The thing that you need to be worrying about for missions (like moving north) is your ratio of leaders/huts -- if you don't have a high enough ratio, then you won't be able to succeed. The game guide is somewhat lacking in some of the ratios, namely those that you need for species-specific missions and moving north/south.
You need to have a 90:1 leader to hut ratio to be able to successfully move.
You need to have a 90:1 leader to hut ratio to be able to successfully move.