Botulism blamed for tens of thousands of dead birds found along shore of Great Salt Lake

Botulism blamed for dead birds at Great Salt Lake

SALT LAKE CITY — Tens of thousands of dead birds are showing up along the shore of the Great Salt Lake.

The Utah Division of Wildlife Resources estimates 20,000 to 50,000 birds have died so far this year from avian botulism, a disease that periodically plagues birds at the lake.

Biologists say the outbreak ramped up in early August and is expected to last into the fall.

This year’s outbreak — which has left scores of ducks and avocets dead on shores and marshes — is considered moderate, said Leslie McFarlane, a state wildlife disease expert. A similar episode in 1997 killed more than a half-million birds around the lake.

The botulism bacteria is commonly spread when birds eat maggots from a dead bird that’s been infected.

Outbreaks are routinely reported across North America, and it’s not uncommon for thousands of birds to die. Cases tend to increase in the summer, when warmer temperatures and low-oxygen water provides a good environment for the bacteria to thrive.

Once ingested, botulism affects the nervous system, causing paralysis and often a slow death from starvation.

This year’s outbreak at the Great Salt Lake isn’t likely to put a significant dent in the millions of birds that flock there each year to breed, eat and rest during long migrations.

Dead birds this year have been found from Farmington Bay, on the lake’s southern end, to the Bear River Migratory Bird Refuge farther north.

Ron Taylor, manager of Antelope Island State Park in the middle of the lake, said he hasn’t seen any sign of dead birds along the island’s shore.

McFarlane says people shouldn’t allow their dogs to pick up dead birds found along the lake’s shoreline. A few years ago, several dogs were paralyzed — but later recovered — after handling ducks during training sessions with hunters.

An avian botulism outbreak at the Great Salt Lake in 1929 killed 100,00 to 300,000 birds. Another in 1980 killed about 110,000.