The crabs are back! And so are the birds! It’s mating season for Delaware Bay’s infamous horseshoe crabs–those ocean-dwelling, prehistoric-looking creatures that come ashore each May and June to lay countless numbers of eggs on the sand. Timed to coincide perfectly with this mating frenzy is the annual arrival of globe trotting shore birds, such as red knots, ruddy turnstones and dunlins, who come to feast on the eggs. WHYY’s health and science desk was out with members of the Delaware Shorebird Project this week, a team of biologists and international volunteers who capture, tag and survey birds. Their data help to monitor the populations of these long distance travelers. Red knots, for instance, fly up from Tierra del Fuego and stop in Delaware and New Jersey on their way to their nesting grounds in the Arctic. In fact, we spotted a bird that wore an orange-colored leg band–an indication that the bird had been banded in Argentina. The Delaware Bay is a critical layover for the birds’ flight to the Arctic. They arrive here emaciated from their long flight, but the great abundance of horseshoe crab eggs allows the birds to replenish their fat stores. A decade or two ago horseshoe crab numbers dropped. That translated into fewer eggs, causing shore bird numbers to drop in turn. WHYY is following biologists as they try to determine whether conservation efforts have helped the bird populations stabilize or even rebound. Stay tuned for more updates as we continue our reporting.