Horseshoe Crab Monitoring 2023 Season Recap

Volunteers document a recently tagged Horseshoe Crab at Plumb Beach East. Photo: NYC Bird Alliance

Katherine Chen | August 7, 2023

For nearly 15 years, NYC Bird Alliance has been organizing a special opportunity for community scientists of all ages and backgrounds to come out to the beaches of Jamaica Bay in May and June on 12 nights around the full and new moon.

The purpose of this activity? To monitor and tag Atlantic Horseshoe Crabs. During these special nights, thousands of horseshoe crabs come ashore along Plumb Beach and Big Egg Marsh in Jamaica Bay to spawn. A single female can lay over 100,000 eggs in a single season!

And why do we care so much about these horseshoe crabs and their mating habits? Well, it is an amazing spectacle to see so many horseshoe crabs—a species that actually dates back to prehistoric times—populate our city beaches in droves on these nights. But more importantly, from a conservation perspective, the million-plus eggs laid by horseshoe crabs provide a critical food source for migrating shorebirds, which fly through our area at exactly the same time as horseshoe crab spawning season.

Red Knots and Horseshoe Crabs at Jamaica Bay. Photo: Don Riepe

Horseshoe Crabs Eggs Are a Critical Food Source for Shorebirds

Without these horseshoe crab eggs to feed on, many shorebirds, including the threatened Rufa Red Knot, would not have enough fuel for their incredibly long journeys, which can be as far as 9,300 miles each spring and fall between wintering grounds in Tierra del Fuego and nesting territory above the Arctic Circle.

It’s not just the Red Knot that is of concern: most of our North American shorebird species have suffered marked population declines in the past 50 years. These declines may be due to multiple factors including habitat loss, environmental contaminants, and over-harvesting of shorebird food sources like horseshoe crabs.

To make sure there are enough horseshoe crabs coming to our beaches and providing enough food for our grateful shorebirds on tight “energy budgets,” NYC Bird Alliance enlists hundreds of volunteers to flock to our beaches, clipboards in hand, to count how many crabs are coming to our shore each year. This is part of a statewide project led by Cornell Cooperative Extension of Suffolk County in partnership with the New York State Department of Environmental Conservation.

A volunteer holds up a Horseshoe Crab for documentation. Photo: Bianca Otero

Horseshoe Crab Monitoring and Tagging Numbers at Jamaica Bay This Year

It was a fantastic season of horseshoe crab monitoring! We counted 2,579 horseshoe crabs during the 2023 season, 1,842 male and 737 female. This is approximately 700 more than what was counted last year. Due to the count method employed, some of the horseshoe crabs may have been counted multiple times; nonetheless, this is an encouraging number and shows populations were stable this year. And it seemed to be a productive mating season as well: we saw several cavities in the sand with thousands of eggs each. It was a good year of feasting for shorebirds.

In addition, we tagged 623 horseshoe crabs. By tracking their movements with tags, we gain valuable insights into their behavior and migration patterns. Furthermore, these findings help identify beaches in need of protection and conservation efforts. Last but not least, we recovered and reported several tags, including some from previous years like the one spotted on May 21 that was originally tagged in 2016 at Raritan Bay, NJ.

Horseshoe Crab Monitors walk along the beach at Jamaica Bay. Photo: Bianca Otero

Other Highlights from Our Monitoring Season

Our Horseshoe Crab Monitoring program always provides a memorable experience for volunteers. It is really cool to be out on these beaches during nightfall! This year, in addition to all the great sunsets volunteers always get to see, we got to witness the beautiful Strawberry Moon on June 3.

We had a heartwarming story too! A site coordinator lost their thermometer, only to be reunited with it after an amazing volunteer spotted it on the beach with their eagle eyes. Gestures like these demonstrate the incredible commitment and care our volunteers bring to the program and each other. Most of all, we were incredibly lucky to have hundreds of volunteers joining us on the beaches this year, including many budding scientists!

It was a truly outstanding year, with many new and returning faces. We send a huge thank you to our wonderful site coordinators: Ann Seligman, Nancy Liang, and Dottie Werkmeister! And of course, a big thank you to all of our volunteers. We cannot stress how important our volunteers’ contributions are: without you, this work, as well as other community science initiatives like our Project Safe Flight collision monitoring, would not be possible. Thanks again and we look forward to seeing community scientists again on our beaches next year.

Red Knots and Laughing Gulls with Horseshoe Crabs at New Jersey Beach. Photo: milehightraveler / Getty Signature Images

Other Opportunities to See Horseshoe Crabs and Shorebirds

We monitor horseshoe crabs every year and would love for you to join us again in 2024. Please keep an eye on the NYC Bird Alliance website for the call for horseshoe crab monitors in March/April 2024.

You can also subscribe to our eGret newsletter to receive email notifications about upcoming volunteer opportunities throughout the year. Or follow us on Instagram and Twitter.

Want to see the birds that rely so heavily on these horseshoe crabs for food? We invite you to witness the great spectacle of shorebird migration in our city at the 18th Annual Shorebird Festival at Jamaica Bay on August 19. There will be free and fun activities throughout the day, in partnership with the American Littoral Society, Jamaica-Bay Rockaway Parks Conservancy, and Gateway National Park Service! Learn more on American Littoral Society's webpage here