I have noticed some of my chickens going the open mouthed gaping yawn thing associated with gape worm. I have seen them do it when they are stressed, but now they are doing it while they are just out in the coop chilling. What do I check for when I look in their throats? I didn't see anything when I checked in my pullet's throat. How do you treat it? I have 7 chickens outside right now, they are between 6 weeks and 9 months.