I have read on this forum that chickens are 'dusty'. My first ever chicks are now 4 weeks old, and in the last week I've noticed a build up of dust in the coop. It began before I started letting them out in the run for a while on warm days (which they love), so it's not just the dust from outside. I'm using pine pellets for the bedding, and it doesn't seem inherently dusty (even though it's compressed saw dust!). It is a very fine powdery dust. Anyone know what this is? Is it coming from the chickens? Dead skin flaking off or something? Just curious.