A red knot tagged for research rests and refuels in Mispillion Harbor, Delaware. Climate changes such as sea-level rise and increasing storm intensity are adding challenges to red knot survival. Photo: Gregory Breese/USFWS.
More photos: Delaware Bay Estuary Project photoset on Flickr
Not far from the casinos of Atlantic City, a different kind of wager takes place each May along the shores of Delaware Bay.
That’s when red knots, birds the size of a coffee mug, stake their future on the eggs laid by tens of thousands of horseshoe crabs. Without enough crab eggs to fuel them, the long-distance fliers may not survive their 10,000-mile spring trek from the southern tip of South America to their Arctic breeding grounds.
In recent years, the red knots’ bet on the crab eggs has been more of a crapshoot. First, the over-harvesting of horseshoe crabs for bait caused an egg shortage. Now, scientists also point to a wild card.
“The peak of horseshoe crabs spawning in Delaware Bay has not always been aligned with the migration of the red knots,” said Gregory Breese, the U.S. Fish and Wildlife Service’s project leader for the Delaware Bay Estuary Project. “That could be related to climate change.”
Changing water temperatures in Delaware Bay and more frequent and intense storms appear to be disrupting the synchronization between the spawning of the crabs and the arrival of the red knots. When waters warm, the crabs lay their eggs earlier, and other creatures may beat red knots to the feast.