One of my rats just had a litter last night but it only had 4 of them in there. 3 were in a pile like normal and one was in the corner, it looked neglected and it was kinda cold. I put that one back in the pile but I haven't been home yet.

This is like the 7th or 8th litter from this one rat and they have always been around 9. Just seems weird to have only 4. Is this normal?