Very - it's a whole new world for them and being prey animal's they are extra nervous animals so will take them some time to come round.
You probably won't see much of them as they will be waiting till you aren't looking to get food etc, make sure they have plenty of access to food and give them a few days to settle in, then begin talking to them and offering them tasty treats from your hand it's a long process and takes guinea pig's quite a long time to come round.
Patience is your best friend right now but it is so rewarding when you win over there trust.
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