I've just noticed the past few nights when my hens are in the coop ready for bed that my RIR hen and EE hen (both 10 mos. old) frequently shake their heads back and forth quickly like a person might do if you run into a spider web. I've just noticed this when they are in the coop ready for bed. It has been below freezing, so I wondered if they possibly do that to warm themselves although they have some heat including an infrared heat bulb (I've wondered if the red light bothers them because they are the two who are positioned most below the light (the others who are on the same perch are in a darker area). I was really worried when I read some posts about gapeworm since I enjoy digging worms with them (I might re-think that activity), but after I saw videos, I don't think that's it because they aren't gasping for air and seem otherwise fine. The logical culprit would be some type of mites. My hens do have a dust bath area with DE, dirt, sand, and ashes. I can check their heads tomorrow during the day, but I'm not sure if all mites are visible. My other hens, a JG, SLW, and BR haven't been shaking their heads quickly. I'd also like to know in general about health care that should be routine. My vet didn't think I need to vaccinate them since I just have five hens. I have never wormed them or anything because I haven't seen signs of any worms or health problems. I've read some posts about adding ACV to water, which sounds reasonable, but overall there is so much confusing information about basic proactive health care. I have three cats who avoid the chickens, but do pass through their area to get to the back door. We also have wild squirrels and birds in the same areas (near the back deck and door), and I can't control them. I've wondered about cross-contamination. Thanks for reading this.