This could be common to an extent. But constantly doing this, for months on end with other symptoms is not normal. We ended up putting my hen down, she wasn’t laying, she wasn’t eating, she would hardly drink, she wasn’t active. It was sad. Something was clearly wrong and for the life of me...
I’m not saying this will be your hen… but I had a hen who did this for a few months. She was progressively getting ill, though. It started with sneezing, then it was coughing etc… the opening mouth (with no sound) thing all the time! She eventually stopped eating. She became pale over time, had...