Sitting at the mouth of the Mahon River along the central shoreline of the Delaware Bay, the beaches, saltmarshes and tidal creeks of Port Mahon provide a unique mosaic of habitats. The preserve hosts a rich diversity of bird life. In the spring, millions of migratory birds stop to rest and refuel in Delaware Bayshores just as the world's largest population of horseshoe crabs begins spawning on the beaches. Horseshoe crab eggs provide the critical nutrition that shorebirds need to continue the journey to their arctic breeding grounds. The landscape of Port Mahon also provides a temporary or permanent home for numerous species of geese, duck, fish and amphibians.