We have a red sex link hen who is turning 3 this summer that has been acting very tired/lethargic for quite a long time now. I first noticed it during the end of the Fall - she would stand around, often alone, as she didn't seem to want to follow the others, and just stand there, hunched up like she was cold, with her eyes closing, like she is asleep on her feet. She would stand like that for hours. When winter hit, we didn't notice it, mostly because half the hens, including her, would stay in the coop instead of go out into the cold weather. Before, I checked her for a bound egg, for ascites (no distended abdomen or even larger than normal belly), for impacted crop (emptied in the morning), and so on. Everything seemed normal. But she seemed to have no energy. Now that the snow has melted she has made her way back outside during the day, and once again I notice it. She is still standing around, hunched up like she's cold, eyes closed, and makes little to no noise. She eats and drinks, but has no interest in treats, even cracked corn. When I threw some out, every chicken and duck came running, except for her, who remained where she was and stood alone, hunched and uninterested. Again I checked her for the usual. Nothing going on there. She is on the same feed as the rest of our laying hens, and has access at all times to grit. Our hens free-range most of our property and wooded area. I see no sign of mites or lice. I haven't seen any poop with worms in it so far, but we do have a lot of hens. The other sex links in the batch she was in are all acting, eating, and looking normal and healthy. Any ideas? Is there any ideas on what could be wrong with her? I know hybrids don't live as long as the average chicken, but it seems odd behaviour to me, as any chicken we've lost has been sudden and a result of an obvious ailment.