Carrying its trophy from a raid on a snow goose nest, an Arctic fox heads for a suitable burial spot. This is June and bonanza time for the foxes of Wrangel Island in the Russian Far East. Lemmings are the basic diet for Arctic foxes, but Wrangel suffers long, harsh winters and is icebound for much of the year, making it a permanent source of stored food for these opportunist animals. The food convoys arrive at the end of May. Over just a few days, vast flocks of snow geese descend on the tundra of this remote UNESCO World Heritage Site, traveling from wintering grounds some 4,800 kilometers (3,000 miles) away in British Columbia and California. Not only is this the biggest breeding colony of snow geese in the world, and the only remaining one in Asia, but it is also growing: from 160,000 geese in 2011 to about 300,000 by 2016. The Arctic foxes catch any weak or sick birds, but what they feast on are the goose eggs, laid in early June in open nests on the tundra. Though the pairs of snow geese actively defend their nests, a fox may still manage to steal up to 40 eggs a day, harassing the geese until there’s a chance to nip in and grab an egg. Most of the eggs are then cached, buried in shallow holes in the tundra, where the soil stays as cold as a refrigerator. These eggs will remain edible long after the brief Arctic summer is over and the geese have migrated south again. And when the new generation of young foxes begins to explore, they too will benefit from the hidden treasures.