On a cloudy, blustery day in early August, John Neill and two other Utah Division of Wildlife Resources biologists met at Farmington Bay — or what’s left of it. They piled into an airboat. It looked like a good vessel for cruising Florida’s Everglades or rolling through Bayou swamps, but not touring the Great Salt Lake.

The motor’s noise made thousands of birds take flight. There were Wilson’s phalaropes, moving together like shoals of fish in enormous waves. There were elegant American avocets, with bills like styluses and cinnamon-colored feathers from head to chest.

But for all the flocks fleeing, it was odd to see hundreds of birds feebly flapping their wings, staying stuck in the water. Even as a roaring boat blew right by, some birds sat perfectly still, their eyes wide and alert. Others had bent necks, their beaks falling toward the water, gently drowning.

Every now and then, the boat passed the carcass of an avocet or green winged teal, partially submerged, limbs stiff and feathers crumpled.

A dead duck floats in Farmington Bay on Wednesday, Aug. 5, 2015. By late August, around ten thousand birds had died of botulism on the Great Salt Lake during the summer. (Benjamin Zack/Standard-Examiner)

“We suspect it’s botulism, which typically shows up this time of year, when temperatures rise,” Neill said.

Tests have since confirmed an outbreak of botulism is, indeed, killing thousands of birds on the Great Salt Lake. It’s a paralyzing toxin produced by a bacteria that’s especially thriving this season in the bay’s shallow, warm, algae-filled water.

Neill works for the DWR’s Great Salt Lake Ecosystem Program and has conducted bird surveys on the lake each year since 2001. The lake’s at the lowest elevation he’s ever seen. In Farmington Bay, the water has dropped so low that an airboat is the only way to get around without getting stuck in the muck.

As the water keeps dropping, types of problems grow. It confines birds to a smaller area and incubates disease. Land bridges leave nesting birds vulnerable. Less water means concentrated salt content, which can disrupt the food chain. It puts an entire ecosystem at risk.

“If you look at maps from the ‘80s to early ‘90s, when the lake was all the way up, you’ll see a huge difference. The shrinking reduces all that surface area, the water habitat, and it limits where birds can go,” Neill said.

“That’s probably the biggest effect of the dropping lake, the reduction of habitat.”

John Neill, an avian biologist with the Utah Division of Wildlife Resources, looks over Farmington Bay during a stop on a bird survey of the southeast arm of the Great Salt Lake on Wednesday, August 5, 2015. (Benjamin Zack/Standard-Examiner)

The Great Salt Lake sustains around 7.5 million birds from 257 different species. Over half the continent’s eared grebes stop there. Around 20 percent of American white pelicans raise young there. More California gulls nest there than in any California colony.

Utah officials only began taking an organized interest in the lake’s bird habit in 1996, when the Department of Natural Resources began its first major waterfowl survey.

The surveys continue. Counting birds several times a year during different migration patterns helps state researchers understand how much impact a fluctuating lake can have on avian populations.

The botulism outbreak is one of the most visible blows. Less water means congested areas of hungry birds and more bugs carrying botulism. 

“Insects can pick up this toxin and concentrate it because they’re not affected by it,” Neill said. ”Then the birds end up eating the insects and it doesn’t take much toxin to affect their nervous system.”

That’s what keeps birds bound to the water and causes their heads to droop.

In the same way a filthy, urban environment contributes to the spread of human plagues, the disappearing water amplifies a feedback effect. A bird eats a bug infected with botulism toxin, the bird dies, then insects feed on the decomposing carcass, concentrating the disease.

American avocets feed in the shallows of Farmington Bay on Wednesday, Aug. 5, 2015. Around half of all American avocets in the world spend time on the Great Salt Lake during migration. (Benjamin Zack/Standard-Examiner)

Botulism isn’t well understood but it thrives in warm environments without a lot of oxygen. Several sewer treatment plants discharge wastewater in Farmington Bay. Around half of the water flowing into the bay is treated sewage, according to some estimates. That means it’s high in nutrients, which causes algae blooms that suck oxygen out of the water.

With duck season in full swing, wildlife officials are warning hunters to stay away from birds that appear sick.

“They’re probably the biggest users (of the lake) out here,” Neill said. “Botulism would probably be a bigger concern for them, or their dogs, at least.”

Botulism isn’t the only disease impacting the lake’s birds. On Sept. 8, DWR biologists confirmed a mallard was infected with avian flu at the lake. The virus doesn’t always make wild birds sick but it can grow in flocks, then easily spread and become fatal for domestic flocks like chickens and turkeys.

NESTING SITES EXPOSED

As Neill steered the airboat out of watery channels to the open water remaining west of Antelope Island, the survey crew spotted a coyote standing in puddle-deep water, near a span of exposed lakebed that now connects the island to the mainland. Those land bridges are another visible threat to bird habitat.

