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Thursday, June 20, 2024


Red Knot Numbers See an Increase This Year

Shown is a file photo of red knots on a Delaware Bay beach.
Tom Haggerty/File Photo

Shown is a file photo of red knots on a Delaware Bay beach.

By Karen Knight

COURT HOUSE – Restorative efforts along the Delaware Bay to protect the ecosystem seem to be paying off, as studies indicate the number of red knots stopping to feed on horseshoe crab eggs are up this spring.  

However, one biologist cautions that global warming and the continued killing of horseshoe crabs for their blood and as bait is an area of concern. 

Dr. Larry Niles, of Wildlife Restoration Partnerships, has spent years studying the migratory red knots, horseshoe crabs, and the Delaware Bay ecosystem.  

He said, “The timing of the temperature of the bay at the beginning of May was good for the spawning of the horseshoe crabs all month. In total, this was an average year for the return of the red knots, but it was a good year for the birds because they returned after a couple of years.” 

Niles said the birds are counted by staff from Great Britain, Australia, New Zealand, and the U.S. on the ground, in the air, from boats, and statistically by satellite tags.  

This year, they believe 22,000 birds stopped in the Delaware Bay area to feed on their voyage from South America to the Artic. This is up from 12,000 in 2022 and 6,000 the year before that.  

However, this year is still below the 30,000 counted in 2020.  

“The birds are coming from South America, Florida, and the Caribbean, and when they arrive in the Delaware Bay region, they need to double their weight to continue on their journey,” Niles explained. “In 2019, we had a cold spring, and the water never got to the threshold we need (59 degrees Fahrenheit) until the end of May. By that time, a lot of birds had already left because there were no eggs. In 2020, 6,000 didn’t come back.” 

“We reached a plateau in 2022 because, despite a spike in the crabs able to spawn, the horseshoe crab is still over-harvested,” he added. “I think the higher numbers are indicative of all the birds in the Atlantic Flyway. We had one bird with a satellite tag that stopped in South Carolina as there are crabs there as well. The bird fed and started its trip to the Artic. It hit opposing winds, so it turned around and came back to the Delaware Bay, 700 miles. It fed a couple of days before taking off again. We probably wouldn’t have caught it during our visual count, but it’s part of our statistical count.” 

Niles said there is some evidence of climate change slowing down the Gulf Stream, which typically brings warmer water and temperatures.  

“If the gulf stream slows, it would mean our spring would be cooler,” he said, “but it seems our springs are a bit warmer.” 

Almost all the red knots stopped in New Jersey, according to Niles, who said the state’s bay management program is very “strong,” whereas Delaware’s “does practically nothing.” 

“I am optimistic because our efforts to protect the beaches, building reefs, having our stewards flip over crabs and protecting the birding areas, they seem to be paying off with the return of the red knots,” he said. “But the killing of crabs for the blood industry is increasing with almost no surveillance, no reporting, no information provided to the public.  

“The government agencies say the crab can be used as bait, which essentially means they are not worth anything,” he continued. “But then they allow a $500 million blood industry that is depleting the crabs. Are the crabs worth something or not? They are leaving the ecosystem depleted, decimating the recreational fishing industry.” 

A protein in the horseshoe crab blood is used by pharmaceutical and medical device manufacturers to test their products for the presence of endotoxins, bacterial substances that can cause fevers and even be fatal to humans.  

Contact the author, Karen Knight, at 

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