Well I just hit Tier 3, and so far it's mostly still espers. Abandoned towns, grasslands, deserts, snow. Well, maybe I get them about 70%. I get the occasional robots, bats, eagles in forest areas, rhinos and grasslands, but the majority is still espers. I guess I'm just taking too long to advance, I get too sidetracked exploring. Maybe I should just go and finish this continent already? I'm already max upgraded and my spells are adequate.