Is there a way to determine how old a ferret is?

He is totally cute by the way. A vet would be the best person to tell the age. I have four ferrets, on is jet black, but during the winter he goes completely gray, so it may not be a age thing. Also they lay flat on the ground to hide....Its there way of playing with other ferrets or even their owners. If he is around the 3-5 pound range then he is definitely an adult. Hope this helps