Percentages: Feeding the Nutcracker

The Clark's Nutcracker uses its remarkable memory to store pine nuts for winter survival. Each autumn, it hides up to 30,000 nuts across Yellowstone, ensuring it has enough food despite a 70% retrieval success rate. The unrecovered nuts grow into new pine trees, supporting future generations of nutcrackers.

Why does the Clark's Nutcracker bury more nuts than it actually needs?

What happens to the nuts that the Clark's Nutcracker does not recover?