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We surveyed the bay again on May 26, 2023, finding almost the same number of red knots as in our first count, 21347 knots. We saw 12,466 Ruddy Turnstones in NJ in this count, and with the 11103 Ruddys seen by the Delaware ground counters, the total knots exceed those seen in 2019 and are much higher than those seen in 2020-2022. These are the final numbers for the season so we can rest easy that the 2023 Shorebird stopover on Delaware Bay was a success.
I’m using the ground and boat count numbers collected by both NJ and DE Shorebird Project Teams because the NJ Fish and Wildlife aerial count conducted by new observers was half the number of knots seen in NJ’s ground and boat counts.
We found the number of shorebirds drastically reduced during a ground count of the best areas conducted yesterday (May 29,2023). At East Point, where we saw 8000 knots two days ago, we found only 200. We saw just over 100 knots at Moores yesterday. We saw 7000 knots there only a few days ago. Very few knots were seen on the beaches South of Reeds Beach yesterday. So for all intents and purposes, most of our Arctic nesting shorebirds have left for the Arctic.
But Humphrey and I will conduct a final boat count today.
The number of red knots and turnstones in NJ this year gave our team a much-needed boost. The birds came back! But hidden in these numbers are a few thorny questions. Where did they go after declining from over 30,000 in 2019 to 6000 in 2021? We know the reason. They came in 2020 and found no horseshoe crab eggs, so they didn’t come the next year and only partially in 2022. The same thing happened in 2003 when crabs failed to spawn. But where did they go? We heard reports of birds bypassing the bay for Atlantic Coast habitats. Still, these were probably birds wintering in Florida or the Caribbean and not needing the fast weight gains afforded by horseshoe crab eggs. But where did the birds from Tierra del Fuego go? They do rely on the eggs to gain weight fast and go on to breed in the Arctic. Did they give up and not reproduce, or were there widespread nest failures? We will have to investigate this in the future.
Another interesting question is why the red knot prefers the NJ side of the Delaware Bayshore. It’s been the case for over a decade, but we were shocked that when the main flock returned, they returned to NJ Bayshore habitats. We know several answers, none overwhelming, but added together. They provide some insights into the value of the NJ side of Delaware Bay for shorebirds.
The distribution of Red knots in Delaware Bay May as determined by ground, boat and aerial counts. Graphic from Feigin et al ( in prep)
The first glaring difference between the two sides of the bay is the absence of protection from human and dog disturbance on the Delaware side. NJ Fish and Wildlife erects rope barriers on all access points to the beaches important to shorebirds. Stewards trained by Conserve Wildlife Foundation often meet people visiting the beach to enjoy horseshoe crabs and shorebirds, explaining why the access restrictions help birds and people. Before restrictions existed, people roamed the beaches looking for good pictures or to see thousands of shorebirds feeding on crab eggs. The birds reacted by moving away, of course, and both birder watchers and birds suffered. With the restriction to viewing areas, the birds respond by feeding right up to the barriers, giving viewers fantastic views and birds access to high-quality foraging areas.
Each year NJ Fish and Wildlife protects all sites important to shorebirds during the stopover by restricting access to the beach. It is only for about one month and most residents are happy to keep people off the beaches. The restriction is lifted as soon as the birds depart.
The birds tagged with satellite tags help us understand more. Shorebirds not only need to feed but to roost safely. The proximity of superior foraging to a safe roost protects birds from the ground and avian predators. This safety allows them to digest guts full of horseshoe crab egg and casually store fat. A good roost also provides protection when birds get fat. Overweight birds are easy prey, so they need safe places to rest and digest.
The main roost for Delaware Bay knots lies just a few miles east in the NJ Atlantic Coast marsh. Deep water tidal creeks separate the Atlantic Marsh into marsh islands, unlike the bay marsh. It’s why we have ground-nesting gulls, terns, herons, and other species on the Atlantic coast marsh and only a few on Delaware Bay. No bird is safe from ground predators on the bay unless they hide like the ultra-secretive Black Rail. Nearly all the tagged birds spent time on the Atlantic coast to roost. An added benefit is they can also feed on clams and mussel spat, the normal diet for knots and other Delaware Bay shorebirds.
