User blog comment:Lord Loss/Monster Hunter Theory... Blog/@comment-5460283-20120916162115/@comment-1685631-20120917032929

Uragaan is a volcanic species that eats rocks, there's no reason for it to migrate at all. Diablos would have a hard time digging, it's true. And I'm pretty sure it always travels by digging; why go through all the extra effort just to walk to some island with no cacti (flying isn't really an option, just look at it)? And that's not mud on the coastlines, that's sand.

Face it, we have to chalk this one up to Capcom making no ecological sense.