Animals on Atamara are moving south, which appears to be the same direction as they're moving on BT. In both cases, they're moving away from the icy, snow covered, northern regions. So something is coming out of the polar ice cap? Eternal winter and the big freeze?
Not sure how that factors into the directions of migration on other islands, but since the messages (on all islands?) mention seasonal migration of animals, it seems that they're all moving away from the colder regions of the maps towards the warmer, more summerly, regions.
Interesting stuff.