Like squirrels gathering nuts for the winter, the small foxes hoard bird eggs in case there's not enough of their favorite prey—the collard lemming—to go around in the spring.

The stored eggs can last for up to a year after being buried, thanks to the Arctic permafrost and natural preservatives inside the eggs.

"It appears as if cached eggs are used as a backup for unpredictable changes in lemming numbers," lead study author Gustaf Samelius of Grimsö Wildlife Research Station in Riddarhyttan, Sweden, said in an email.

"This is a neat adaptation in an environment where food abundance changes dramatically both among seasons and years."

Samelius added that the study is the first to show the extent to which the carnivores can depend on