Atop Food Chain, Ospreys Ingest Many Poisons, Revealing Environmental Dangers

As apex predators, ospreys get a mega-dose of contaminants from their prey.

PITT MEADOWS, British Columbia—On an early spring morning, the Pitt River flows so calmly that the peaks of the Coast Range seem to admire themselves in its glassy waters. A motorboat lifts a wake, and the docks of the marina moan.

Standing on the riverfront dike, Sandi Lee quickly locates a soon-to-be mom.

"There's a nest in the scope," says Lee, offering a look.

John Elliott peers into the telescope. "What stage are we at?" he asks.

"Still sitting on eggs."

In her journal Lee notes who's home: Brown cap. Fierce yellow eyes. Dark necklace on a white breast. Bigger than its companion. A female osprey.

Elliott and Lee are spending a few hours on this river about 25 miles east of Vancouver counting the ospreys that have returned to lay their eggs. It's unglamorous but crucial legwork for the two scientists from Environment Canada.

Ospreys tell a story, and Elliott, Lee, and the other scientists who track the raptors are trying to decipher their message. For more than two decades in North America, particularly in the Pacific Northwest, ospreys have revealed disturbing tales about DDT, polychlorinated biphenyls (PCBs), pulp mill dioxins, flame retardants, stain-resistant compounds, urban runoff, mining wastes, prescription drugs, mercury, and more. (Related: "4 Videos: Threatened Birds Face Polar Bears, Poop-Sniffing Reporters")

The large birds are living repositories for chemicals: Perched at the top of their food web, they ingest all of the contaminants in every creature below them. As one chemical is banned, another takes its place in the environment. How do we know this? The ospreys tell us.

Masked, Mellow Predator

They live all over the world, up and down the coasts of every continent. "Just add water; you'll get ospreys," said Erick Greene, a University of Montana biology professor who studies them.

Also called sea hawks, ospreys are almost exclusively fishers, elegantly adapted to their occupation. With talons like fish hooks, they can dive from 200 feet up, hitting the water at 40 miles an hour to grab a meal. They are the only raptor that will completely submerge in pursuit of prey.

The osprey wears a black "bandit mask" around its fierce yellow eyes—most likely a smart evolutionary trick to counteract the water's glare. Yet they are remarkably mellow birds of prey—so focused on fishing that other birds can make homes in the underside of their nests, and rodents can seek shelter from hawks and eagles by living at the base of their snags.

They also tolerate humans well, and this has made them willing to inhabit some of the more polluted waters in North America, including the Columbia River and Chesapeake Bay. It also makes them easy to study.

"On I-84 going through the Columbia Gorge, there are nests within 50 feet of the highway where there is traffic going by at 70 miles an hour," said Chuck Henny, a research zoologist emeritus with the U.S. Geological Survey in Corvallis, Oregon.

The ultimate locavores, ospreys offer a precise gauge of contaminants released nearby and of chemicals that hitchhike to their habitat from thousands of miles away via winds and currents. Although they do migrate, they return to the same place, sometimes even to the same nest, to lay their eggs. As a result, their eggs and chicks offer Polaroids of pollution—snapshots of what's going on in the environment.

Poisoned Prey

The fact that we're seeing ospreys at all is a victory: DDT nearly wiped them out in the three decades after World War II.

Since then, new threats have emerged and old threats linger. Chemicals from manufacturing, pesticides, and everyday household items like furniture, plastics, cleaners, and pharmaceuticals pollute the natural world. For many of these compounds, the long-term impact on wildlife and humans remains a question mark. In higher doses, some have impaired the ability of birds to reproduce. Some may alter their ability to migrate. Studies of other wildlife have found that these chemicals can interfere with everything from the hatching of eggs to liver development in embryos.

An osprey hunkered in its nest can help tell us not only how much pollution is out there, but also how much it matters—for the osprey and for us. By the 1950s the raptor was one of our first indicators of damage from DDT, which thinned birds' eggshells, killing their embryos.

Osprey populations, along with those of eagles and other birds of prey, plummeted nationwide: In New England, 90 percent vanished between 1950 and 1975, wrote David Gessner in his book Return of the Osprey.

As a boy on a farm in Oregon, Henny, 71, remembers dusting his family's crops with DDT. "I didn't have a clue," Henny said of the poison he was spreading. Today he is one of the deans of osprey research in North America; he has spent a career studying contaminants in birds and mammals.

Such research has shown that DDT's legacy persisted for decades: In 1998, some 25 years after the pesticide was banned in the United States, Henny found that some eggs from ospreys nesting along the lower Columbia River contained the highest DDT concentrations of any ospreys in North America at the time, thanks to high amounts found in a fish they eat, the largescale sucker. The high levels were the consequence of both predator and prey living downstream of hundreds of miles of farm fields and orchards.

In most places, osprey populations had already bounced back, but the birds near the mouth of the Columbia still felt DDT's effects until around 2001, when that population finally seemed to recover, too, Henny said. Today at least 19,000 pairs are estimated to roost around the United States.

