Red Knots at the Delaware Bay, photo taken during Camp Avocet. (Photo by Dessi Sieburth)

Red Knots at the Delaware Bay, photo taken during Camp Avocet. (Photo by Dessi Sieburth)

Author: Dessi Sieburth

From July 28th to August 3rd, 2018, I attended Camp Avocet, a camp for young birders run by the American Birding Association (ABA). The Camp is stationed along the southern shore of the Delaware Bay. Late summer is a prime time to see migratory shorebirds, and during our six days at Camp Avocet, our main focus was to observe shorebirds in and around the Delaware Bay. The Delaware Bay, shared by Delaware and New Jersey, is considered one of the four most important shorebird migration stops in the entire world. Every spring (April and May) and fall (July to September), tens of thousands of shorebirds stop along the Delaware Bay to feast on the eggs of horseshoe crabs laid along its shore.

One of the species that depends on the Delaware Bay as a stopover location during spring and fall migration is the rufa subspecies of the Red Knot. This subspecies has an incredible migration, breeding in the arctic tundra of northern Canada and wintering almost entirely in Tierra del Fuego in southern Argentina. This journey of nearly 9,000 kilometers is almost entirely taken over the open ocean with just a few stopover sites. During the northbound migration, the Delaware Bay is the knot’s last stop before flying straight to the arctic for breeding.

Horseshoe Crabs, photo by Greg Breese/ USFWS

Horseshoe Crabs, photo by Greg Breese/ USFWS

Horseshoe crab eggs in hand, photo credit: Greg Breese/USFWS

Horseshoe crab eggs in hand, photo credit: Greg Breese/USFWS

In the late 1980’s the population of the rufa Red Knot was estimated at 90,000 birds, nearly all of which came to the Delaware Bay to feed on the horseshoe crab eggs every spring and fall. However, beginning in the mid-1990’s, birders started noticing a dramatic decline in the number of knots wintering in Tierra del Fuego. In 1997, only 41,855 birds remained. Just six years later, in 2003, surveys in the Tierra del Fuego showed the population to be at just 16,255 birds. Clearly, there were some major threats to these birds, but where were they coming from?

As it turned out, the threats came from the Delaware Bay itself. In the 1990s, fishermen began harvesting young horseshoe crabs, which made perfect bait for catching conch and fish. In the late 1990’s, up to two million crabs a year were being harvested. This decline in the horseshoe crab population meant fewer eggs for the knots to feed on. Each horseshoe crab lays 100,000 eggs, which are buried in the sand. The knots only gain access to the eggs that were inadvertently dug out by other crabs when laying their own eggs. Therefore, a large density of crabs is needed to provide enough food for Red Knots to sustain their migration. In 2004, scientists feared that the rufa Red Knot would become extinct within six years due to their drastic declines.

Bill Stewart, director of Camp Avocet had witnessed this decline firsthand when birding the Delaware Bay and did not want to see such a beautiful bird vanish. He was determined to reverse the declines of the Red Knot by protecting the Delaware Bay from horseshoe crab harvesting. In 2007, he took action and decided to raise money to buy shoreline so that it could be made off limits to crab harvesting. To raise money, he organized a birdathon in Delaware and New Jersey in which teams of birders would identify as many species as possible in a 24-hour day. The shoreline purchased was made part of Prime Hook National Wildlife Refuge. In the first year the birdathon raised $28,076 in donations, and in the 11 years since, has raised over $400,000 and has protected 1,279 acres of the Delaware Bayshore habitat. Since the reproductive cycle of the horseshoe crab is six years long, it took time to see an increase in the Red Knot population. Surveys in 2011 in Tierra del Fuego counted 9,850 birds, and in 2017, surveys recorded 13,127 birds. However, in 2018, the population decreased by 25 percent to 9,830 birds, probably as a result of the exceptionally cold waters in the Delaware Bay that led to a poor year for the crabs.

Bill Stewart at Stone Harbor Point, New Jersey. Photo by Holly Merker

Bill Stewart at Stone Harbor Point, New Jersey. Photo by Holly Merker

Thanks to efforts like Bill Stewart’s, we were able to see a couple hundred Red Knots along a beach in New Jersey across from the Delaware Bay. Seeing the rufa Red Knots, which are still listed as threatened, was one of the many highlights at Camp Avocet. On our first day at camp, one of the camp counselors spotted a Great Cormorant sitting on a pole in the Delaware Bay. This Great Cormorant was just the second summer record for Delaware! Shorebirds at Camp Avocet did not disappoint, and by the end of camp, I had seen 23 species of shorebirds! Other highlights for me included nesting American Oystercatchers, Piping Plovers, and of course, American Avocets. The plovers were especially a treat to see since they are endangered due to increased development and recreational use of beaches.

6 knot in flight

Red Knot in flight in New Jersey, photo by Kevin Karlson

We don’t know yet if the Red Knot numbers will increase in the future, but the Delaware Bay is an example of how conservation efforts can protect shoreline, providing hope that Red Knot can be saved. To learn how to help birds please visit my website https://protectingourbirds.my-free.website/.

Special thanks to the American Birding Association for providing me with a scholarship and Pasadena Audubon Society for providing me with a grant to attend Camp Avocet.

Red Knot in breeding plumage. (Illustration by Dessi Sieburth)

Red Knot in breeding plumage. (Illustration by Dessi Sieburth)

Literature cited:
Rosenthal, E, (2009) Help the Delmarva Ornithological Society Help the Red Knot
https://www.nj.gov/dep/fgw/ensp/pdf/end-thrtened/redknot.pdf
https://delawarebirdathon.com/bird-a-thon-conservation-successes/
https://www.nj.gov/dep/dsr/trends/pdfs/wildlife-redknot.pdf
https://www.birdlife.org/worldwide/news/red-knots-plummet-25-one-year-tierra-del-fuego

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