Lead Poisoning From Fishing Tackle Still A Threat To Loons

Aug 18, 2016

While the calls of loons echo across many lakes in the region, it is not guaranteed to be something that you'll always be able to hear. The loon population has rebounded somewhat recently, but the birds are still at risk from many factors.

One of the biggest threats is lead poisoning. While several states have adopted laws banning certain types of lead fishing tackle in order to protect loons, the problem remains.

Harry S. Vogel, executive director and senior biologist at the New Hampshire-based Loon Preservation Committee, joined Vermont Edition on Wednesday to help us learn more about loons in general, as well as this lead poisoning threat and what's being done to address it.

An introduction to loons and their calls

Vogel first points out that loons are considered water birds, but they are not ducks.

"One of the fastest ways to really annoy a loon researcher is to call them ducks or waterfowl," Vogel says. "They're actually more closely related to the penguins and the tube-nosed swimmers, which are the albatrosses, the petrels and the shearwaters."

During the breeding season, loons can be found at freshwater lakes, but then they spend the winter season at the Atlantic Ocean, Vogel explains.

Loons are known for their calls – sometimes it sounds like a wail, other times more of a distinctive laughing sound. Vogel says that scientists have a "pretty good idea" as to what the different calls mean.

"One of the fastest ways to really annoy a loon researcher is to call them ducks or waterfowl." - Harry S. Vogel, Loon Preservation Committee executive director

For example, Vogel notes that the wail call usually happens when a loon sleeping on the water has drifted away from its mate.

"One or the other will wake up and they will give that wail call," Vogel explains. "That wakes up its mate and its mate then gives that return call and they come towards each other. So from those actions, from those behaviors, we infer that a wail means, 'Here I am. Where are you? And come closer.'"

The laughing sounds that loons make, known as a tremolo, has a different meaning.

"The tremolo is actually an alarm call for loons, so anything that causes a loon distress, you may hear that tremolo call," Vogel says.

However, he adds that it doesn't always necessarily mean something bad has happened to a loon making that sound.

"The tremolo is also the most dramatic statement of territory ownership that a female loon can make," Vogel explains. "And so sometimes male and female loons will kind of antiphonally call back and forth, tremoloing in the night, and that is essentially advertising territorial ownership of that body of water by a pair of loons."

The state of loons in Vermont and New Hampshire

While how loons are doing can vary from state to state, and even region by region, Vogel provided insight as to loons in the Vermont and New Hampshire area.

"In New Hampshire, I would describe the population as stable to increasing," Vogel says. "In Vermont, loons are doing better."

He attributes the loon population growth to the help provided by the public and organizations like the Loon Preservation Committee, as well as the Vermont Center for Ecostudies. They run the Vermont Loon Conservation Project,  headed up by loon biologist Eric Hanson.

"In New Hampshire, I would describe the population as stable to increasing. In Vermont, loons are doing better." - Harry S. Vogel

These groups do a number of things to help out loons, including monitoring the population by counting the birds, conducting research into threats and figuring out ways to minimize said threats, Vogel says.

An example he gives of their "focused management" is providing floating loon nesting rafts, which can aid loons that may have been displaced because of development or live on lakes with water levels that change quickly. Displaying signs and rope lines are other things they do to assist in protecting nesting loons, he says.

"Especially in New Hampshire and even more so in Vermont, loons are very intensively managed," Vogel explains. "And so the success that we've had has really relied on the management and the education and kind of a comprehensive conservation program that has been at work for many, many years in both of those states."

The threat of lead poisoning to loons

"So one thing that surprised us was was to learn that loons don't begin to breed, on average, until they're six years old," Vogel explains. "And then of course after that ... they'll lay a maximum of two eggs. And in New Hampshire and Vermont, typically a loon pair will have a chick every second year that actually survives to fledge from the lake."

Considering these patterns they've learned from their research, Vogel stresses the importance of simply keeping the birds alive year after year so they have more chances for breeding.

Lead fishing sinkers, like those pictured here, are a cause for concern when it comes to loon health. Vogel explained on Vermont Edition a couple ways loons can ingest these sinkers, which can cause lead poisoning in the birds.
Credit Jason Ganser / iStockphoto.com

"So anything that is affecting adult mortality of loons is something that we take very seriously," Vogel says. "And you don't need to go very much further than lead sinkers and lead headed jigs,  because in New Hampshire that fishing tackle, lead fishing tackle, is responsible for close to half of the documented adult loon mortality that we see. And in Vermont I think it is also approaching that level."

Loons' eating patterns make them susceptible to the threat posed by lead sinkers. Vogel explains that loons don't have teeth, so they swallow prey whole.

"After that, they forage along the lake bottom for these little pebbles and they ingest those pebbles," Vogel says. "They hold that in the gizzard, the muscular portion of their stomach, and the grinding action of those rocks, those act as surrogate teeth to grind up fish that they have just eaten."

As a result, Vogel says, what happens is that occasionally loons will mistake a lead sinker for a pebble and swallow it. Another way that's actually more common for lead to get into the loon's system is when a loon preys on a larger fish – one that may have previously broken an angler's line, Vogel explains.

"When they break that line, they're going to be trailing still a length of line and a lead sinker or a lead headed jig,” he says. “And when a loon gets that fish, it also gets the sinker or the jig."

Laws in effect

"New Hampshire actually became the first state in the nation to ban certain sizes of lead sinkers and lead headed jigs," Vogel says.

The legislation surrounding this has continued to build over time in the state, Vogel says – initially it only addressed sinkers and really small jigs.

"The legislation that is in effect in New Hampshire as of today restricts the sale and use of lead sinkers and lead headed jigs of 1 ounce or less in weight," Vogel says. "And we feel that that's a protective standard."

"The legislation that is in effect in New Hampshire as of today restricts the sale and use of lead sinkers and lead headed jigs of 1 ounce or less in weight. And we feel that that's a protective standard." - Harry S. Vogel

The standards for Vermont though differ from its neighboring state.

"In Vermont, I believe that it's a sinkers of a half an ounce or less, and no legislation really on lead headed jigs – and here in New Hampshire we've found that those lead headed jigs are responsible for more than half of the lead poisonings in the state," Vogel says.

He adds that they'd like to see the levels of protection rise in Vermont and in other nearby states in order to preserve the loon population in these areas.