Sugar gliders can have mental health issues which can require a whole new level of patient understanding and unconditional forgiveness to lead them to a feeling of security, but the effort is worthwhile even if the progress is too slow to measure.
The most important thing to do is to show up and be present, everything else will follow from that, just spend as much time with them as reasonably possible for as long as it takes regardless of their desire for you to just go away.
When Shimmer came to me she had extremely high anxiety. Constant panicking crabbing to the point she would choke on it. This was triggered anytime anything moved near her. She would not tolerate a hand in her pouch. She employed fast and hard nipping to try to convince me out and then fetal position panic crabbing until she was exhausted. She would play keep away and hide during tent time sessions.
In the beginning, it was very hard to get her to trust me enough to take licky treats, and she didn’t eat mealworms, which sidelined my two most effective tools right at the start. The only bonding she would willingly do is to cower in a pouch under my shirt and crab at me all day, so we did an epic amount of that. After some weeks she came to take treats from me, and thankfully learned to eat mealworms after watching my other gliders love on them.
I could tell that in her heart she knew she was safe with me because she would drop the anxiety when a mealworm was on the line. I used them extensively to bribe her and train her to walk onto my arm or shoulder and i still make her eat the worm from my fingers to associate me with her favorite yummy. I probably went a bit overboard with this strategy once it started working because Shimmer added a good 30 grams onto her after having her first joey, Fade.
Ahh, yes, Fade was a huge help bonding Shimmer too. Shimmer was an excellent and protective momma, so I could lure her into any pouch Fade was sleeping in. She didn’t trust me with herself, but she fully trusted me to joeysit for Fade. 
Change came gradually. Crabbing sessions lessened over time in duration, intensity and frequency. She improved so slowly it was hard to see the progress until one day I realized it had been days since I last heard her crabbing and poked her to be sure she still had her attitude (she did). I was relieved, after a while I just came to love her for her her-ness, and enjoy the push button demo of crabbing for visitors.
She gradually began coming to visit me during playtimes even when I wasn’t pressuring her. She never stayed long at first, just a panicky jump to my shoulders and away again like she was fulfilling a dare. If i offered her a treat I could sometimes get her to stay long enough to sniff me down before running off. I would try to stay moving in circles to keep her as long as possible before she could line up a landing pad and sometimes this worked to just get her to settle out of reach in a shadow on my back.
Daily feather chases and waking them with treats (after making the treat sounds so they learn the association) slowly broke Shimmer’s habit of crabbing herself sick whenever she’s disturbed in her pouch. She came to feel excitement and anticipation whenever she heard me coming instead of abject terror. She now pops her head up and begs for mealies when I walk by her cage.
Hand bonding was probably the hardest and slowest of my training routines with her. Shimmer HATED having a hand in her pouch with her, hated it like I would hate being submerged in spiders. I could feel the revulsion and terror pouring off her and it was torture to her day after day. She would panic, rapid-bite, burrow into the corner, crab as intensely as I have ever heard (and Ive broken up a fair few glider fights), and eventually fight her way around my hand to escape, which I always allowed her to do as it taught her to walk onto my arm even if I was failing to teach her to snuggle my hand. She still isn’t a lover of hand bonding training, but she settles in to sleep now and no longer has panic attacks about it. She will still leave the pouch sometimes when she isn’t feeling the cuddle vibe, but in much less dramatic fashion than her old panic leap at the face escape routine.
“Stay with me” training Shimmer was awful. She was a panic leaper and was nearly impossible to lure once she was out. Only had one really bad escape into the main house area but it was a good 20 minutes of wild leaps and failed jumps and terror that she would find a hiding spot I couldn’t. A smart person would have taken the hint and stopped trying, but I was determined and eventually it has paid off. Shimmer is now absolutely perfect at stay with me training, and I have no hesitation bringing her out for a walk around the house anymore. She has become a regular helper when making glider dinnerplates. It just took doing it over and over again even when it wasn’t particularly safe or smart. I give gliders just a little more trust than they deserve, and let them earn it or lose it.
