duhns they can despawn. not in all cases but its definately possible they can. maybe in the occasion that your sheep didnt despawn, that someone had been around every once in a while to update the chunk without knowing it

Every time I go to the dance floor, all the chicks despawn as well!

Is this some sort of bug? I texted a pe to the bartender, but he has no clue.

I might have to download some new dansmoves.

I agree with Dunsjohn. No passive mobs will ever despawn except because of some glitch or plugin update. A few weeks ago I was exploring near my castle (private warp) which I hadn't visited for several weeks, and about 400 blocks south of my castle there was still a sheep that I'd shorn several weeks before that. However, my farm lost all it's animals over night a few weeks ago, and everyone else on the server had the same problem. I put in a petition to get them back and it cas closed saying 'no animal refunds'

I have this problem as well. I have a bakery that RELIES on chickens, and this is really starting to hurt it.

Ahhhhh :'D Classic belgian trollage