Pets & Horses Regional Heightmaps for Flying Mounts

Firstly, let me say the Wyverns are so so cool. But one thing I've noticed when flying over the ocean is that they tend to scan for the lowermost solid block to determine their maximum altitude, maybe this won't be so bad once I figure out breeding but right now it tends to have random drops where I fall into the water in the middle of nowhere.
It also doesn't make sense that they'd be limited by height in the canyons they're supposedly native to. The height scanning makes it so you've got quite the bumpy ride there.