Horseshoe Crab Mating Season: And How it Helps our Shore Birds

Dunlins

Photograph taken by: Sam Olweck

Last Tuesday, I was at Tiana Bayside for one of the first times this season. I always like looking down by the water to see what birds are on the shore and capturing photos with my camera. To my surprise, I saw a huge crowd of Dunlins and Ruddy Turnstones. I was excited to see both these species of birds, as I have never seen them on the Long Island shorelines before. 

               When I was done capturing photos of these unfamiliar birds, I went inside our Tiana Bayside facility to do some research.  I came to learn that these species are reliant on the horseshoe crab mating season. During the springtime, thousands of horseshoe crabs will come up on the shore during full and new moons to mate with each other. These incredible mating patterns are part of the reason these living fossils are on our planet to this day. 

 Dunlins are known to be the most widespread shorebirds in the United States, and Ruddy Turnstones are known for their long-distance migrations. They eat the horseshoe crabs' eggs to have enough energy during their travels. This shows that horseshoe crabs are important for more reasons than I previously realized.

Ruddy Turnstones

Photograph taken by: Sam Olweck

I was aware of their impact on humans: we’re reliant on the hemocyanin (copper)  in their blood for medical practices and knew they played a role in various species' food sources such as sea turtles and sharks, but I didn't realize their eggs were such an important food source for our shorebirds. Now when I walk our shorelines this time of year and see these birds, I will know that Dunlins and Ruddy Turnstones are here for fuel, all with help from Horseshoe crabs.

Photograph taken by: Sam Olweck