The Controlled Trickle that Saves Lives

Fifteen years ago I greeted spring by driving a mini camper through Heartland USA – Missouri, Kansas, Nebraska – and onto South and North Dakota, researching my book Rivers of Change.

Despite the occasional emotional criticism aimed at the US Army Corps of Engineers for having damned and channeled the Missouri River, I met and talked with bright, dedicated individuals – working for the Corps and for the US Fish and Wildlife Service – eager and determined to enforce the Endangered Species Act. And sometimes in magnificent ways.

Below is the chapter.

Chapter 22

FLOODGATES, TERNS AND PLOVERS

Before leaving the Lower Missouri River, I wanted a final briefing on the acrobatic duo so many riverside dwellers spoke about—the piping plover and least tern birds.

In a Corps of Engineer office adjacent to Gavins Point Dam in Nebraska, biologist Greg Pavelka sat before a spacious computer monitor. An adjacent Nature Conservancy calendar blasted an image of velvety wetlands.

Greg sat facing generous windows on the east wall. A set of binoculars mounted on a windowsill tripod aimed toward whirlpools near the base of the slate gray dam. Though a biologist, Greg’s reserved demeanor reminded me of an engineer from the Corps. His brown hair was clipped above ears. He hushed a light cough in his fist as though it might introduce an element of the unknown into our conversation. He was eager to talk about the endangered birds he helped protect.

The bird subspecies known as the interior least tern flocks to wilder segments of the Missouri River still lined with sandbars. During their journey, explorers Lewis and Clark categorized this bird as ‘frequently observed.’ In the nineteenth century the bird’s number diminished when its feathers and skin started adorning hats. In 1918, the Migratory Bird Act clamped down on this trade in avian plumage. But this protection did not last. After the Missouri River was confined to one channel the birds’ sandbar habitat was virtually eliminated. By the 1970s the population of terns dropped to twenty percent of its numbers during World War II.

Piping plovers flutter north to the Great Plains in late April, a month before terns glide in from the tropics. Males the color of sand stake out territory along naked sandbars that form lookouts against predators. From there they surge into rituals of courtship, displaying graceful and intricate overflights. After mating, birds stay united to defend their young. If a predator looms near their eggs, the orange-legged male will lurch onto the sand in a ruse, dragging one wing while moaning to distract the intruder. Biologists like Greg hope to prevent either plovers or terns from going extinct. If these birds are to survive in the long haul they need homesteads — sandbars. To grant them this, Reservoir Control engineers need to be able to create this habitat by letting more water spill downriver from Gavins Point dam; they need to allow at least one sizable pulse of water to roar through the river’s course every few years. Unfortunately, the very floods that create and maintain sandbars are those that the Corps is supposed to eliminate.

The result is that the river’s flow, regulated by upstream dams, only surges when some of that control is lost. Floods not only create sandbars; they clean them. Although the high water of 1997 cleaned vegetation off sandbars between Gavins Point and Ponca, weeds blossomed and covered these again. This created a problem.

“The birds like a little vegetation so chicks can hide,” Greg said. “But if there’s too much vegetation, they desert the area.”

Another high water pulse was needed to shave these sandbars clean again. But how to do this without waiting for a flood?

“Generally the river’s flood pulse has been eliminated,” Greg said. “That’s part of the reason the birds are endangered. They’re adapted to a system that changes, but now the system is more or less constant.”

The unchanneled section of the lower river that Dave and I canoed remains sprinkled with the sandy habitat these birds love. To protect terns and plovers there, they need to be monitored to ensure their eggs don’t vanish. Staff from the Fish and Wildlife Service and the Corps have developed a plan to accomplish this. During months when these birds visit the river, teams of biologists traipse along sandbars to record the location of each nest.

They then pass this reconnaissance intelligence onto Greg who pastes a summary of this data (including exact GPS coordinates) onto the Corps’ internal website. Greg pushed his coffee mug aside with the back of his hand. He rotated his computer monitor my way.

The sheet read: Threatened and Endangered Species Data Management System. He scanned the data.

“We’ve had a total of 112 piping plover nests so far this year: ninety-four hatched, fifteen destroyed, three —fate unknown,” Greg said.

“The crew surveyed from river mile 785 to 805 yesterday,” he added. “They’d observed twenty-three chicks. More than a hundred have fledged the river from near here.”

Even a small rise in the river level can wash onto a sandbar, flushing eggs downriver. Heedful of this danger, field teams note which nests sit within eighteen inches of shore. Greg then ‘red flags’ these waterside nests on his spreadsheet.

He tapped his highlighter against the monitor. The screen identified four nests perched along this foot and a half wide danger corridor at River Mile 839.5. Once Greg entered this data onto a spreadsheet, Bob from Reservoir Control inspected the figures, phoned Greg to get an estimate for when the last chicks would fledge, then fine tuned water releases from dams to protect each precarious nest.

This truth was refreshing and amazing. The distribution of millions of kilowatts of energy and the flow of over twenty cubic miles of impounded water depends, at times, on whether a single tern weighing less than a demitasse of espresso has flapped its wings and flown south in the direction of Guatemala. Until this final chick makes its departure, the interaction between dam flows, nest data, field teams and power output remains as coordinated as a four-chambered heart.

The day before, Reservoir Control wanted to increase water releases from South Dakota’s Fort Randall Dam. They phoned Greg to find out the status of all nearby birds. Greg retrieved fresh data from field teams on five nests near Niobrara bridge, then phoned Bob to discuss water levels.

“I told them if Lewis and Clark Lake stays at 1206 feet above sea level, it shouldn’t effect nests. It was at 1205.8 yesterday, so they’ll be watching their gauges.”

Based on Greg’s data, Reservoir Control then unshackled identical quantities of water from both Fort Randall and Gavins Point dams to maintain a steady level along Lewis and Clark Lake.

Within days, when the last birds fledged and headed south, Greg would let the engineers at Reservoir Control know.

“We’ll tell them the reach is clear—that they can change flows to their heart’s content.”

“Are there other threats to birds beside flow?” I asked Greg.

“Big things are weather and predators,” he explained. “Hailstorms, heavy rains. If a mink gets onto a sandbar, it could wipe out an entire colony. You also have avian predators—hawks, owls, gulls, crows. And there’s the possibility of human disturbance. These birds nest on sandbars. People with dogs can destroy nests without knowing it.”

“Their adaptation is camouflage,” Greg explained. “If disturbed, they freeze in place and try to blend in with the surrounding area. The idea is if you can’t see me, you can’t eat me.”

Greg turned a group of photographs over on his desk. White pebbles around the perimeter of one nest looked like rock salt on the rim of a daiquiri glass. Camouflaged eggs lay circled inside this ring.

“Nests are just depressions in sand,” he said. “Eggs are colored to blend in. In the old days a flood coming down the Missouri could wipe out a colony. The birds would then renest again because they’re adapted to a constantly changing system.”

When fall weather blows in, plovers flap as far away as Laguna Madre and the Caribbean isles while terns hightail it to the sunny Baja peninsula, Central America, and Venezuela.

Perhaps, Greg added.

Biologists were unsure exactly where birds went when they migrated. Such uncertainty is critical. “There’s a big emphasis on birds up here on the breeding grounds,” Greg said. “But one thing kind of overlooked is that they spend the majority of their lives, from nine to ten months, down in wintering grounds.”

In other words, the Endangered Species Act helps protect these visitors for the quarter of their lives they spend raising families on temperate U.S. terrain. Meanwhile in other countries smoking chain saws may be garroting their tropical rainforest homesteads. If the birds are to survive, other nations will have to recognize the need to protect them.