User blog comment:BannedLagiacrus/Discussion of the Week: Nomadic/Migrational Species/@comment-25119729-20150118110420/@comment-6050823-20150118133200

I actually included Barroth because it well migrates there for a reason. Barroth will migrate to the Deserted Island when there are particularly long droughts in the Sandy Plains dry up their favored bogs and watering holes. Some of the other monsters not usually seen in the Deserted Island do have some explanation as to why they appear in the Deserted Island, not all of them.