I've only seen it when my population is maxed out, around 90.

I agree with Arnie. I too have seen this event only when the population is at the max!

Yeppers I got it a max population too.

ya it happens only in max pop i think so u can have more people cause it only takes adults

I had that event 8 villagers leaving on a raft going back to the south shore or words to that effect when my popurlation was less than 115 and 90