This summer NYC Bird Alliance reached a milestone—10 years of Horseshoe Crab spawning surveys in Jamaica Bay! During the full and new moons in May and June, NYC Bird Alliance conservation staff and dedicated volunteers ventured out at night to count and tag spawning Horseshoe Crabs, a critical food source for shorebirds like the threatened Red Knot. Nearly 200 community scientists braved the unpredictable weather and late nights to help with monitoring at Jamaica Bay this year, including groups from Patagonia, the Metropolitan Society of Natural Historians, P.S. 9 Teunis G Bergen, and the Trinity School. Our Horseshoe Crab monitoring and tagging efforts are part of a larger project run by the New York State Department of Environmental Conservation and Cornell University Cooperative Extension.   

Our preliminary results indicate Horseshoe Crab numbers are remaining stable in Jamaica Bay. Overall spawning peaked around the full moon on May 29. Spawning activity numbers at Big Egg Marsh this year were more than double the area’s 2017 numbers, making it this year’s most active beach. Big Egg Marsh also peaked slightly earlier than the other beaches, with 326 crabs in our quadrat sampling on May 17. On June 28, despite adult crabs being scarce, Big Egg Marsh volunteers reported thousands of tiny, newly hatched Horseshoe Crabs in the surf.

Spawning activity declined slightly at Plumb Beach East and West. Plumb Beach East had a peak 185 crabs in quadrat sampling on May 29, while Plumb West had a high count of 30 crabs in quadrats on May 31. Dead Horse Bay’s numbers were the highest they have been in four years, with 2,200 total crabs found on the beach on the night of May 31. Dead Horse Bay is a “full count” where we count every crab on the beach instead of taking quadrat samples, so it took volunteers until 12:30am to count them all!

We were also able to tag 800 Horseshoe Crabs this year, bringing the total number of crabs tagged throughout the program’s 10-year history to 5,980! Of those 800, 82 crabs were resighted later in the season at the same beach. We also spotted 11 crabs that had been tagged in Jamaica Bay by NYC Bird Alliance in previous years; six of these were tagged in 2017, two in 2016, and three in 2015. Six crabs were spotted at Jamaica Bay that had been tagged elsewhere: Fire Island, Long Island, in 2012; Breezy Point, Queens, in 2012; Pikes Beach, Long Island, in 2015; Pikes Beach, Long Island, in 2016; and two from Calvert Vaux Park, Brooklyn, in 2017. These tag resightings help us learn about the importance of Jamaica Bay to the overall New York State Horseshoe Crab population.

This important work would not be possible without the dedication of our site coordinators Andy Martin, Christine Nealy, Ann Seligman, and Dottie Werkmeister. We also thank Patagonia, The U.S. Fish and Wildlife Service Neotropical Migratory Bird Conservation Act grant program, National Park Service, Elizabeth Woods and Charles Denholm, and NYC Parks for their support of this year’s monitoring.

-Kaitlyn Parkins, Conservation Biologist