Ah yes, the ever popular skin between the thumb and pointer finger. Birds often love to explore that spot! And yes indeed it can hurt! It sounds like Bandit was responding well to the verbal cues to be gentle so Iād continue doing that. It will take time and consistency to see results. Since you said it was working during the day, Iād still consider that positive progress. You can also try the shunning method, putting him down on a neutral surface and turn your back to him for one minute. Easier to use that method with a clipped bird though.
When he was biting hard at night - can you think of anything that triggered it? Each time we get a hard or latched-on bite itās important to stop and think about the circumstances before the bite happened. Did something scare him? Did you pick up a new object he didnāt like? Was there a change in routine? Did you touch or grab him in a way he didnāt like? Even if you canāt find the trigger in a particular situation, itās a good habit to build. By thinking about the events before a bite I discovered my Conure has a particular dislike for me opening prescription medicine bottles
Itās annoying but at least I know what to look out for.
Even though they can be very painful itās important to try not to take bites too personally and not to hold a grudge. A bite is often not personal from the bird but instead is a reaction to a situation whether itās fear, curiosity, etc. Sometimes this can be hard to remember after receiving a really painful bite!
Good idea to keep Bandit separated from the other birds until he settles in more.