Avian Botulism Changes Balance

First fish were found, then dead birds started littering the waters and banks of Machado Lake.

Just as the outbreak peaked in mid-July, the mystery killer of hundreds of ducks, coots and other wildlife at Ken Malloy Harbor Regional Park was identified: avian botulism.

It left one of Los Angeles’ most diverse park habitats missing certain native and nonnative bird species.

After the worst die-off in at least four decades, park officials and advocates said they would recognize the effects of another botulism outbreak more quickly and thus be able to contain it better by treating the sick birds right away.

Although the outbreak solved the lake’s overpopulation problem, it also ruined this year’s breeding season, said longtime park advocate Mitch Heindel. Many native birds quit nesting when botulism started killing their young.

At Machado Lake, a combination of environmental and behavioral factors probably caused the outbreak. Namely, humans’ misguided belief that feeding ducks moldy bread is good for the birds, and the ducks’ unblinking willingness to accept a free meal.

To birds, Los Angeles looks like a big-box store parking lot: gray, expansive and with few open spots to park. Then there’s Harbor Regional Park’s 241 acres at Vermont Avenue and Pacific Coast Highway, across the street from Kaiser Permanente’s Harbor City hospital.

It is the pit stop of choice for migratory birds passing through Los Angeles, local Audubon Society founder Jess Morton said--and before the outbreak, for hundreds of feral ducks.

Not everyone sees the duck demise as a bad thing. Heindel, a member of the park’s advisory board, is glad many of the park’s nonnative ducks are gone.

The park’s master plan, which still must be approved by the city’s Recreation and Parks Commission, called for the removal of all nonnative birds. Removal, often a synonym for euthanasia, isn’t popular among Angelenos.

In 1993, efforts to kill 275 Venice canal ducks were stymied by public outcry. Twenty of those ducks, with human help, ended up in Machado Lake, Heindel said.

By this summer, the lake’s nonnative duck population had swelled to 300, helped by reproduction and the dumping of birds bought as pets.

That many birds on the lake ruins water quality, Heindel said. A single duck can produce a pound of excrement a day.

In addition, Machado Lake is fed exclusively by water from the Wilmington Drain, which collects most of the street run-off from surrounding neighborhoods.

Poor water quality, too much fecal matter, high temperatures and displaced silt can cause botulism outbreaks, said Jeannie Magis, rehabilitation manager of the International Bird Rescue and Research Center in San Pedro.

After the bacteria bloom, fish die first, she said. Then maggots carry the disease. Birds that eat tainted fish or maggots become infected.

The more maggots the birds eat, the sicker they get. They become glassy-eyed, droopy headed and then paralyzed, she said. Within a day, if untreated, the birds die.

Tim Hayes, the park’s recreation director, said it became apparent June 7 that something was wrong.

Wildlife scientists tested the water and took bird and fish corpses for testing. The water temperature in some places was 80 degrees.

For a month, Hayes and others waited for autopsy results as park workers tried to control the outbreak. The park never received the results because the specimens were lost, Hayes said.

Enter Magis, who immediately recognized the culprit.

By that time, most of the birds already had perished. Magis nursed a few birds back to health, but by then the lake’s eastern shore was home to more pigeons than native birds or ducks.

Despite poor water quality, Machado Lake remains a thriving habitat, home to about 325 bird species. With botulism dormant again, several problems remain. Improving water quality is a priority. So is educating people about the park.

Hayes said crews are putting up more signs warning people not to feed the birds. A bigger problem than children bringing bread crumbs to the lake are bakeries and tortilla factories dumping moldy bread on its shore, he said.

Heindel stood on the water’s edge recently, surveying what birds remained. He raised his binocular often, marveling at the variety of birds that skim the waters or nest in the reeds.

He acknowledged the lake’s shifted balance. The banks are emptier. Many birds have stopped nesting for the season, he said.