Tie-dye optional at the festival. Starts at noon.

Mispillion Harbor Reserve, a wildlife area north of Slaughter Beach, plays a big role in the lives of shorebirds and horseshoe crabs.

Saturday, May 18, Mispillion Harbor Reserve’s DuPont Nature Center will host the tenth Peace, Love and Horseshoe Crab Festival from 12 to 3 p.m. It celebrates the reserve and its importance to wildlife. Horseshoe crabs are vital to the existence of not only shorebirds, but humans too. The biomedical industry uses horseshoe crab blood to test vaccines and medical devices for harmful bacteria.

The festival has activities for children and families, including eco-stations, wildlife displays, food trucks and vendors. Delaware Shorebird Project biologists will be on hand on the deck with scopes for shorebird viewing.

Mispillion Harbor Reserve is part of the larger Milford Neck Wildlife Area. The reserve and DuPont Nature Center are owned by the state and managed by the Department of Natural Resources and Environmental Control.

Unlike most other state wildlife areas, access is strictly limited because its shorelines and tidal marshes are so important to spawning horseshoe crabs and migratory shorebirds.

“The horseshoe crabs visit the harbor each spring and will come up onto the harbor’s gently sloping beaches to lay their eggs,” nature center manager Lynne Pusey said. “The shorebirds show up around the same time and will eat the protein-packed horseshoe crab eggs to fuel their journey from South America to the Canadian arctic.”

Common shorebirds passing through include endangered red knots, ruddy turnstones, dunlin, sanderlings, semipalmated sandpipers and semipalmated plovers. Common bird species found in the harbor include American oystercatchers, great blue herons, bald eagles and osprey.

Tens of thousands of horseshoe crabs are estimated to visit the reserve annually to spawn, due to its particularly attractive conditions.

Those conditions include a jetty that protects the harbor, reducing the effect of waves and making the waters a little calmer than the surrounding coastal sites. In addition, the harbor itself is fairly shallow, so the water quickly warms to horseshoe crabs’ preferred spring temperature of 59 degrees.