Brd709 There's not any connection that I know of. Chickens came with Cottage Living which was after Island Living. So, it's not a part of any Island Living activities, etc. I was thinking that if you were in the Sulani zone that has the bar, that you might be just seeing one of the wild chickens that are there as an environmental effect. But since you're playing in Newcrest, that's not it since those chickens are only in that one Sulani zone. You can't grab them either.
Can you grab the chicken on your lot in build mode? If you can, that's a sure sign that it's one of those from Cottage Living. And if it is, I have no idea why or how it showed up on your lot. It is a bit odd that it happened though. I haven't ever seen one in my game that randomly generated. I've only seen those that I bought and placed on one of my lots with a coop.
Hope this helps.