I was reading posts about chickens that mourned the loss of a flock mate and they sometimes never recovered.I know not all animals have the same level of emotions as humans but they definitely understand more then we give them credit for.
I've read posts claiming a chicken changed its sex. Being published on the internet doesn't make it true.
My dinosaurs aren't stupid, but sorrow and remorse do not appear to be part of their emotional lexicon. From an evolutionary standpoint, that's likely to their benefit. Even when I seperate chicks at 8 weeks +/- from the grow out pen and integrate them into the main flock, they only hang out at the fence between the grow out run and the free range pasture for a day or two - and that seems more an effort at finding safety than any sorrow for their now separated flock mates. Certainly, their prior flock mates don't seem to care.
No, we'll never "know", but I'm confident in their predicted behaviors after much observation, and they don't behave like they are mourning. ...Which is all that matters to me.