Cleaner harbor lures water birds to New York

Despite noise, odors and traffic, herons, egrets and other species thrive

January 10, 1999|By New York Times News Service

NEW YORK -- Each year, 1,700 tankers bring 18 billion gallons of oil into New York Harbor. And each day huge barges carry 14,000 tons of garbage to the Fresh Kills landfill on Staten Island.

The harbor, also heavily trafficked by container ships, gravel boats, tugs and pleasure craft, hardly seems a good place for fish-eating birds to settle and raise their families. Surely they would never choose to live among the flotsam and jetsam and just plain trash washing up on the shores, or among wrecked ships and docks and long-abandoned buildings on islands that look nothing like a wildlife refuge. Surely elegant snowy egrets or black-crowned night herons would never call a place like that home.

Yes, they would and they do.

In the last two decades, undeterred by PCBs, noise, odors and other types of pollutants, exploding populations of herons and egrets, glossy ibises and double-crested cormorants have joined the ubiquitous gulls that call the harbor home. Thousands of long-legged waders have no compunctions about nesting in unkempt spots or dining on fish and shellfish from polluted water. Although, to humans, several of the harbor islands and their environs may look like slums, to the birds they resemble an Everglades paradise, replete with food and nesting sites and free of threats from people, raccoons and most other predators.

Returning from the edge

Several of the species now thriving here had been threatened with extinction; others had never been known to nest near New York City. Their expanding presence in the harbor is testament to the incredible resilience of nature, once it is given half a chance.

The birds live, breed and feed on islands never visited and rarely noticed by most New Yorkers despite their proximity to the five boroughs: North and South Brother Islands between Queens and the Bronx; U Thant Island in the East River, a hefty stone's throw from the United Nations; Shooter's Island in the Kill (or stream) Van Kull; Prall's Island and the Isle of Meadows in the Arthur Kill between Staten Island and New Jersey; and Swinburne and Hoffman Islands in lower New York Bay between Brooklyn and Staten Island.

These harbor islands, along with the islands of Jamaica Bay and a few islands east of the Bronx in Long Island Sound, comprise fewer than 1,000 acres, said Dr. Paul Kerlinger, an environmental consultant. Yet Kerlinger reported in the current issue of Living Bird Quarterly, the annual surveys he conducts with volunteers from the New York City Audubon Society, that the harbor islands alone are breeding grounds for nearly 1,000 pairs of black-crowned night herons and several hundred pairs each of snowy egrets, great egrets, cattle egrets and glossy ibises.

Cormorants thriving

This is not to mention the rapidly expanding populations of double-crested cormorants, sleek black fish eaters that had not been known to nest in New York Harbor until eight years ago. There are now about 960 breeding pairs of cormorants in the harbor, where the federally protected birds have so far escaped persecution by fishermen who elsewhere view them as competition.

"This certainly says something about the quality of the water," said Peter Mott, president of the New York City Audubon Society, as he toured the islands by boat recently. Mott said that in 1960 no egrets or ibises were nesting in the harbor and a mere sighting of an ibis in 1950 "was so unusual that I played hooky from school just to see one."

He credits the Clean Water Act of 1972 for the fact that the harbor is now hospitable to myriad aquatic species -- from snails and tiny shrimp to crabs and bait fish -- and the long-legged wading birds that depend on such fare.

"In 1970, if you put mummichog into the Arthur Kill in summer, it quickly died for lack of oxygen," he recalled. Mummichog, a salt marsh fish used for bait, is a favored food of black-crowned night herons, among other waders. The Clean Water Act mandated a reduction in the amount of fecal and other organic matter that could be contained in the effluent of sewage treatment plants. This meant that there was less oxidizable material in the processed sewage, which in turn meant that oxygen levels in harbor waters into which the treated sewage was dumped could rise to a point that could sustain aquatic life.

"When the level of dissolved oxygen falls below 3 parts per million, the water can't support most fish life or invertebrate life," Mott said. "Now in the Arthur Kill, 64 percent of the freshwater comes out of sewage plants."

But organic matter from sewage is not the only contributor to an oxygen shortage in waters surrounding a big metropolis like New York. Mott said that runoff from the rain and snow that reaches the harbor has very low oxygen levels.

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