At Delaware Bay, migrating red knots feed heavily on the eggs of which animal?

At Delaware Bay, migrating red knots feed heavily on horseshoe crab eggs.

Red knots arrive at Delaware Bay each spring during one of the most demanding stages of their migration from South America to Arctic breeding grounds. Their timing closely matches the annual spawning of Atlantic horseshoe crabs, which bury or scatter huge numbers of eggs in the bay’s beaches and intertidal sediments.

The eggs are an exceptionally valuable refuelling food: they are plentiful, easy for the birds to digest and rich enough to help red knots rapidly rebuild fat reserves. That stored energy is essential for the final journey north and for breeding after arrival. Red knots probe shallow mud and beaches with their bills, swallowing eggs and other small prey.

The relationship has also exposed a conservation problem. Horseshoe crabs are harvested for bait and biomedical uses, and reduced spawning can mean fewer eggs for birds. Declining food supplies have contributed to serious pressure on some red knot populations. The birds do eat molluscs and crustaceans elsewhere, but Delaware Bay is especially associated with horseshoe crab eggs.