Introducting Older Rats

Question
Hi there,
We've sought your advice in the past about our rat, Bear, who had sarcoma. We always appreciate your ideas and have come with another question.
We recently adopted a rat named Charlie, approximately 3 months old. Our colony recently underwent a major shift after losing their long-time alpha rat, Stuart. We adopted Charlie shortly before Stuart's passing and are having difficulties introducing Charlie to our colony which consists of 4 male rats each one year or older. After the quarantine period, we placed Charlie's cage next to the large colony cage so they could smell each other. After this, we did introductions in a bathtub and on the staircase. Charlie's been somewhat defensive and has not shown an interest in submitting to the older rats. He ducks, hides and generally resists any sniffing or natural wrestling when the boys come to investigate. We also tried cage switching, where we placed Charlie in the colony's cage to get his smell everywhere and placed the colony members in his cage. Eventually, Charlie came to get along with two of our more subordinate rats, Pippin and Milo. Charlie, however, does not get along well with our more dominant rats Niko and Mosey. We continue to expose Charlie to the other dominant rats, but each time they have been together, Charlie sustains some sort of bite or injury. We would like all of the colony members to get along, but they are struggling to establish rank. We have tried cleaning cages, vanilla extract, yogurt baths (so they lick each other), but so far, Charlie has not been well integrated into the colony. Currently, he is living with the two subordinate rats to keep him company. Anything we should try that we haven't thought of? Thanks in advance for all of your help!
-Susan and David

Answer
Hi Susan and David


I swore I answered this and sent it out days ago and here it is again....hoping this did get to you before, but here goes, I will answer again just to be sure you have your answer.

Charlie seems pretty young, so that may be one reason he is having troubles. If he is living with two other rats, you really dont have to worry about him being alone...I am not sure I am following what the problem is unless its important you integrate all the rats in one cage?  

You can continue to expose Charlie to the other rats only during supervision and perhaps when he is older and stronger he can hold his own with the dominant rats.  Keep the cages side by side, only have a piece of cardboard between the cages so tails and paws cant reach each other and get bitten or torn up etc...