previous update
Dear Team,
With only small groups of knots and turnstones still on the NJ side, we closed the main house, and we intend to trap only if new birds arrive. As of today ( June 1 2021) we are down to about 300 knots at Norbury’s landing, 350 knots at Thompson’s beach, and a scattered few more in various places. Ruddy Turnstone’s numbers are similar. This is down from the May 26, 2021 count of 6880 red knots 10,785 turnstones, 16965 sanderlings 48225 semipalmated sandpipers. We will conduct a boat count tomorrow, June 2, and continue scanning these flocks this week to ensure we see newly arriving birds.
Unless more birds come in, The Delaware bay stopover population has declined from a recent high of over 30,000 birds to just under 7000. If this year compares to the losses documented by Allan Baker in his 2004 paper, the population may have suffered 37% mortality.
The historgram shows the number of red knots in dark blue and ruddy turnstones in gray, from aerial counts of Delaware Bay Stopover from 1982 to 2021. The count in 2021 was the lowest for both species in the entire time series. .
Knowing the cause is vital. At this population level, the stopover could fail altogether. Stopovers have collapsed in many places on the knot’s 10,000 mile-long flight path. The same is true for stopovers around the world. And it’s hard not to forget we are also in the middle of a global extinction crisis like few others. Rufa knots, especially long-distance red knots, could be lost. We must do our best to understand a cause or group of causes on which we can act.
We need to avoid settling on unfocused causes like climate change because shorebird and horseshoe crab advocates can’t change that. Industry often points to global problems to avoid the financial or political impacts of their natural resource destruction. The industries killing crabs or destroying habitats have always been quick to point out broad excuses that resolve them of responsibility.
We should also avoid the pitfalls set by industry-funded or politically influenced studies that absolve the industry of any responsibility to conserve. Read Chiara Eisner’s description of how Charles River Lab, the company bleeding most horseshoe crabs, pays for studies that mislead and fudge the truth.
Fudging the truth for the sake of industry has already damaged the Delaware Bay stopover. During the period of most significant threat, when numbers fell from a high of over 90,000 red knots in the 1980s, declining to around 17,000 in the 2000s, one conservation group published a report suggesting those declines were a consequence of knots arriving later year after year. They were not, but the industry loved the idea and used it to delay meaningful reductions in the horseshoe crab kill. The group has yet to reject the publication.
The problem was then as it is now. There are too few horseshoe crab eggs to support the stopover population. This was true in the 1990s because large numbers of 6 different shorebird species came to the bay expecting the largess of a healthy crab population and instead found few eggs and intense competition. Egg densities went from 50,000 egg/sq meter to 5000 eggs/sq meter. Many birds died until their number equaled the bay’s ability to support them.
But the agencies still allow the killing of nearly 3/4 million horseshoe crabs from Delaware each year. The density of eggs is still less than 10,000 /sq meter on average, and the spawn is squeezed into brief periods around the new and full moons. Last year the bay’s water warmed slowly, and the peak of spawning fell outside the period shorebirds used the bay. Most left the bay without any benefit of eggs. If the crab population were equal to what the birds found in the 1980s, the abundance would have saved the birds.
This time, the fishing and blood industries will almost certainly point to the 2019 stock assessment and say birds are stable. They will say there are enough eggs and they can’t do anything about cold springs.
But they wont say this. Nearly one and a half million new adult female horseshoe crabs enter the bay’s population every year, yet the numbers of females, according to the Virginia Tech Trawl, have not gone up in the 20-year life of the survey. The agencies report a kill of around 100,000 adult females a year but don’t ask the obvious question – who or what is killing the remaining 1.4 million adult females each year?
This excerpt from Rujia Bi, David Hata and Eric Hallerman’s report on the Delaware Bay trawl of Horseshoe crabs emphasizing the addition of about 1.5 million adult female crabs to the Delaware Bay population almost every year. Yet the ASMFC has not explained where or how these crabs die apart from the self-reported and unverified kill of the multi-national bleeding companies.
It should be clear from recent developments in SC, that regulation is loose and compliance poorly monitored. Perhaps the only reasonable way is to restore the population to carrying capacity is to close down the female kill altogether until the numbers of adult females and eggs start rising.
We should focus on this simple request. We should be managing the bay’s population of horseshoe crabs for the worst conditions the bay can unfold. We can’t stop bad winds or cold water, but we can expand the population of horseshoe crabs, so birds arriving in most of these conditions find an abundance of horseshoe crabs eggs. It’s a simple prescription – stop the killing of female horseshoe crabs.
Larry Niles
next update
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.
