Human Intervention Spurs Recovery

This is the first in a three-part series on endangered species.
Efforts to restore the natural habitats of endangered and threatened non-game species are showing signs of progress, according to experts who have been studying the patterns of ospreys, bald eagles, peregrine falcons, horseshoe crabs and other species that stop along the way or make their homes along the Delaware Bay in Cape May County.
However, the progress that has been made is not enough to restore these species to what conservationists would like to see.
In addition, the life or death of these species is an indicator of the health of the surrounding environment and could impact a growing economy across the county that saw tourists spending $6.6 billion last year.
A Critical Stopover
Flowing from the Catskill Mountains to the Atlantic Ocean, the Delaware River is the heart of the four-state region comprising New York, Pennsylvania, New Jersey, and Delaware.
Cities, towns, farms, forests, mountains, marshes, beaches, and more are all connected by the longest undammed river east of the Mississippi River and its 2,000 tributaries.
The Delaware River watershed is defined by its diversity. It encompasses the most densely populated urban areas in the nation, yet remains 50% forested, according to the U.S. Fish and Wildlife Service.
The Delaware Bay’s shores are a critical stopover area for six species of migrating birds, including Red Knots, sanderlings, ruddy turnstones, and Semipalmated sandpipers.
The late May arrival of these birds coincides with the spawning of horseshoe crabs, producing one of the most dramatic natural phenomena anywhere in the world, according to the state Department of Environmental Protection Division of Fish and Wildlife.
Feeding on crab eggs, the birds refuel and continue their journey to Arctic breeding grounds. There has been a dramatic decline in horseshoe crab numbers since 1991 and a corresponding decline in shorebird numbers.
Ospreys, Bald Eagles Decimated
Ospreys and bald eagles were “decimated” post-World War II, according to Eric Stiles, president and CEO of the New Jersey Audubon Society, because of pesticides used in households and on farms, DDT (Dichlorodiphenyltrichloroethane) in particular.
The chemical is passed along in the food chain and affected the thickness of egg shells.
“The birds would sit on their eggs and crack the shells because they were so thin,” Stiles noted.
By the time the pesticide was banned in New Jersey in 1968 and in 1972 for agricultural use in the nation, Stiles said suburban crawl also had destroyed much of the Ospreys’ habitats. “Ospreys typically breed in their third year,” he added, noting their preference for tops of dead trees.
Consequently, the Osprey was one of the first species to be included on the New Jersey Endangered Species List when the New Jersey Endangered Species Conservation Act passed in 1974.
With this legislation came the establishment of the New Jersey Endangered and Nongame Species Program (ENSP), a team of biologists dedicated to the conservation of New Jersey’s imperiled wildlife.
In 1979, the ENSP began an osprey reintroduction program in which biologists transplanted eggs from healthy nests in the Chesapeake Bay area into active, but unsuccessful, New Jersey nests.
In addition, the recovery plan for the Ospreys called for homes to be built for the birds, including platforms in the salt marshes of Cape May County. Volunteers built the platforms and others contributed funds, turning around the species from about 60 pairs in the early 1970s to some 500 nesting pairs today.
Stiles credited this effort with the “amazing” turnaround of a bird that found itself moving from “endangered” to “threatened” in New Jersey in 1985, becoming the first species to be removed from the state’s “endangered” list.
ENSP continues to monitor their health as an indicator of many coastal species, as they are sensitive to contaminants and the viability of the aquatic food chain.
“It’s like a field of dreams,” said Stiles about the increase in numbers, “build it (platforms for nests) and they will come.”
The bald eagle has a similar story as it was removed from the federal “endangered” list in 2007, but remains on the state’s “endangered” list during breeding season and is “threatened” during its non-breeding season.
From 1972-84, Stiles said there was one pair of bald eagles in New Jersey, making their home in Bear Swamp in Cumberland County. Today there are 200 statewide.
“The bald eagle has up to three young a year,” he said, “and typically that third one is the runt who doesn’t survive. So we took that third eagle to places where DDT wasn’t used and raised them in artificial nests. We raised them in Canada, the Hudson River Valley, Delaware and Chesapeake Bay areas because they return to where their nest is. It jumpstarted the population.”
Fastest Bird Affected by DDT
Another bird affected by DDT was peregrine falcons, which, as the fastest bird in the skies, have fascinated people for centuries.
Peregrine numbers fell due to the effects of DDT, which caused their eggs to fail and they became extinct east of the Mississippi by 1964.
They were one of the first birds to be the focus of conservation, however, through an intensive reintroduction program, returned to the skies in New Jersey and other eastern states in the 1980s.
