Study Finds Mercury in Predator Peregrine Falcons

Study Finds Mercury in Predator Peregrine Falcons
In this May 16, 2018, file photo, an adult peregrine falcon circles near its nest on a ledge overlooking Lake Mead in Temple Bar, Ariz. Andrea Cornejo/Las Vegas Review-Journal via AP, File
The Associated Press

LAS VEGAS—A Nevada wildlife researcher has found that not even the fastest bird on Earth can escape mercury contamination.

The toxic element is turning up in feathers of peregrine falcons from coast to coast, including those at the Lake Mead National Recreation Area, state Department of Wildlife biologist Joe Barnes told the Las Vegas Review-Journal.

Over the past decade, Barnes has tested for mercury in 700 individual peregrines in southern Nevada, Washington, Maryland, and the Gulf Coast of Texas.

“Every single one of them was impacted, regardless of whether they live in wide-open desert or Lake Mead or Greenland or coastal British Columbia,” he said.

Barnes’ latest findings were published in February in the Journal of Raptor Research.

More research is needed to determine how much mercury peregrine falcons can tolerate, Barnes said. But studies of other raptors suggest concentrations of between 5 and 15 parts per million can significantly reduce breeding.

Barnes documented average mercury levels of 17 ppm in adult peregrines at Lake Mead near Las Vegas, and 23 ppm in adult peregrines along the Washington coast. Even falcons migrating south from remote Greenland, Alaska, and northern Canada, far from industrial pollution sources, carried about 10 ppm of mercury in their feathers on average, he said.

Peregrines are “one of the most impacted species when it comes to contamination,” Barnes said, because they feed on other birds that have been exposed to mercury.

The peregrine falcon dives on prey from above with wings closed, enabling it to reach speeds of more than 200 mph.

At Lake Mead, favorite peregrine prey is the eared grebe, a small water bird that migrates through the area by the hundreds of thousands.

Barnes said most grebes at Lake Mead also spend time in the mercury-laden waters of Utah’s Great Salt Lake.

Most human mercury exposure in the United States is by eating fish containing methylmercury, which forms when bacteria react with mercury in water, soil, or plants. Elemental and methylmercury are toxic to the nervous system, and inhaling mercury vapor can cause a variety of symptoms or even death.

So far, the falcons Barnes is studying show no ill effects from exposure.

Though mercury occurs naturally, Barnes said research suggests levels have increased by 300 percent since the start of the industrial revolution in the late 1700s.

“Peregrines are sort of the canary in the coal mine here,” he said.