The GCA 2009 Pictorial Review

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The scene along the New Jersey side of Delaware Bay, north of the tip of the Cape May Peninsula: typically four or five species of migrating shorebirds, all feeding on Horseshoe Crab (Limulus polyphemus) eggs on the shore (at Cook's Beach) and in the shallow water of the advancing tide. Three of our team – (left to right) John Patrick Brown, Porter Turnbull and Norman Famous.
Before and after digging up the sand in furrows at right angles to the advancing tide line to reveal Horseshoe Crab eggs laid 4-9 inches deep.
Shorebirds at rest – Ruddy Turnstones, two Sanderlings and Semi-palmated Sandpipers. Shoulder to shoulder Red Knots feeding at Moore's Beach at the mouth of a tidal estuary system emptying into Delaware Bay.
Horseshoe Crabs mating and burying eggs under the sand. Disturbance to the Horseshoe Crab nests by subsequent egg laying crabs exposes a myriad of eggs on the sand and in the water. Horseshoe Crab (Limulus) eggs left on the beach by the outgoing tide.
Retrieving a test plot corner marker after the tide has flooded.

Storing samples in Ziplocks for four corners of a plot.
Porter raking test holes, then taking measured samples of sand containing Limulus eggs, which will be counted, recorded and statistically analyzed

Laughing Gulls are the principal avian competitors of shorebirds for the crab egg harvest. These are shown within our test plot groups. When we provided an alternative fish-based food on beach locations separate from the ones with natural supplies of Limulus eggs, the Laughing Gulls took over the provisioned areas and ate the food in a dense pack until all the alternate food was gone.
Researchers at Delaware Bay have found that many shorebirds feeding on Horseshoe Crab eggs are leaving on their flights to the Arctic underweight, which threatens their own survival and the chance of successfully rearing young. Here is a trapped Red Knot just before release by researchers, this one part of a population monitoring study conducted by Larry Niles and co-workers. Red Knots, a Ruddy Turnstone and one Semi-palmated Sandpiper flying to an active feeding beach.

Thank you for reviewing our 2009 season!

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