Shade, her husband, is amazingly patient with her and always lets her get her way. He comes up, takes a treat, delivers it to Shimmer at the bottom of the pouch, and comes back for his own. He understands her anxiety and often gently tries to protect her by sitting on top of her and making direct eye contact with me as if to say “she’s having a hard day, maybe do training later? Here, let me take your mealie gift to her, I know she will appreciate it.” She would follow him up my arm long before she would come on her own, so I used that trick generously and I think he was actively in on the plan because he would visibly encourage her to follow and give her a cloacal licking as a reward 
Its very heartwarming to watch them together. I think Shade is Shimmers emotional support glider 
So that was the last two years. Today is a whole new story. Shimmer has maybe crabbed at me twice in the last week. She readily climbs up my arm both in her cage (that took so much effort) and in the playroom (relatively easier). She comes to me looking for treats and is happy to stay on me during stay with me training. She pouches easily and lures with worms and feathers. I can pull her out of a pouch or hand bond her while in it. I can trim her nails and transfer her from pouch to pouch. It would now be hard to differentiate her from the others in my colony based on behaviors.
I don’t sense fear or anxiety from her anymore. When she crabs it’s indignant annoyance not sheer panic. When she leaps its a controlled jump with a safe landing. She only bites when she wants the worm Im holding and is gentle about it now. She doesn’t hide as much, she doesn’t run away as much, and she is content to sit my shoulder or forearm instead of insisting on being between my shoulder blades. She will happily stay sleeping in a bonding pouch with me all day and is nice about letting me know when she needs a drink or potty break (gentle painless scapes of her teeth on my exposed skin right above the pouch, this is actually Shade’s quirk but she has picked it up too).
Understand that you are teaching them how to communicate their needs to you by your responses. If they need a drink, how do you want them to tell you? If they need to potty, how do you want them to tell you? Decide that, and then always listen when they say it and always respond to it. This is a long-term training process but having these open lines of communication gives gliders a constructive way to communicate their needs instead of acting out in desperation.
When I got Shimmer I knew I could bond her, because I’m awesome and egotistical and really thought my glider guru game was top notch. But when she resisted every single trick I knew and even a few more I invented just for her, it shook my confidence. I was humbled by my constant failures with her, day after day, week after week, month after month! This was not what I had expected at all. I figured Id have her bonded to me in two months tops. Nope. I eventually came to accept her anxiety as a part of her personality.
With Shimmer, the only trick that really worked on her was patience and consistency, but it really did work. And the only trick that worked on ME was to love her as her. I would laugh when she bit me and give her extra petting and cuddles through her crabbing episodes instead of getting angry, hurt, or discouraged. Mood matters a great deal when communicating to a glider who can translate emotions better than words. I truly believe that gliders feel like we feel even if they don’t think like we think. Love and understanding during emotional turmoil is a language that transcends all barriers.
I use humor to stifle the anger response. When a glider bites me, I force a laugh and a smile. It makes a world of difference, and I swear it physically hurts less when I reframe that emotional component even when the smile is forced. This is a trick I’ve seen moms play on their toddlers too, make them smile and the ouchie doesn’t ouchie anymore. Works against yourself as an adult too, and its a life hack worth mastering if you have a biting glider.
This takes willpower and actively engaging mental strategies to avoid the instinctual emotional responses. Its hard to quell the natural reactions to a Gliders defensiveness. Its hard not to get mad when they bite, or want to leave them alone when they crab. Its hard to avoid feeling like they hate you. Indeed, for years whenever anyone asked about her my standard response was “Shimmer still hates me but thats ok, we’ll get there.” And we did. But we only did because I didn’t let her push me away. I didn’t listen when she crabbed to be left alone. I didn’t pull away when she bit me.
I didn’t let Shimmer have any negative power over me, but I gave her tons of positive power over me. If she wanted me to go away and she bit me, I stayed longer. If she wanted me to give her a worm and she walked onto me for it, I gave her all the worms she could eat. Positive reinforcement is a powerful tool. What you feed then grows, so feed the good behaviors and starve out the bad behaviors.
If your glider seems troubled, don’t take it personally and don’t give up hope that you can help them through it. Over the long-term they will respond to your love, acceptance, bravery, empathetic perspective, frequent presence and open communication.
