A remarkable convergence takes place on the Delaware Bay shore each year, a strange intersection of crab, bird and man. Thousands of horseshoe crabs swim up from the dark depths of the ocean to line the beaches and spawn under the light of a full moon at high tide. For one hour, the sand all but disappears as the crabs pile on top of one another making a blanket of horseshoe crabs as far as the eye can see. The spawning on the Delaware Bay shore is the largest in the world. Meanwhile, shorebirds fly from the southernmost tip of South America to the high arctic. They barely stop on their 10,000 mile migration, but make one exception: the dank shores of the Bay where they feed like made on horseshoe crab eggs to fuel their trip. But in the last 20 years, this intricate ecosystem has become threatened and now ornithologists and lay volunteers fly in from around the globe to study, obsessively, the spectacle. The story here is as much about the characters who take weeks out of their lives to come to Delaware each year, as it is about the crabs and birds.

A remarkable convergence takes place on the Delaware Bay shore each year, a strange intersection of crab, bird and man. Thousands of horseshoe crabs swim up from the dark depths of the ocean to line the beaches and spawn under the light of a full moon at high tide. For one hour, the sand all but disappears as the crabs pile on top of one another making a blanket of horseshoe crabs as far as the eye can see. The spawning on the Delaware Bay shore is the largest in the world. Meanwhile, shorebirds fly from the southernmost tip of South America to the high arctic. They barely stop on their 10,000 mile migration, but make one exception: the dank shores of the Bay where they feed like made on horseshoe crab eggs to fuel their trip. But in the last 20 years, this intricate ecosystem has become threatened and now ornithologists and lay volunteers fly in from around the globe to study, obsessively, the spectacle. The story here is as much about the characters who take weeks out of their lives to come to Delaware each year, as it is about the crabs and birds.