So proximity to the Atlantic Coast is one value absent from the other side of the bay, but there is more. Much of the NJ coastline of Delaware Bay is inaccessible. We divide the bay into three sections- Upper Bay ( Money Island to Mouth of the Maurice), Middle Bay ( Mouth of Maurice to Bidwells Creeks), and the Cape Shore ( Bidwells to Villas).
Nearly the entire Upper Bayshore can only be reached with a boat. The place is known for the towns of Fortescue and Gandy’s Beach, but they add up to only a fraction of the Upper Bayshore. It also includes Egg Island, the largest contiguous marsh in the mid-Atlantic, inaccessible except by boat, and the location of the largest roost of knots in the US ( over 16,000 birds).
The Middle Bay portion offers many inaccessible areas or areas poorly accessed by bad roads like Moores Beach or gated roads like Thomsons Beach. East Point, the site of the famous lighthouse, is where most people go to see the Bayshore, crabs, and birds, but this year knots and other shorebirds used small estuaries feeding into the mouth of the Maurice River. The site is owned privately by Nelson Klien, and he restricts access.
Adding to this section’s value to the birds, we found a significant daytime roost and perhaps a night roost on the bay east of Moores Beach, known as Cox Meadow. It mimics the island marsh of the Atlantic, but the 20 acres marsh is unnatural. It’s a fragment of the eroded marsh destroyed by the abandonment of Ezra Cox salt hay farm after the NJ Fish and Wildlife purchased it. After years of compaction and accelerated decomposition from tractor use and restricting the tide with dikes, the marsh dropped in elevation by several feet. Abandoning the dikes and exposing the area to tide created catastrophic erosion that destroyed a mile of beach and 400 acres of vegetated marsh. The old salt hay farm is a bay now with one remaining fragment of the old marsh surrounded by Bayshore on two sides and man-made ditches on the other two. It’s a ground predator-free roost, just like those on the Atlantic coast.
Red knots and other shorebirds roosted on the eroded marsh of Cox Meadow
On the final section of the bay, the Cape shore, most of the beach is accessible, but as said above, access is restricted, and stewards help people understand why.
The last significant difference between NJ and DE is beach restoration. The state of Delaware probably adds more sand to thier beaches than NJ by far. But they do it for recreational value, whereas in NJ, we do it for both resiliency and value to horseshoe crabs. We have been measuring horseshoe crab egg densities, so we know the difference between good and bad beaches for horseshoe crab spawning. Much of the sand added to DE Bay beaches is dredged and has a smaller grain size, likely .2 to .3 millimeters. It is better than mud for spawning horseshoe crabs, but it is harder to dig into and lay eggs and for the eggs to hatch and successfully emerge into the sea. In a project developed by the American Littoral Society and Wildlife Restoration Partnerships, we tested grain size impact on egg laying and resiliency, finding large grain sand much better for egg laying and survival.
Moreover, we try to reproduce the natural profile of the beach and protect the dune structure or rebuild it. Delaware creates large recreational beaches wide enough to accommodate beach recreation. It’s a very different method of beach restoration from NJ. Our studies, including this peer-reviewed paper, found that our restored beaches outperformed even natural beaches.
Sheryl Howe, a volunteer for Return the Favor project prepares to rescue crabs caught in the Phragmites on East Point
Add to this our various protection efforts like The Wetlands Institute’s Return a Favor Project which fields volunteers to right crabs overturned by bay waves or free them from impingement in rocks or derelict bulkheads. CWF Foundation trains volunteers to protect birds at access points. Our program trains local volunteers in shorebird banding and other skills. Altogether, we significantly influence the people living in the area who, more often than not, love horseshoe crabs and the shorebird migration.
It all adds up to this, the knots returned to the bay this year and are leaving in good condition.
Next Update
A horseshoe crab and eggs on the surface of East Point.
