Me and my girlfriend have a two year old male chinchilla named SumSum (standard grey), and recently we bought another male who is 7-8 months old named Jacob(violet).

We heard when introducing them take it slow, we placed cages next to each other for a month, there was quite a bit of agressive behaviour and noise in the first week or two, but after that calmed down we started to do joint free runs in the hallway.

At first they mostly stayed away from each other, and when they got close I would place my hands inbetween them so they wouldn't be able to damage each other, after about a week of this, me and my girlfriend started to let them have more freedom with each other.

This leads us up to the last few days. All they have done today and yesterday on the free runs (they've had about 4 hours) is basically wrestle to get onto each others back. They will approach each other head on and their heads will go side by side as they spin round trying to get ontop of the other one. Kind of like a ying yang symbol. Sumsum the older chin is bigger and stronger and therefore 9 times out of 10 gets on top where he will groom Jacob, or just hold on, sometimes ejaculating onto jacobs back (eww messy). They haven't hurt each other and don't seem to be scared or anything. Is this normal bonding behaviour? Any ideas on how long until they stop being obsessed with mounting one another and just cuddle or groom? I feel they are comfortable with each other around, as today they both went to sleep quite close to each other after twenty minutes of wrestling.

As for the sounds they make, Jacob is often silent, while Sumsum will walk around softly squeaking while wagging his tail after a successful mount.

Here are some pictures of Sumsum, pictures of Jacob are all still on my phone at the moment.

Having a treat on my bed


Sleeping with my girlfriend when he was a baby


A hard day


Saying "hello"

awwww bless he looks like a content little nilla

it sounds like you have gotr as far as you can with "playtimes" the mounting behaviour wont stop till they are together fully, the next step is to get them together, you need to pick a time when you are going to be around for a few days, just encase.
after their playtime, get a pet carrier out (neutral territory) and pop them both into that, you can carry that around with you and keep an eye on them, for a few hours, if you are happy that they arent kicking off, then you need to choose which cage they are going to go into, you need to thoroughly disinfect the cage to remove any scent of the origanal inhabitant, anything you cant bleach (including toys) you need to bin

once the cage is clean and dry, rearange it, so it looks different to the origanal inhabitant, maybe move it to a different place if you can too, pop both chins into the cage, put the one who didnt origanaly live in that cage in first, and then you need to sit and watch for a few more hours, when you are sure they are settled you can just poke your nose in every hourish to make sure things are still ok

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