Previous Update
Much has happened since my last update.
On May 22, we completed the first boat and ground count of NJ beaches, and the count topped last year’s by at least 8000 knots, coming in at 22,107 red knots. In 2019 we counted over 30,000 red knots, but after the bay’s crab spawn failed to materialize in May 2020, the number crashed to 19,000, then to a disastrous 6000 in 2021. Last year the knot numbers bumped to 12,000, giving us hope for the stopover. The increase to 22,000 is good news that tells us a lot.
The first part of this good news is that the birds have returned to the bay. Two years ago a report by Mark Farrighty of Mass Audubon documented that one knot first seen in Delaware Bay and then resighted the next day in Mass alarmed us. It meant birds bypassing the bay because the stopover was no longer a reliable source of eggs. Moreover, Felicia Sanders in South Carolina reported a growing number of knots flying directly to the Arctic from SC. The value of South Carolina to shorebirds increased this year when a Judge stopped an international biomedical company, Charles River, from removing horseshoe crabs while spawning from the many islands in the South Carolina mostly natural coastline. Ending the killing meant more eggs and potentially more birds staying in SC. We worried that the unrelenting killing of crabs for bait and blood would make the Delaware stopover so unpredictable that it was longer relevant to the birds. The returning knots told us a different story.
The count of red knots ruddy turnstones and sanderlings done by the NJ Shorebird team on the NJ shoreline of Delaware Bay on May 22,2023
Red knots increased in 2022 and 2023 following drastic declines in 2020 and 2021 resulting from the cold water shut down of the horseshoe crab spawn in 2020. The same thing occurred in 2003 and it took years for numbers to recover to a much lower number than before the overharvest of horseshoe crabs
This is the second bit of good news, nearly all the knots found in the bay returned to the NJ coastline, where beaches are restored by the American Littoral Society and protected by NJ Fish and Wildlife and Conserve Wildlife Foundation. Wetlands Institutes field volunteers with the Return the Favor program that rescues many horseshoe crabs yearly from impingement and overturning. We have fashioned a world-class protection system in NJ over the last 20 years of management. Following adaptive management, we have restored eroded beaches, adding sand and offshore reefs to protect the beaches and then studying the impact. When we do it again on another beach, we use the lessons learned to improve the restoration. But beaches that nurture horseshoe crab spawning and foraging shorebirds would still be empty if people chased birds from the beach to the beach, trying to appreciate them. Instead, NJ Fish and Wildlife restrict access to the most important beaches, and CWF field stewards to explain the need for the restriction. This allows birds to forage on the beach, and the bonus is they feed right up to the rope barriers allowing viewers to see birds up close.
Images on the right show the restoration of two beaches from their eroded conditions shown on the left. .
Barbara Bennett, a volunteer with Conserve Wildlife Foundation Shorebird Stewardship program, prepares to protect Cooks Beach NJ. NJ Fish and Wildlife and CWF field stewards each year to educate people on why beach closures help shorebirds.
Finally, the count puts to rest the suggestion made in a recent article by the USFWS that questioned the validity of the declines we reported in 2020 and 2021, leading to the state Fish and Wildlife Agency taking back control of the aerial count of shorebirds that we have been doing for the last 15 years. Admittedly aerial counts entirely depend on the counter and are subject to wide variation. We bound this with ground counters in all important accessible beaches and a boat count covering all inaccessible beaches. We then compare the counts to estimate the most accurate number of birds. The implication of agency actions is the decline in knot numbers in 2020 and 2021 was not real. Ironically, the agency aerial count estimated only 9,149 in NJ where we counted 22,107.
Mandy Dey and I conducted the boat count on the 2021 all Delaware Bay count. In view the plane with Stephanie Fiegin, Alinde Fojic and Theo Diehl conducting the aerial count. We did two all bay counts this year by boat, plane and on the ground.
But the declines were real and told a story agencies wished not to hear. The birds stopped coming to the bay because the egg densities fell to almost nothing in the second and third week of May 2019. Water temperature was the proximate cause. After the water warmed, the spawn resumed in the fourth week, and by June, we counted a fair number of eggs. The year after, the birds knew no eggs were in the bay and bypassed us. Some came back in the second year after the cold water year. And now, in the third year, even more returned. The agencies will blame the cold water, but that is unworkable. How can we change the water temperature?
A graph taken from Smith el 2022, a paper on the history of horseshoe crab egg densities on Delaware Bay since the first egg surveys
Moreover, these cool Mays may be the new normal. With Climate change slowing the Gulf Stream, some predict cooler springs in the mid-Atlantic. In 2003 cool water also slowed the spawn just at the time when the agencies were finishing up the overharvest of the late 90s when over 2.5 million crab/year were taken for bait. The bay’s population of shorebirds plummeted, and it took years for birds to return to higher numbers, but never again reaching the numbers seen before the overharvest. The only way to respond to variations in water temperature is to stop the killing of horseshoe crabs.
The kill of horseshoe crabs reported by the ASMFC
Why is killing fewer crabs the answer? Because in 1987, cold water cut egg production from over 50,000 eggs/sq meter to 50,000 eggs/sq meter, five times more eggs than we have now in a good year. If more crabs were spawning, the egg’s densities would still be enough to fulfill the bird’s needs regardless of normal fluctuations in water temperature.
Why keep killing crabs? We waste them as bait for declining or overfished populations of eels and conch. At least the eel should be protected, and other baits can work anyway. The blood companies refused to back synthetic lysate and instead gobble up profits using crab blood for manufacturing a product that can be made in a lab.
We conduct a second baywide count tomorrow, the 26th, but birds have been leaving the bay, and the count may be lower.
We trapped twice over the last four days capturing red knots, turnstones, and sanderlings. The bird’s weights are building nicely. A catch yesterday, May 23, showed many sanderlings weighing in over 80 grams, the threshold needed to reach the Arctic and breed successfully. About 3/4 of the Turnstone also weighed in above thier threshold of 155 grams. We attempt a knot catch today to find out how knots are faring.
The reason for the excellent weights is good egg densities. Water temperatures this year were nearly perfect. The bay warmed early, spurring horseshoe crab spawning early in May. Early spawning helped build eggs in the sand before birds arrived. The spawn continued and peaked with the new moon of May 19. Even now, on the 25th, the spawn continues.
Next Update
The NJ Shorebird team after the ruddy turnstone and sanderling catch. From the right Gwen Binsfeld, Barrie Watts, Jack Mace, Jeannine Parvin, Lisa Kercher, Stephanie Feigin, Susan MOody, Ren Monte, Charles Duncan, Joanna Burger, Mike Gochfield, Anna Ausems, Larry Niles and Mandy Dey ( where is Humphrey Sitters?)
