Females can change a lot due to hormones too. Sometimes breeding will increase the lightening of their "black" parts.
My Ben went through a period where the hair on top of his head turned very silver (maybe 6 months to a year old), but it is now back to gold/tan, but lighter than his beard. I just went through some of his pictures and his coloring seems like it changes ever 6 months or so. I was having trouble uploading them and finally gave up. |