The Washington Department of Fish and Wildlife is renewing efforts to to learn more about the deaths of trumpeter swans that spend winter months in Puget Sound.

Swan deaths are most commonly caused by lead poisoning but may also result from power line accidents in more developed areas like Kitsap County, according to the state.

This hunting season, the department  set up a hotline for hunters in the field to call and report any sick, injured, or dead swans they encounter.

“We’re trying to understand the sources and issues hurting the swans,” said Greg Schirato, deputy assistant director of the department.

State wildlife officials believe that lead poisoning in trumpeter swans is the result from the accidental ingesting of lead shot, which was banned in shotgun shells in 1991.

The spent shots are present in swan feeding and nesting areas from spent shot left by water fowl hunters.

There are no current reports of trumpeter swan lead poisonings in Kitsap County.

According to Schirato, swan fatalities in this region would more likely be caused by power lines. Specifically, swans could hit a power line as they fly to feed. Locals who see any of these urban mortalities can report them to the same hotline number.

Whatcom, Skagit and Snohomish counties are chief concerns this winter for lead poisoning. However, other hot spots may appear as calls from local residents come in.

“We have newer concerns like Grays Harbor as well. We are tracing the sources of lead poisoning down from the Canadian border,” said Schirato.

In all cases, residents should not attempt to handle or move the birds.

Since seasonal monitoring of swans began in 2006, the number of swan deaths due to lead poisoning has decreased approximately 65 percent in the most highly effected areas, according to the department press release.