Yep, the female Budgie with a blue cere that has white rings around each nostril is what confuses more people than anything else when sexing a Budgie!!! Outlawed Spirit got it! When a female Budgie goes into Breeding-Season their ceres turn a very dark brown color and become really thick and crusty. And then when they come out of Breeding-Season they turn back to their original color, which is either white/cream, tan, brown, or blue with white rings around the nostrils...Males have either solid blue, solid pink, or solid purple ceres and they never change again after puberty.