feather loss normal?

[peartreehens]

So my girls are 10-12 weeks old. Is it normal for them to lose some longish, non-down feathers? In the last week, I've found about a dozen 5-6" long feathers in their (100 sq foot) run. I have 8 birds, 6 different breeds. Clearly the feathers aren't just from one bird, and their origins seem to be fairly evenly distributed among the girls (buff orp, barred rock, welsummers, EEs, BSL, etc, pretty easy to distinguish whose are whose). I have never seen them pull feathers (or even peck at each other--or at least not for the last 8 weeks, since they've all been introduced). Any thoughts?
thanks!

 

[Ridgerunner]

Juvenile molt. Chicks go through two molts before they grow their adult feathers. They just outgrow their baby feathers and need to replace them. They probably went through another juvenile molt at 8 or 9 weeks.