The plight of the Atlantic Red Knot has been gaining an increasing amount of attention, here in the Northeast United States. This beautiful bird relies on the presence of horseshoe crab eggs, in the Deleware Bay, for food and energy during its bi-hemishperic migration.
The following article appeared in the Asbury Park Press, New Jersey, June 1, 2008
It was written by Kirk Moore
MAURICE RIVER — Nasty spring weather and the Mother's Day northeast gale disrupted Delaware Bay's horseshoe crab spawning season and the diet of migrating red knot shorebirds that eat crab eggs.
Now, scientists say, the birds are thin as they have ever seen.
After early 2008 winter counts in South America showed red knots at an all-time low, biologists say there's not much margin left to keep the western Atlantic red knot subspecies from slipping closer to extinction, if they don't get enough food this week before the final leg of their annual flight north to breeding grounds in Canada's Arctic.
"For the first time in 12 years, when I sent an update back to Australia, I've used the words "The birds are starving,' " said Clive Minton, who works on an international group that has helped New Jersey state biologists monitor red knots since the mid-1990s.
"But in the last five days, the weather has calmed down and warmed up, so they're putting on weight," Minton said as the team mounted up Friday to catch and release red knots and check their weight gain. "It depends on the next three or four days."
Conservation groups such as the New Jersey Audubon Society and advocates for commercial fishermen battled through last winter, until the state Legislature and Gov. Corzine imposed a total ban on taking horseshoe crabs for use as bait in fish traps. Watermen's crab harvests had already been severely restricted for years, after New Jersey and Delaware state officials cracked down in the 1990s to stop bait dealers from clearing love-struck crabs off bay beaches in May.
Meanwhile, work by state Department of Environmental Protection biologists and their colleagues from Canada, Argentina, the United Kingdom and Australia showed the western Atlantic red knot numbers bottoming out around 17,000 birds in the last few years. But then last winter saw a big die-off in South America, and researchers estimated the red knot population may have slipped below 15,000 birds.
On Friday, the team hiked out to Moore's Beach, a former bayside settlement where only stubby wood pilings and scattered bricks remain of the old summer colony.
Along a tidal creek, the researchers placed their most valuable tool: a pair of black powder-powered mortars that fling a net over shorebirds as they peck for horseshoe crab eggs in the shallows.
After netting about 70 red knots and assorted other birds at Moore's Beach on Friday, DEP biologist Amanda Dey set volunteers to work measuring, weighing and banding the birds before release. Her husband, Larry Niles, chief scientist with the Conserve Wildlife Foundation of New Jersey, hovered around the groups and listened as workers measured and weighed birds.
"I'd rather see them over 180 grams by now," Niles fretted, as birds weighed in between 150 and 179 grams. Weight gain is a key indicator of the red knots' future chance of success with migrating and raising young in Canada's far north. If they don't eat enough here to build up fat reserves, the red knots will fall short, like jet fighters flaming out.
"If they get to 180 (grams body weight) the energy in that fat is enough to get them to the Arctic," Niles said. "Back in the old days, we regularly had birds going over 200 grams. Now, it's a rare event."
Once he made the rounds of wildlife pros and volunteers measuring the birds, Niles felt better. "There's a mix," he reported. "Some birds are making above 180 grams."
"We've got a fatty!" announced Anneke Walsh, 11, whose family came from Bryn Mawr, Pa., to help with the sampling. A bird had just tipped the electronic scale at nearly 200 grams.
The team lives in a rented house at Reed's Beach in Middle Township and gets a lot of help from a local environmental group, Citizens United to Protect the Maurice River.
"We have about 40 volunteers working on this. We call it "Host the Scientists.' Clive calls it "Meals on Wheels,' " said Jane Galetto of Citizens United. The group organized extracurricular birding trips and hospitality for the researchers, like a nighttime stance with the spooky owls of Cumberland County's woods and a pig roast and game dinner.
Niles and Minton said the mid-May gale was especially destructive to horseshoe crab beaches on the Delaware state side of the bay. After this tough spring, it looks like creeks on the Jersey Shore are a haven for crabs and birds, they said. The Mother's Day storm churned up some buried crab eggs for birds that arrived early. But crab spawning activity went flat after that, Minton says.
"Most big departures (of red knots to Canada) historically started around May 25," he said. "The question now is will they get to a satisfactory weight, and will they get to it in time?"
What the storm eroded away on the Delaware side may have been compensated in New Jersey, Niles said. Shoals now are bigger at Moore's Beach and created a haven, he said. The birds had been limping along for a week, Niles said. "Then the creek began filling up with crabs.
"We've had a third or more of the red knot population in here for most of the season," Niles remarked as he scanned the creek inlet near Moore's Beach.
On the usual bay beach spawning grounds, crabs have been scarce, Niles and Minton said. But the upcoming lunar high tides could bring in a big surge of the animals and their eggs, to give the birds one last energy boost before takeoff.