ALBANY, N.Y. — When red knots descend on the beaches of Delaware Bay this spring famished from their marathon flight toward the Canadian Arctic from the tip of South America, the rosy-breasted shorebirds may find slim pickings instead of the feast of horseshoe crab eggs they count on to fuel the rest of their migration.

Hurricane Sandy scrubbed away almost all the sand the crabs need to spawn upon. Restoring it in time is a top priority of wildlife groups beginning to repair Sandy’s massive damage to dunes, beaches and salt marshes along the Eastern Seaboard that support a diverse population of birds, fish, marine organisms and other wildlife.