Steeper and higher than mere hills, mountains are over 1,900 feet in elevation and typically have steep, sloping sides and rounded ridges and peaks. They tend to be rocky and barren above the tree line, and many mountains get significant amounts of snow in the winter months. They are formed when the Earth’s tectonic plates collide, pushing the crust of the planet higher, forming mountain ranges.

What all islands have in common is that they are isolated from the mainland. That creates a unique environment, with species of animals and plants that may be very different from their counterparts on the mainland. Island ecosystems are fragile and easily disturbed by the combined threats of introduced species and diseases, habitat loss, and the cascading impacts of climate change. While islands make up a small amount of Earth’s land mass, they are disproportionately vulnerable to biodiversity loss.