I have 12 chicks in a large brooder on my front porch. They are 5 weeks old as of yesterday, 5/8/16. I was visiting with them and checking on them a little while ago and I noticed several, if not all, of them are shaking their heads... not super hard or for very long, but like a dog much shake it's head if you blow on it's ears. My first concern was lice/mites or some other little bug. I didn't get any out to inspect them closely at that time. They are in a brooder that 2 older groups have already occupied with no signs of lice or mites. Any opinions?