All five of my babies (2 fawn and white crested runners, 1 black runner, 1 black crested runner and 1 khaki campbell) now 3 weeks old have this funny pea size tuft of fir at the base of the tail on thier back...I found it on the fawn and white runner (still yellow but getting white feathers in) and it is bright yellow and super soft but very dense. I then snatched each baby and low and behold they all have it in differing colors. Why is this? Anyone know?! Its the funniest thing!