CONCORD, N.H. – Biologists studying peregrine falcons in New England are elated that their numbers are rising, but concerned about a new threat they fear will reverse years of progress in rebuilding the bird population, and possibly harm people.

A study of falcon eggs that failed to hatch shows high levels of flame-retardant chemicals called PBDEs. Two samples found in unhatched eggs from a nest on Frankenstein Cliff in New Hampshire’s Crawford Notch State Park contained the highest overall concentration of the chemicals.

“I’d like to think we are getting the alarm out about this concern at a time when action can be taken, as opposed to waiting until the birds start disappearing,” said Chris Martin, a New Hampshire Audubon raptor specialist.

For a study published last spring, a group at the College of William and Mary in Virginia looked at 114 eggs collected from 35 nests in New England from 1996 to 2006. More than half came from New Hampshire.

The study reported unusually high levels of PBDEs, or polybrominated diphenyl ethers, commonly added as a fire retardant to everything from cars to furniture.

The discovery is a mystery because biologists haven’t found a contaminated food source for the falcons, said Robert Hale, a professor at the college’s Virginia Institute of Marine Science.

He said the PBDEs may not be the reason the peregrine eggs didn’t hatch – other contaminants also were found. But he said finding the chemicals is significant because scientists thought originally they were not getting into the environment, and the food chain, and because they still are being used.

Flame retardants save lives, Hale said, but more needs to be known about them, especially because they have been found in people, air, water and soil.

The Environmental Protection Agency is working with chemical companies to research the potential risks of chemicals including PBDEs.

Though there have been no direct toxicological studies on the effects of PBDEs on people, Hale said studies in animals suggest the chemicals interfere with the nervous system, thyroid hormone levels, kidney and liver function, fetal development and reproduction.

Two of three types of PBDEs have been taken off the market voluntarily, but one, called deca, which was used in the highest amounts, still is being used, Hale said.

Early studies suggested deca didn’t get into the environment or animals and that it did not alter its composition to resemble the more toxic varieties that are off the market, Hale said.

But he said more recent studies, including the work on New England’s peregrines, suggest scientists “missed the ball” originally by suggesting the deca variety did not accumulate in the environment.

“Do we fully understand the repercussions of that? No, because we don’t know how it’s getting in there. We don’t know whether the levels will continue to increase,” Hale said.

The laboratory studies require reaching into falcon nests to retrieve unhatched eggs. Sometimes it’s a long reach, as teams of biologists and climbers head to nests high on remote cliffs.

“In most places, we’re actually rappelling down the cliff to these nests,” said Martin, who coordinates the state’s peregrine monitoring efforts.

Once there, members put identification bands on chicks or recover eggs that failed to hatch.

A typical team in New Hampshire is made up of a biologist, spotters and climbers who are skilled mountain rescuers, including Paul Cormier of the International Mountain Climbing School in Conway and Michael Pelchat, manager of Mount Washington State Park.

“It’s a good team, when you’ve got good climbers who are looking out for our safety, and a biologist or two who are focused on the safety of the animals,” Martin said.

Looking out for the team can mean fending off dive-bombing falcons who, understandably, believe that people reaching into their nests are a threat to their young.

The teams found a record high 27 young this year in New Hampshire, but also collected nine unhatched eggs. Overall, the peregrine breeding population in the state has increased by 50 percent over the past decade.

Teams visited nine of New Hampshire’s roughly 18 peregrine nests this year, including one on the Brady Sullivan office building in Manchester.

“I don’t need a climber for that one,” said Martin. They reached the nest from inside the building.

On the Net

Only subscribers are eligible to post comments. Please subscribe or to participate in the conversation. Here’s why.

Use the form below to reset your password. When you've submitted your account email, we will send an email with a reset code.