Ducks have been dying – about five or six per day, sometimes more – in the ponds at Hagan Community Park.

Prompted by worried parkgoers, the city of Rancho Cordova is plunging into the monthlong mystery.

"Something's in the water," conjectured Scott Harmon, a frequent parkgoer who helped sound the alarm.

In the past few days, Harmon has been watching the birds die in the park's shallow ponds. On Sunday morning, he spotted a dead mallard floating in one pond, fetching it from the water with a branch.

He saw another bird floating – seemingly paralyzed – near the rim of the pond. Ordinarily, ducks fly off when spooked, but this one continued floating motionless, as still as a wooden decoy.

On a nearby tuft of tall grass, another duck drooped its neck, its wing feathers matted. Soon it was dead.

"They're dying, man, just kickin' it. Poor little guys. It's a horrible way to go," said Harmon, who had scooped out another dead bird from the pond the day before.

Slicks of algae cover much of the smaller ponds. At times, a stench drifts from the murky, stagnant water. At dusk, mosquitoes swarm.

The water looks nasty, it smells nasty.

A larger pond, popular with anglers, doesn't appear to have the same problems. Unlike the shallower ponds, a pump circulates its water.

Carolina Dave announced the crisis over the weekend on a post on Craigslist. There were ducks dying all over the little ponds, she reported. "What I saw there was horrifying," she wrote.

She tried to help one of the ducks during a family outing to the nearby American River.

She wondered if the same dangers to the park's ducks pose a threat to the people and pets that frequent the park – and to the students and teachers at Cordova High School, which adjoins the ponds.

"The ponds are right next to the school," Dave said in an interview Sunday. "There aren't any signs posted."

School officials weren't available Sunday.

The city's animal services office only recently learned about the duck deaths, and has yet to address the problem, said Kerry Simpson, the city's neighborhood services manager, who oversees animal services.

Among the initial steps will be performing necropsies on some of the ducks.

"It's too early to say what's going on," she said. "We've only just heard about it. We had no idea about the extent of the problem. Obviously, no one had reported it to us."

Groundskeepers at the park say they've been collecting a handful of dead ducks over the past month, and most of the ducks have been found on the shallower ponds near the high school parking lot.

The park is operated by the Cordova Recreation and Park District, and city officials will be conferring with park officials to determine what to do next.

"There are so many things in a duck diet, that it could be anything," Simpson said. "My biggest fear is creating a huge panic out there."

"We need to talk to the parks administrator," she said. "We'll be moving ahead as fast as possible."

Some parkgoers worry that the West Nile virus is killing the ducks – but that's unlikely because the virus isn't known to be deadly to such waterfowl as ducks, according to experts. Concern over West Nile usually centers on such birds as crows, jays and ravens.

"At this point, we don't know what's killing them," said Sharon Racine, an animal services officer who discovered a dead duck a week ago. She said she didn't learn about the extent of the problem until recently.

She described symptoms to a wildlife specialist – but no experts have yet visited the community park.

One theory, Racine said, points to botulism – the result of a naturally occurring toxin that can produce paralysis. "But it's pure speculation," she said.

It will take tests to determine the culprit.

"The water is pretty dirty, and ducks are bottom feeders," Racine said, explaining that the birds might be ingesting the toxins as they plunge into the muck for food.

"Maybe it will be a simple fix – flush out the ponds with clean water," she said.

Call The Bee's Bobby Caina Calvan, (916) 321-1067.