Ospreys also have recovered in Europe, after more than a century of persecution and accidental poisoning. During the 19th and early 20th centuries, they were shot or harvested in many European countries—and for a time were extirpated from Scotland, where their eggs were collected, according to the Global Raptor Information Network. Now there may be 11,000 breeding pairs in Europe, BirdLife International estimates.

It's mostly in the United States, though, where scientists are decoding the osprey's message about the health of the planet.

Code Red

Around Missoula, Montana, Greene has been using ospreys to help gauge the success of a massive Superfund cleanup on the Clark Fork River. Crews had scooped out decades' worth of toxic sludge that had accumulated from a gargantuan copper mine upstream, and Greene wanted to know how well the cleanup had worked.

He turned to ospreys, so many of which nest along the Clark Fork that the local minor league baseball team is named for them.

The cleanup was a success: Tests of osprey eggs downstream of the Superfund site found quite low levels of the "big five"—arsenic, copper, zinc, cadmium, and lead—targeted by the cleanup.

Then the surprise: Mercury levels in the eggs were through the roof.

Osprey chicks in Missoula had 300 micrograms of mercury per liter of blood. In humans, the guideline for pregnant women is 5.8 micrograms per liter, to avoid harmful effects on their unborn children.

"If you or I walked into the ER in a hospital and tested out with the level that these osprey chicks have in their blood, it would be Code Red," Greene said. "Above that [guideline] in humans, people have documented what's been euphemistically called 'cognitive dysfunction,' which basically means you get stupid."

In studies of many human populations, mothers' consumption of high-mercury seafood has been linked to reduced IQs in their offspring.

Does this mean the osprey chicks are stupid? That's an important question, but no one knows, Greene said. Young ospreys have to learn how to hunt on their own. They also have to be able to pull off the long and complicated road trip called migration. Soon, Greene hopes to put satellite transmitters on ospreys in high- and low-mercury areas to track them and gauge any differences.

In Montana, soon-to-be-published research by Greene and his colleagues has found "about 50 percent reduction in hatching success in high-mercury areas," which likely were contaminated by placer mining in the region. "There are very clear implications for human health," Greene said, as humans eat fish from the same waters. The data can help steer future state advisories about fish consumption.

The research also has particular relevance now as Montana considers shipping huge amounts of its coal to China. "The number one source of new mercury into the global ecosystem is from burning coal to generate electricity," he said. It would take two months for that Montana coal to get to China and about one week for its emissions to drift back over to Montana on the jet stream, he said.

It's a sad irony, Greene said, that we worry about mercury at home, only to possibly make a decision that sends more mercury our way.

Water Monitor

Back on the Pitt River, Elliott, a research scientist, and Lee, an ecotoxicology technician, walk up the dike, their eyes peeled for nests. The Pitt, before it joins the Columbia, is relatively clean and rural, its water issuing from a big mountain lake, an ideal place for ospreys to lay their eggs. They nest here every spring and raise their young before flying south for the winter. Every five years the scientists collect some of the eggs to test for contaminants.

Using ospreys as monitors started here in the early 1990s with another concern. Researchers were worried that pulp mills were poisoning the Fraser, Thompson, and Columbia Rivers with dioxins and furans, which are carcinogenic byproducts created when pulp is bleached with chlorine. For all their beauty, the Fraser and Columbia—the great rivers of the Northwest—are longtime dumping grounds for industry, smelters, paper mills, and farms (orchards and row crops).

Detective work that began with the discovery of a collapsed heron rookery soon spread to the monitoring of other birds, including osprey nests both upstream and downstream of the pulp mills. Research by Elliott and others found that embryos of ospreys and other birds collected near the mill sites had high concentrations of the contaminants. At the time, the contaminants didn't appear to affect either osprey hatching success or fledging of young. But a later study by another researcher found lower growth rates in nesting ospreys at a contaminated site when compared with an uncontaminated one.

These findings, among others, helped change laws: In 1992 British Columbia required industry-wide changes in the bleaching process to minimize formation of dioxins. Afterward, concentrations of those chemicals and related ones plummeted in osprey eggs and in fish downstream of the mills.

A newer concern is polybrominated diphenyl ether (PBDE) flame retardants, which have been used worldwide in household items such as sofa cushions and electronics. PBDEs, which can accumulate in human breast milk, may cause developmental problems in fetuses. As a result, the flame retardants have been banned in the United States and Europe.

Before the 2004 U.S. phaseout, PBDEs had been on the rise in the Columbia River system. One study had found a 12-fold increase of the chemicals in mountain whitefish, a favorite osprey food, between 1992 and 2000. To learn more, Henny and his colleagues turned again to the raptors.

The result was classic good news/bad news.

The bad news: PBDEs were everywhere. The scientists found them in all 120 osprey eggs tested from the Columbia, Willamette, and Yakima Rivers as well as Puget Sound from 2002 to 2007. Similar results were found in Sweden, Norway, British Columbia, and elsewhere in the United States. Also, in 2006 and 2007, a handful of eggs from both the Willamette River and the lower Columbia were found with PBDE concentrations higher than one part per million, which seemed to reduce the number of fledglings they produced per nest.

