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Tuesday, October 27, 2020  Spokane, Washington  Est. May 19, 1883
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Outdoors blog

Swan deaths: annual spring disgrace continues along CdA River

Tundra swans are exposed to toxic lead during migration stopovers in North Idaho. (Kathy Plonka)
Tundra swans are exposed to toxic lead during migration stopovers in North Idaho. (Kathy Plonka)

ENVIRONMENT – I received the following email from a reader this morning:

Last Sunday my wife and I were riding our bikes on the Trail of the Coeur d'Alene's between Rose Lake and Harrison. Along the way, we saw what appeared to be a significant number of dead swans. I probably know the answer, but is it the heavy metals in the area that are the cause of their demise?

The Trail of the Coeur d'Alenes is a paved rail trail over a corridor used for a century to transport the produce of mining prosperity and its toxic aftermath. One of the benefits of the conversion to a recreational trail is that it  exposes more eyes to the issue of heavy metals pollution still lingering in the Silver Valley.

The saddest indicators are the carcasess of 150 or so tundra swans that die slow, agonizing deaths in our backyard during their migration stopover on the Lower Coeur d’Alene River.

It’s not a pretty sight, but your head's in the sand if you don’t see the carnage and the reasons for it.

Read on.

Weather along the swans’ migration route dictates how long they stay in the lower Coeur d’Alene River Basin before continuing their migration to Alaska.

A late spring such as we’re experiencing this year extends their stay and their exposure to the toxic levels of lead they absorb from contaminated sediment as they forage on roots and tubers in the marshes and lakes.

A century of Silver Valley mining and its waste didn’t bode well for life downstream.

If the great white waterfowl are here too long, the lead shuts down their digestive systems, causing the swans to gasp for air as food backs up in the esophagus and presses against the windpipe. The birds become emaciated and eventually starve to death.”

Federal research indicates that about 92 percent of the swan deaths along the lower Coeur d'Alene River are caused by lead poisoning.

About 80 percent of the wetland habitats have high enough lead concentrations to be lethal to swans, according to Idaho Fish and Game reports.

“People often ask why the swans are the only animals that die because of lead poisoning,” said Julie McKarley, Idaho Fish and Game Department conservation officer. “Unlike other species of waterfowl, swans dig down to get to their forage (tubers and roots) and in the process; they ingest more contaminated soil than other animals.”

Other wildlife succumbs to the heavy metals, but in an article written a couple years ago, McKarley described swans as “ big white beacons in a dull marsh. People notice them and their deaths more readily.”

What’s being done?

“The best way to reduce swan mortality caused by heavy metal contaminated sediment is to provide clean wetland habitats that have low concentrations of these contaminants,” she said.

“Ducks Unlimited, the U.S. Fish and Wildlife Service, the Environmental Protection Agency and others have recently begun working to restore some of the wetland habitat in the lower Coeur d’Alene River Basin.

But to date, the program has secured only a few hundred lowland acres to be flooded for attracting waterfowl migrations to healthier stopover habitat.

Nature is dying a slow death out there right now in our near perfect place to live.

Rich Landers
Rich Landers joined The Spokesman-Review in 1977. He is the Outdoors editor for the Sports Department writing and photographing stories about hiking, hunting, fishing, boating, conservation, nature and wildlife and related topics.

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