Osprey eggs tested for signs of toxins

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Osprey eggs tested for signs of toxins

Results will help show how severely wildlife is affected by river pollution

By MOLLY MURRAY

Sussex Bureau reporter

05/22/2002

Gathering osprey eggs is no easy task.

Atop abandoned utility poles or on remote marine channel markers, the twiggy

nests are mostly inaccessible. Plus, the birds are big, and they don't like

strangers.

Despite these obstacles, a team of researchers is taking about a dozen

osprey eggs from nests along some of the most industrialized stretches of

the Delaware River to determine what effect pollution has on this link in

the food chain.

B. , a manager with Delaware's Coastal Management Program, said

the bottom sediments of Delaware Bay have been monitored for toxins, and the

fish have been tested too. Traces of PCBs, mercury and other toxins were

found in fish, but little is known about how the toxins affect birds and

other wildlife.

said scientists think ospreys, which can live 25 years or more, could

be useful sentinels to monitor environmental contamination.

Birds of prey such as ospreys served as sentinels more than 30 years ago,

when scientists noticed their eggshells were thinning from exposure to the

pesticide DDT. After the pesticide was banned in 1972, ospreys made a

comeback in Delaware. They started in the sheltered waters of Rehoboth,

Little Assawoman and Indian River bays in Sussex County. Dozens of ospreys

now nest along Delaware's Inland Bays.

As they spread past the available habitat in the Inland Bays, ospreys

expanded their range north into urban areas along the Delaware River and its

tributaries.

The river water beneath their nests is now clean enough for fish to thrive

there, but the bottom sediments are still tainted with toxic chemicals.

When fish eat aquatic worms and other creatures that live on the bottom, the

chemicals accumulate in the fishes' fatty tissue.

When birds feed on the fish, the chemicals are passed up through the food

chain.

State and federal officials want a baseline of data so they can spot any

contamination of the osprey eggs and see whether it gets better or worse

over time.

The study of the birds depends on a climber, like Craig Koppie, to get a

small number of osprey eggs.

On a recent day, Koppie, an endangered-species biologist with the U.S. Fish

& Wildlife Service Chesapeake Bay Field Office, put on special climbing

spurs and used ropes to ascend a wooden pole near Churchmans Marsh, near

Stanton. From the top, he could see the interstate highway, a junkyard and

the E.I. DuPont Newport Landfill and Koppers Co. Facilities site, both of

which are on the federal Superfund list.

Overhead, the agitated female bird screamed.

Koppie looked at his watch and started timing. He didn't want the mother

bird off the nest for more than 20 minutes because she regulates the

temperatures of her eggs - keeping them warm on cold days and cool on hot

days, just like insulation.

When Koppie reached the top, he reached into the nest and pulled out a

single egg, leaving two for the mother bird to incubate.

" The nest was still warm, " he said.

Eighteen minutes after the start of the climb, Koppie was back on the

ground. The mother bird flew back to the nest, and looked in over the side.

Ospreys typically lay from three to five eggs, but, most times, some of the

eggs or the young don't survive, said Barnett A. Rattner, an environmental

toxicologist with the U.S. Geological Survey and the lead investigator on

the team. The incubation period is 35 to 43 days, and then it takes another

55 to 60 days for the young to grow the feathers they need to fly.

The birds nest in South America when it is wintertime here, but their

nesting season is so long that they come back to Delaware in the early

spring.

Koppie wrapped the big egg flecked with brown splotches in a foam sheet and

placed it in a white plastic bottle.

Rattner and his team of research associates will check for eggshell thinning

and then take samples from within the eggs for signs of chemical

contamination. Over the next several months they will monitor the remaining

eggs, watching for the young to hatch, grow and then fledge.

Blood and feather samples will be taken to look for heavy metals such as

mercury and zinc and pesticides.

Collecting and analyzing the data will take months.

As Rattner talked, the male osprey flew overhead. A bottom-feeding catfish,

an afternoon snack, dangled from his talons.

" The Delaware River is most highly contaminated north of the Chesapeake and

Delaware Canal, and ospreys have been observed nesting there, " Rattner said.

" These birds are strictly fish eaters. All they do is eat fish. ... The

birds, even in the most polluted areas, are reproducing successfully. "

Still, there is concern.

" You think about an egg. It's a little container of fat, " Rattner said,

adding that many chemicals accumulate in fat. " What is in an egg is a good

indication of what they are feeding on in an area. Most of what is in the

egg is being accumulated locally. "

Reach Molly Murray at 856-7372 or mmurray

http://www.delawareonline.com/newsjournal/local/2002/05/22ospreyeggsteste.ht

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