The red knot. Photo by Don Chernoff.
by David Wheeler
Like many of us, the red knot — a plump shorebird with mottled brown wings and a bright salmon-colored head and belly — plans its early summers around a stopover at the Jersey coast. Red knots’ two- to three-week stay in New Jersey’s Delaware Bayshore is part of one of the longest migrations in the animal world. The 10,000-mile one-way journey takes these wondrous birds from sand flats at the furthest tip of South America, Tierra del Fuego, up to the icy arctic tundra of far northern Quebec.
One of the key stopovers is the Cape May bayshore. The red knots’ May and June stay on the Bayshore is far from a leisurely vacation, however. The shorebirds must eat enough horseshoe crab eggs to provide energy for their return to the Arctic breeding grounds in northern Quebec.
“The red knots are banking on a huge food resource at Delaware Bay, with the eggs so rich in protein that they can move on after only a week’s stopover in some cases,” says Amanda Dey, a New Jersey Fish & Wildlife researcher who has studied the red knots both in South America and the Canadian arctic as well as in Cape May.
For decades, that bayshore food source was a fait accompli. No longer, however, can red knots count on vast amounts of horseshoe crab eggs to tide them over.
Horseshoe crabs provide vital food for red knots.
“When we went up to the arctic, it’s a pretty harsh place, and those fat reserves they take from the bay are really critical for them to survive in that environment,” says Dey. “It’s not a far stretch that birds leaving the bay unprepared may not be reproducing and may not be surviving.”
On the Cape May bayshore, the last high tide in May once brought the prehistoric crabs ashore to lay their eggs in numbers that rivaled any mass wildlife event across the world. Local fishermen had long harvested some of the crab eggs as bait for eels, but by the early 1990s, a burgeoning market for eel and conch fishing spelled the end of such a sustainable harvest.
“Trucks would come up onto the beach to harvest the crabs, taking thousands of the biggest, oldest, most reproductively viable crabs in a few hours,” says Dey. “Horseshoe crabs take ten years to mature, so that’s the worst way to harvest them — and that’s what they were doing.”
According to recent studies, the red knot population is down to a quarter of its former size, with New Jersey Audubon estimating a total population of approximately 20,000 red knots. Dey and other Fish and Wildlife researchers will spend a few weeks at the Delaware Bayshore in late May surveying red knots and horseshoe crabs, as well as two other at-risk shorebirds — ruddy turnstones and sanderlings.
With red knot numbers declining severely with each year, officials in the states along the Delaware and Chesapeake Bays — Delaware, Maryland and Virginia, as well as New Jersey — face the question of whether to limit the harvests, and in turn fight the political opposition engendered by such a ban.
With the strong support of conservation groups, New Jersey took the proactive lead in this regional ecological battle. The state passed a moratorium on harvesting horseshoe crabs in March 2008, with the moratorium to last until sustainable numbers return. Violators face a fine of $10,000.
“The decline in New Jersey’s horseshoe crab population has left the red knot perched on the edge of extinction,” the bill’s sponsor, Assemblyman John McKeon, said at the time. “We simply cannot allow an entire species to be wiped out when the ability to halt the red knot’s decline is within our reach.”
By shutting down harvesting for several years, New Jersey horseshoe crabs can grow to maturity and expand their numbers back towards their previous levels. Unfortunately, the other states haven’t established the same protections. Until Delaware, Maryland and Virginia follow suit, according to Dey, it will be difficult for the horseshoe crabs and red knots to recover.
“Time really is the issue here,” she says. “Barring an indefinite full moratorium, I think we’ll see the horseshoe crab managed at a very low level. I’m sure the crab population can persist at a low level, but not in enough numbers to really help the birds.”
In the meantime, the red knots continue their timeless annual flight across the hemisphere. Ten thousand miles to go — next stop, New Jersey.
Green Jersey contributor David Wheeler is the founder of WildNewJersey.tv and director of operations for the Edison Wetlands Association.