COEUR d’ALENE — A recent report on dying tundra swans from the Idaho Department of Fish and Game discussed the potential for 2019 to be one of the worst years in terms of total death toll.
According to the report, IDFG staff have received numerous calls about dead tundra swans in the lower Coeur d’Alene River Basin, particularly around Harrison Slough.
The deaths are attributed to poisoning from mine waste contamination found in the wetland sediments where the birds forage, as well as seasonal weather factors that may have exacerbated the situation.
Annually, there has been an average of roughly 150 Tundra Swan deaths in the area. This year, the early body count is ahead of where it is usually at this time.
According to Kiira Siitari, a regional communications manager with IDFG, the previously released report was a warning that more deaths than usual could be expected, not necessarily that it was a guarantee.
“I can’t speak to total dead swans compared to previous years — the U.S. Fish and Wildlife Service monitors those numbers under the Migratory Bird Treaty Act. Working in the lower Coeur d’Alene River area, our Conservation Officers, biologists and sportsmen have noticed more dead swans, up to 60 at a time, in areas like Harrison Slough,” Siitari said. “The hypotheticals listed in the article are our best guess — there’s no scientific study that I know of in place to determine cause and effect of the number of swans that die each year.”
The hypothetical scenarios within the report ranged from timing and distribution of melting ice, water levels, as well as the length of time the swans stayed in the area.
Siitari explained each of the three hypothetical causes listed in the report
Concerning the timing and distribution of ice melt, “we had a snowy, cold February that locked most of the basin up in ice,” Siitari said. “As the swan migration picked up in March, most of the wetlands were still frozen and the areas that were open for birds to land and forage in were primarily in contaminated areas near the mouth of the river.”
The water level situation is the one hypothetical where the mine waste contamination really comes into effect, but not for any reason other than odd seasonal weather.
“It seemed to our biologists that many of the wetlands in the lower basin had less water than in typical years. A dry March or a slow runoff period may be the reason for this,” Siitari said. “Swans would avoid dry or frozen wetlands and target shallow areas in the floodplain with open water. Shallow water in contaminated areas creates a dangerous situation for swans because they can dig deeper into soils, where some of the most heavily contaminated historic mine waste sits.”
Swans feed on the roots and tubers buried in the wet soils, so the deeper they dig, the more pollutants are encountering.
That water level issue, paired up with the length of time the swans remained in the area pointed experts to their last hypothetical, but they can’t confirm these possibilities until the migration is complete.
“This is the most uncertain. Generally, the longer the animal is exposed to a toxin, the greater the chance of negative effects,” Siitari said. “There won’t be any comparison to past years until after the migration season is over and again, it will be out of U.S. Fish and Wildlife Service’s shop.”
Siitari did add that just because the numbers are higher right now does not mean that they will eclipse the usual average of Tundra Swan deaths.
“The swans may have died in a short period of time instead of spread out over several weeks — 60 dead swans is a lot more noticeable than a handful every few weeks,” Siitari said. “Or the way the ice melted congregated swans in very noticeable places (i.e. near highways, towns, fishing spots), so we and the public saw more than most years compared to others.”
Historically, the mining industry in Shoshone County had dumped their mine waste into the Coeur d’Alene River where they washed down the river and settled along the river bottoms, as well as in the marshy wetlands.
Efforts to reduce contamination exposure in tundra swans and other wildlife are led by the Restoration Partnership, of which Fish and Game is a partner.
In 2018, the partnership completed a comprehensive restoration plan that laid out a strategic framework for restoring natural resources, such as waterfowl, that are impacted by the release of historic mine waste.
Approximately $140 million is available from settlements to implement the plan.
These large-scale habitat restoration efforts have already begun.
Starting in 2006, the Restoration Partnership led a 400-acre restoration project on private farm lands near Rose Lake, providing clean marsh habitat for swans and other wildlife.
In 2015, Fish and Game habitat specialists restored another 65 acres of wetlands adjacent to this property in the Robinson Creek Project with funding support from the Idaho Department of Environmental Quality, U.S. Environmental Protection Agency and the partnership.
For more information, contact the Fish and Game Panhandle Regional office at 208-769-1414. More information on the Restoration Partnership can be found at www.restorationpartnership.org.