The good news: Concentrations of the flame retardants in osprey eggs seemed to crest between 2005 and 2007 and then decrease, likely in response to the phaseout.

Relatively little is known about the effects of PBDEs on ospreys and other wildlife, but research in lab animals suggests that high levels impair thyroid hormones, which are critical for brain development.

Besides PBDEs, scientists working to keep the Columbia River clean are also worried about an array of new pollutants. More than a hundred chemicals from everyday life were recently found in the street runoff and treated sewage that is discharged into the river system.

USGS scientists and colleagues have found dozens of contaminants accumulating in the river's sediment, including traces of endocrine-disrupting compounds, or contaminants that mimic or block hormones.

Are these pollutants having an effect? The researchers decided to examine the whole food web—topped by the osprey.

Key to their investigation were "prey baskets"—picture a garbage can that hangs around a nest, into which the osprey drops scraps. Scientists examined the contents to study largescale suckers, a fish that is the ospreys' main diet in the lower Columbia.

The results, published earlier this year, showed that concentrations of many of the contaminants—flame retardants, pesticides, PCBs—found in osprey eggs, as well as in sediment and fish, increased farther downstream toward Portland. In short, the more industrial and crowded the location, the more contaminated the wildlife and sediment.

Moreover, several contaminants in fish analyzed by the researchers exceeded the levels in state guidelines for human consumption. The findings will be used by Washington and Oregon health officials to advise the public on how much fish is safe to eat.

USGS research chemist Elena Nilsen credits the ospreys' messy garbage cans for enabling researchers to investigate these new questions. She said humans today are adding many contaminants, from cleaners to soaps to coatings, to the environment without understanding the effects on wildlife—or on ourselves.

Waves of Poisons

After counting ospreys at the Pitt River marina, Elliott and Lee drive a few miles upstream, to Addington Marsh, a wildlife area on Pitt Lake, the largest lake in the greater Vancouver area. It's an osprey bonanza: A stick nest as big as a wagon wheel sits on a piling every 200 yards or so, each with a female resident. Sometimes an expectant father hovers, looking useless.

As they walk, Lee makes notes in her journal and Elliott switches from quiet to passionate. Over the years he has watched as pollutants in ospreys have changed: first DDT, then PCBs, then PBDEs.

The only constant is that they keep coming.

More recently Elliott has been studying the role of perfluorinated compounds (PFCs)—chemicals used widely to make products stain resistant and to manufacture everything from nonstick cookware to firefighting foam. While these compounds aren't stored in fat like DDT is, it can take years for them to leave the body.

The results showed that concentrations of many of the contaminants found in osprey eggs, as well as in sediment and fish, increased farther downstream toward Portland.

In animal studies, some of these compounds have been shown to disrupt normal hormones, suppress immune function, and cause developmental problems in rodent fetuses, according to the National Institute of Environmental Health Sciences. Other rodent experiments suggest PFCs damage the liver and reduce the viability of embryos.

One of these compounds that has particularly worried Elliott and others is perfluorooctane sulfonate, or PFOS, which was used in Scotchgard until it was phased out by 3M in 2002. Five years later, in a study done along Maine's coasts and waterways, PFOS concentrations in three-quarters of osprey eggs exceeded a threshold for health effects in chickens. PFOS is a global issue: Osprey eggs from the Chesapeake Bay and the Delaware Bay contained amounts similar to those in eggs of other water birds in Japan and Norway.

What does this mean for ospreys? "For some of the newly emerging contaminants, a lot of those questions are still up in the air," said Chris DeSorbo, raptor program director at the Biodiversity Research Institute.

Little is known about how much of the PFCs birds can tolerate, and there is evidence that this isn't just a concern for birds: Elevated levels of perfluorinated compounds, including PFOS, are associated with kidney disease, lower testosterone levels, and other health effects in humans.

Elliott's long-term studies of three seabird species in the northeastern Pacific showed that a contaminant related to PFOS has increased steadily in all the birds studied, no matter whether they lived near the shore or at sea.

Just this month, findings in ospreys provided a warning about another newly emerging contaminant: prescription drugs, which are found in sewage discharge. A hypertension medication, for instance, was found in all 69 ospreys that were tested at the Chesapeake Bay. For several drugs, the scientists calculated that ospreys would exceed human therapeutic doses in just three to seven days of eating fish. Again, the effects on ospreys, or any wildlife, are unknown.

Elliott finds it all a bit exasperating.

"With all of these organic pollutants, every time you think it's just a matter of ushering this stuff out the door, letting it break down ... something new comes along," he says as he ends the day's work counting ospreys and walks toward the parking lot. It's hard to keep track of all the new compounds introduced into the environment, much less figure out their impacts, and it's challenging to keep the research going year after year, he says.

But keeping tabs on ospreys is important for their health as well as for human health, Elliott says. Tracking them, he adds, is "almost like a time machine." We can tell not only where we've been, but also where we're headed and, with luck, he says, we can change course in time.

Follow Christopher Solomon on Twitter.

The Winged Warnings series is produced by Environmental Health News, an independent, nonprofit news organization, and published in conjunction with National Geographic. Read additional stories in the series at EHN's website. Follow EHN on Twitter.

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