I’m sorry for your loss. 🙁 I’ve been in your situation before, it’s tough. It’s really your call as to when to start trying to bond her again. I’ve found that my buns that have lost their partners usually benefited from me bringing home another bunny relatively quickly, but you also don’t need to rush out and get another rabbit as long as Kira doesn’t seem super depressed. If she is eating and pooping normally, it’s normal for her to be a bit more “quiet”.
I think you could try bonding her with any neutered male, age doesn’t matter too much. Personality matters more, so I would talk to the shelter/rescue staff to see if they have any insights on buns that might be a good match (such as a bun that was previously bonded or seems to like other buns). The bonding process is the same as any other bond, you just want to be more aware of stress levels and take things slowly.
Does the shelter have a foster to adopt option? That could be a good way to trial a bunny.
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The answers provided in this discussion are for general guideline purposes only. The information is not intended to diagnose or treat your pet. Seek the advice of your veterinarian or a qualified behaviorist.