Swan deaths in Iowa offer lessons on the long shadow of environmental harms

The use of lead shot for waterfowl hunting was banned in Iowa in 1987 in an attempt to spare birds the agonizing effects of lead poisoning resulting from their incidental consumption of spent shot. It was the same year I was born and four years before a nationwide ban was instituted to reduce the long-documented impacts of lead poisoning on water-feeding birds like ducks, geese, and swans. Nearly four decades later, incidences of lead poisoning have declined, but some long-term impacts still linger.

This month, more than 20 trumpeter swans in southern Hamilton County died of lead poisoning (some were rescued and are being treated). While the exact source is unknown, it is quite possible the lead that doomed these birds was deposited prior to the 1987 ban. Scientists call this “legacy lead” because it persists in the environment, despite modern abatement efforts. It’s a reminder that the decisions we make today could have lasting implications for decades to come.

Swans, like all waterfowl, feed on vegetation, seeds, and insects in water as deep as their nearly 2-foot-long neck can reach. They don’t have teeth to start the process of digestion, so instead they ingest tiny rocks to go into a muscular part of their stomachs called a gizzard to help grind down the food. Sometimes, a lead pellet from a spent shot shell or a discarded fishing lure is mistaken for a rock, and the consequences are deadly.

Lead poisoning in wildlife is much more rare than it once was. Swans are much more common too. Eleven years after the lead shot ban went into effect, trumpeter swans reproduced in Iowa for the first time since the late 1800s. Since then, thanks to the hard work of dozens of citizen groups, county conservation boards, and the Iowa Department of Natural Resources, more than 2,000 swans have hatched. The most recent census estimates around 125 pairs breeding across the state.

The loss of nearly two dozen swans is a setback in their recent ascendancy and a humbling reminder of the long shadows that loom from past environmental wrongs. Shadows that lurk in more than just the sediments of lakes and the stomachs of birds.

Farmland soil from generations ago clogs our rivers and streams and is today estimated to contribute some 30% of the phosphorus that pollutes our waterways. Heat-trapping gases broken free from deep below the earth’s surface and combusted into the atmosphere threaten every aspect of life on our warming planet. Floods ravage communities as they rage downstream unrestrained by wetlands drained in Iowa’s first century of statehood.

The lesson to glean from these modern challenges is the importance of finding ways to do less harm today. Hunters, anglers, and shooters can use lead alternatives. Farmers, builders, and homeowners can keep the soil where it belongs. Everyone can emit less carbon and protect the water and greenhouse gas absorbing properties of grasslands, wetlands, and forests.

We all have a role to play to stop this cycle of environmental degradation that can help ensure kids born this year aren't cleaning up from the mistakes we make in their 37th.

Adam Janke is an associate professor of wildlife ecology and the wildlife extension specialist at Iowa State University. He lives in Ames. Contact: ajanke@iastate.edu.

This article originally appeared on Des Moines Register: Swan deaths offer lessons on the long shadow of environmental harms