Changewing Island

Changewing Island is a nesting ground and home for the Changewing dragons.

Description
This forested isle hides many surprises in its thick branches — from the acid-spitting, chameleonic Changewings to their iridescent eggs nestled on the boughs. The only safe part of this island is the sky above it, where Changewings are unable to blend into their surroundings. The island is covered in trees, and the Changewings lay their eggs in the branches.

Gem of a Different Color
The forested island had been discovered by Fishlegs Ingerman and his dragon Meatlug. There, they found a "Stone of Good Fortune". However when Fishlegs and his friends decided to return the stone, they realized they were actually dragon eggs. Despite returning the egg, Snotlout Jorgenson and his dragon Hookfang stole four eggs.

We Are Family, Part 1
After Hiccup had been briefly kidnapped by Alvin and the Outcasts

Live and Let Fly
It was revealed to be called Changewing Island. The teens go to Changewing Island to study Changewings as part of Dragon Flight Club. The riders then guided wild Changewings that were released by Alvin back to Changewing Island so they didn't head to Berk.

Free Scauldy
Also, a injured Scauldron was found on Changewing Island.

Night of the Hunters, Part 1
Three years later, the teens went to Changewing Island to search for glowing Changewing acid to light up a new lens they found. They then encountered Tuffwing, a Changewing that Tuffnut managed to capture ot get the Changewing acid. Eventually, they used the acid on Snotlout's helmet to power up the Dragon Eye.