The Wearle (Erth Dragons #1) by Chris d'Lacey
The Wearle came to Erth to find out what happened to their previous group, who never returned. Gabrial, a young blue dragon, is desperate to prove his worth. But the dragons aren't alone in the mountains. Down beyond the scorch line, Ren, a young hom boy, is fascinated by the 'skalers'. But when he creeps into their territory, he sneaks out again with a wriggling baby wearling..