritate them. Anyways, good luck with the barking and chewing

She already has 1 other glider, but in another cage because the new glider is not tamed yet, and she tried to introduce the two but it didn't really go well, so she's waiting for the glider to be bonded first, and then introduce them again.

So you can sort of train them to not bite you? That's really helpful, thanks! Will still try to get something for her glider to chew on. Thanks for the tips! :)