The peregrine falcon was classified as a federally endangered species in 1970 and as a New Jersey endangered species in 1974. The following year (1975), a peregrine falcon recovery plan was initiated in the east. The goal of the plan was to restore the breeding population to at least half of pre-DDT levels.
This resulted in an eastern goal of 175-200 pairs, a mid-Atlantic regional goal of 20-25 pairs, and a New Jersey goal of eight to 10 pairs.
During the late 1970s, biologists released young peregrines into the wild throughout their former range. This process, known as hacking, was hoped to re-establish nesting populations, as peregrines often return to their natal sites to breed.
Peregrines released at cliff sites experienced high mortality due to great horned owl predation (the preying of one animal on others), causing biologists to erect manmade nesting structures in coastal marshes where owl numbers were lower and prey was abundant.
In 1980, peregrine falcons nested at Edwin B. Forsythe National Wildlife Refuge in Atlantic County, the first nesting attempt in the state and the eastern U.S. in nearly a quarter century.
The population in New Jersey has been about 20-24 pairs annually since 2000. In New Jersey, peregrines nest along the Atlantic coast from Ocean to Cape May counties, and on Delaware River bridges from Burlington to Cumberland counties.
Prior to 2003, all nests were on manmade structures that included nesting towers, water towers, large bridges, and high-rise buildings. In 2003, peregrine falcons returned to their historic cliff-nesting habitat on the Hudson River Palisades, a huge milestone in the peregrine’s recovery in the state and the region.
Because national recovery goals were met, the peregrine falcon was removed from the federal endangered species list in 1999.
Despite the fact that the peregrines have met state numerical recovery goals, their continued listing as endangered in New Jersey is warranted. They remain threatened by environmental contaminants and human disturbance and rely on active management of their nesting sites.
Red Knot Recovery: An International Effort
The recovery of the Red Knot species, however, wasn’t that simple because that bird crosses national and cultural boundaries on its 6.5-month roundtrip journey from Tierra del Fuego, Chile, to breeding grounds in the Arctic, a 20,000-mile roundtrip. It also depends on another species, horseshoe crabs, for food.
In 1999, the Red Knot was listed as a threatened species in New Jersey under the New Jersey Threatened Species Act. As a result of the Red Knot Status Assessment in fall 2006, the U.S. Fish and Wildlife Service announced the Red Knot as a candidate for federal listing and the Committee on the Status of Endangered Wildlife in Canada recommended listing the Red Knot as endangered in April 2007.
The state Department of Environmental Protection (DEP) is taking a multifaceted approach to protecting this species and its habitat through shore protection initiatives and restoration of beaches to increase the available spawning habitat.
The Red Knot’s decline is a warning that something larger is happening to the bay’s ecosystem, however, and steps must be taken to protect this ecosystem and its wildlife or it may disappear forever, according to a U.S. Fish and Wildlife Service brochure.  
The bird spends seven to 10 days on the Delaware Bay beaches eating horseshoe crab eggs to double their body weight. According to the DEP, the bird must gain a minimum of six grams of weight per day while in the Delaware Bay area to complete its journey to the Arctic and successfully breed.
Red Knots gained about eight grams per day in 1997; now they gain about two grams per day.
This weight gain is critical for survival because the Delaware Bay is the last stop before the Red Knots reach still-frozen Arctic breeding grounds, where it takes one to three weeks for insect food to become available. The fat reserves put on in the Delaware Bay area allow Red Knots to survive and continue courtship, mating, and egg-laying until food becomes available. Without a sufficient fat reserve, the consequence is loss of reproduction, or death.
“Teams of scientists along their path had to come together, embrace their diversity to develop a plan for recovery,” Stiles said. “We agreed how to measure and monitor and act cohesively to determine what actions would have the greatest impact on the Red Knots.”
According to the U.S. Fish and Wildlife Service, the Red Knot population decline that occurred in the 2000s was caused “primarily by reduced food availability from increased harvests of horseshoe crabs, exacerbated by small changes in the timing of when the Knots arrived at the Delaware Bay.”
Less than two decades ago, more than 100,000 Red Knots filled the skies of the bay region during their epic migration.
In January 2019, the Western Hemisphere Shorebird Reserve Network (WHSRN) successfully conducted aerial surveys of the Red Knots wintering in Tierra del Fuego, South America. This year’s surveys revealed a total of 13,190 birds.
“This is a welcome return to the more typical numbers from recent years, after the lowest-ever count of 9,840 birds in January 2018,” according to the WHSRN. “As recently as 2000, the population numbered over 50,000 birds, but during the following decade it crashed to around 10,000 birds by January 2011. Since then, the annual survey total has varied between about 10,000 and 14,000.”
Part two of this three-part series will appear in next week’s Herald, June 19.
To contact Karen Knight, email kknight@cmcherald.com.