A coyote walks through the shallow waters of the Great Salt Lake about half a mile from the average shore of Antelope Island on Wednesday, August 5, 2015. (Benjamin Zack/Standard-Examiner)

Blue herons, gulls, double crested cormorants and pelicans all lay eggs and raise young on Great Salt Lake. They used to enjoy seclusion and safety on the lake’s islands. But at this point, no islands are left.

The drop in the lake’s depth means land bridges now lead to important nesting sites like Egg Island, Gunnison Island and Hat Island. There aren’t trees, so birds build nests on the ground. All kinds of predators, including humans, can now get to vulnerable eggs and chicks.

Nests make an easy meal for coyotes, skunks and raccoons. But it’s people that most worry Jolene Rose, a biologist at Antelope Island.

“You see people out there, walking out there,” she said. “If they go out and flush (adult) birds, others will come in and kill the baby birds and eat the eggs. If they’re pressured, they won’t return.”

Rose has tried posting signs on Lady Finger Point, a popular hiking area that now has a land bridge leading to Egg Island, but they don’t seem to be working.

“People get offended. They’re like ‘why can’t I go out there?’ A sign doesn’t tell you enough,” she said. “Unless you stand there, I don’t know how to deter them.”

While she can keep an eye on Egg Island, Rose is more concerned about islands that are remote, like Gunnison Island, which has the third-largest American white pelican rookery in North America.

“A lot of people ride ATVs in the West Desert, and they could easily ride in and go out to the island,” she said. “People love to investigate. People love to seen new spots. It’s part of our nature.”

Thousands of California Gulls and other birds gather on Egg Island, an important nesting site, in the Great Salt Lake on Thursday, May, 16, 2013. Since 2013, the lake level has dropped and dry ground now connects the island to nearby Antelope Island. (Benjamin Zack/Standard-Examiner)

'WHERE ELSE WOULD THEY GO?' 

Saline lakes harbor unique habitats, and birds have evolved to thrive in those specific environments. If the lake keeps shrinking, the water could become so salty it kills off all the brine shrimp and brine flies living in the water. That means losing food sources for millions of birds. And there aren’t many saline lakes like the Great Salt Lake left.

“Will (the birds) move, will they have to find new areas? I don’t know,” Rose said. “Because where else would they go?”

What’s happening to the Great Salt Lake is happening to saline lakes everywhere. Los Angeles water diversions dried up Owens Lake and nearly decimated Mono Lake in the Sierra Nevada Mountains. The Aral Sea in Central Asia has run almost completely dry. In Iran, Lake Urmia has been ruined and the region’s most charismatic bird, the flamingo, no longer visits. It’s partly from drought but partly a worldwide phenomenon of increasing human populations demanding more water.

Hundreds of white pelicans fly over the shallow water of Farmington Bay on Wednesday, August 5, 2015. (Benjamin Zack/Standard-Examiner)

At this point, Great Salt Lake’s Farmington Bay has been mostly reduced to a narrow channel, with salty playas, some mud flats and a few large, algae-filled ponds of smelly water only a few inches deep.

Neill estimates, so far, the botulism outbreak has killed between 10,000 and 20,000 birds. Farmington Bay has the majority of the sick birds, but thousands of ducks have become infected as they migrate to the area for the fall. Surveys found more infected birds around different parts of the lake in September.

During a banding trip to the Gunnison Island nesting site in July— the only time humans are permitted to access the area — biologists reported sightings of coyote scat, a molted snake skin and tire tracks.

During ecosystem surveys this summer, the supremely salty Gunnison Bay to the north lost any sign of viable brine shrimp, brine flies or the microorganisms that sustain them.

As a scientist, Neill speaks of the consequences in facts, registering little emotion — he’s possibly even quieter than the average bird biologist, which is saying something. But asked if he’s worried about the dropping lake levels, his voice surges. 

“Well, yeah,” he said. “It’s the amazing, the amount of shoreline that can increase as the lake drops. We’re seeing lots of changes.”

“There’s only so much habitat available for each particular bird,” he said. “And if we’re slowing taking that habitat away here, and slowly taking it away over there and elsewhere around the country, their population has to decrease as a result of that. It’s not enough for them all to survive.”

Contact Reporter Leia Larsen at 801-625-4289 or llarsen@standard.net. Follow her on Facebook.com/leiaoutside or on Twitter @LeiaLarsen

Explore the project

• We're losing the Great Salt Lake; Here's why you should care

• As Great Salt Lake dries up, Utah air quality concerns blow in

• Is drought to blame for drop in Utah's Great Salt Lake? Not likely

• Déjà vu: is Lake Urmia's demise a warning for Great Salt Lake?

• Why is the Great Salt Lake so smelly? That's a trick question

• Marinas in jeopardy as Great Salt Lake continues to dry up

• As Great Salt Lake shrinks, fate of nesting pelicans unknown

See what people are talking about at The Community Table!