Territorial?

[Cubby]

My daughter received her very first hamster for Chirstmas and he has been a joy. Super fun and lovable. Since she received him we have added a few things to his cage but mostly just the basic set up. 3 days ago we decided to add some tubes and another small level. At first he did not want to have anything to do with it, would not even touch the tubes, within 24 hours he went crazy...loaded up all his bedding and food and moved it to the next level. He even filled in the tubes with bedding and ended up stuck on the second small level. We ended up getting him out but during the transition he ended up biting my daugther twice and drew blood. He has never done this before. Yesterday he was back at taking all the bedding up to the next level and packing his cheeks with the food. When my daughter tried to take him out to run in his ball (which he has always done) he made this noise and ran around crazy. She was scared and did not want to take him out because she did not want to get bitten again. I decided at this time to get rid of the extention and see if he goes back to normal. My question is has anyone experienced anything like this? Will he go back to normal? Should we leave the cage as is and take the extention back?
Thanks

[souffle]

It sounds like the he has developed cage aggression with the new part. Modular cages are really not ideal as they encourage this behavior and also set back taming due to the problems with the hamster hiding in tubes and small pods and the stress to get them out frightens them and means they will often bite as they feel 'cornered'
If you have a rotastack or ovo or crittertrail these are really not suitable for hammies despite what the shops tell you. Living in a tube is very unhealthy as they get all steamy and stored food gets damp and rots so the ham can get chest infections and tummy trouble from eating the food.
If you want to extend the cage it would be better to consider a much larger cage without tubes and with easy access. There are quite a few thread about this in housing and you can look at reviews in the cage review section.
Welcome to the forum

[Cubby]

Thanks so much, this is what I thought. He seems to be getting better right now by coming out when he hears her voice and she is still keeping to the routine that he has come accustom to. But, my daughter will not get him out of the cage without gloves on at the moment. We will look into the housing information here, he really did not need anything more, but my daughter wanted to get some tubes. That backfired

[Thin Lizzy]

There was a member who had this problem not long ago but I can't remember who! Sorry!
You were right to take the tubes out, I'm not a fan of several plastic tubes because of this happening plus if the hamster decides to use them as a toilet they can become awkward to clean and become very smelly.
Have you thought of getting a bigger cage?
Your daughter will have gotten a fright at being bitten so I would go back to the start and use the tissue trick and talk to him and praise him.
Also, hamsters can sense your mood, so if your daughter appears nervous he'll sense it.