Criterion (ix): The Wrangel Island Reserve is a self-contained island ecosystem and there is ample evidence that it has undergone a long evolutionary process uninterrupted by the glaciation that swept most other parts of the Arctic during the Quaternary period. Criterion (x): The Wrangel Island Reserve has the highest level of biodiversity in the high Arctic. Wrangel Island boasts the largest population of Pacific walrus with up to 100,000 animals congregating at any given time at one of the island’s important coastal rookeries. Since Wrangel Island contains a high diversity of habitats and climates and conditions vary considerably from one location to another, total reproductive failure of a species in any given year is practically unheard of. Given the relatively small size of the area, this is very unusual in the high Arctic.