“Kek!” - the call of the Yuma Ridgway's rail

Through collaborative conservation, a rare marsh bird thrives in the desert

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The hot, arid deserts of the Southwest may seem a strange spot for secretive marsh birds, but the Yuma Ridgway’s rail thrive in desert oases like Ash Meadows National Wildlife Refuge in Nevada. Credit: USFWS


By Peter Pearsall
July 28, 2020

On an incandescent July morning at Ash Meadows National Wildlife Refuge in Southern Nevada, University of Idaho graduate student Eamon Harrity and a field assistant sit along a berm of saltgrass and saltbushes beside a reservoir, fiddling with a Bluetooth speaker. The air is calm and rapidly warming; the dry-paper rustling of dragonfly wings and the drone of horseflies can be clearly heard over the clucking of coots from the reservoir. Suddenly the calm is disrupted by a series of grunt-like “kek” notes emanating from Harrity’s speaker. These are recorded calls of the Yuma Ridgway’s rail, and he hopes to pique the interest of one in the nearby marsh.

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An endangered Yuma Ridgway’s rail in the hand of a field assistant. Credit: USFWS

A chicken-sized, chestnut-colored bird with short wings and too-big feet, the Yuma Ridgway’s rail inhabits marshes and riparian areas from the American Southwest to northwest Mexico. Once widespread along the entire Lower Colorado River, the rail was listed as a federally endangered species in 1967 due to habitat loss.

The hot arid deserts of the Southwest may seem a strange spot for secretive marsh birds. At places like the Salton Sea in southeastern California, the Lower Gila River in southern Arizona, and Nevada’s Ash Meadows National Wildlife Refuge (managed by the U.S. Fish and Wildlife Service), triple-digit summer temperatures are common and rainfall is scant. But these sites are oases in the desert, providing year-round water to a diversity of wildlife, including endangered rails.

Back at Ash Meadows, by 11 a.m. the sunshine is glaringly bright, magnified by the albedo of the ash-colored soil. Harrity and his assistant have been playing the kek calls on the speaker for the past 20 minutes. A couple of birds have responded but none became bold or curious enough to approach. Harrity has set snare-like foot traps amid gaps in the dense cattail and bulrush, aiming to lure a rail with the calls.

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University of Idaho graduate student Eamon Harrity, right, and his the field assistant process a Yuma Ridgway’s rail. Credit: USFWS

At once, Harrity brings his finger to his lips. “Shhh...” A faint rustling comes from the cattails. Suddenly the rustling grows louder, more animated; Harrity springs into action and launches himself into the reeds. Several minutes later he emerges with a rail clutched to his chest.

He and the field assistant process the bird, taking morphological measurements, affixing an identification band to its leg, and attaching a telemetry “backpack” to track its movements. Afterward the bird is released, fluttering from the field assistant’s hand and disappearing seamlessly into the reeds.

Harrity’s research, conducted alongside his advisor Dr. Courtney Conway, has shed light on the habits of this elusive bird. It is the first study to definitively show that some of these rails migrate from breeding grounds in California and Arizona to spend winters in northern Mexico. Previously thought to be sedentary, some Yuma Ridgway’s rails travel hundreds of miles on these migrations, flying mostly by night and stopping frequently along the way.

The investigation into whether these rails migrate began at an unexpected place: solar facilities in Southern California. In 2013, biologists were confounded by the discovery of two dead Yuma Ridgway’s rails near solar arrays deep in the Mojave Desert. “One individual was found more than 30 miles from the nearest marsh habitat, which seemed very strange,” said Jennifer Wilkening, Service wildlife biologist and habitat conservation planning coordinator at the Southern Nevada Fish and Wildlife Office. “People wondered, ‘What was it doing out there?’”

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Eamon Harrity blows on the feathers of a Yuma Ridgway’s rail, checking for feather mites. Credit: USFWS

Solar facilities often feature dense arrays of solar panels which present a shimmering, water-like reflection from above. This so-called “lake effect” appears to confuse birds, which fly toward the reflection expecting water but finding nothing but dry desert. Some birds, disoriented and too exhausted to fly further, end up perishing.

No definitive research has been done to determine whether the “lake effect” is causing bird mortality at solar facilities, but some companies—including First Solar, Inc., which built the Southern California solar arrays where dead Yuma Ridgway’s rails first turned up—have taken preemptive measures to mitigate detrimental effects the facilities might have on wildlife and habitat.

One of First Solar’s measures is to help fund Harrity and Conway’s research into the migratory habits of these rails. Another is providing financial support to habitat restoration efforts at Ash Meadows National Wildlife Refuge, home to one of the most robust northerly populations of Yuma Ridgway’s rails.

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A field assistant examines a Yuma Ridgway’s rail. Credit: USFWS

Just west of Ash Meadows is the Amargosa River, a 185-mile-long riparian lifeline winding through the otherwise inhospitable northern Mojave Desert. Rails that flourish at places like Ash Meadows could follow that lifeline and colonize new territories, said Leonard Warren, Amargosa River project manager for The Nature Conservancy, which works with both private landowners and public land managers such as the U.S. Fish and Wildlife Service to conserve habitat for wildlife.

“These birds find forage and cover in dense stands of cattail and bulrush, and they build their nests on mats of these plants,” said Warren. But too much of this emergent vegetation decreases the value of marsh habitat for rails. Both cattail and bulrush are perennial plants that resprout from thick underground rhizomes. After each growing season, the leaves of both species die and form a layer of thatch above the rhizomes. If left undisturbed, these thatch layers pile up over the years, smothering other plant growth and decreasing the amount of open water available to wildlife.

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A Yuma Ridgway's rail is fitted with a telemetry backpack. Credit: USFWS

“No one fully one knows why, but periodically clearing that dense thatch layer seems to help these birds,” said Harrity. “In the Lower Colorado River, regular floods used to scour the riparian areas, clearing away that decadent emergent growth.”

Now, with all of the water modifications that have taken place on the river, those floods no longer occur, said Harrity. Land management agencies in the Lower Colorado region such as the Service have adopted prescribed fire as a surrogate to those erstwhile floods, clearing acres of thatch in a matter of hours. At Ash Meadows, fire is being implemented for the same purpose.

In February 2020, a prescribed burn at the refuge’s Lower Crystal Marsh—funded by First Solar and the Conservancy—cleared 152 acres of overgrown marsh vegetation to improve habitat for rails. Where cattails and bulrushes once grew in rank profusion, a fire-blackened shoreline now stands. Before the burn, the western shore of the marsh had been completely hidden from view.

Secretive rails won’t use this newly cleared habitat—not until the vegetation has a chance to grow back, but before it becomes too dense. “The ideal interval for these thatch-clearing fires could be three years, it could be five years; we don’t know yet,” said Carla Wise, senior wildlife biologist at the Southern Nevada Fish and Wildlife Office. “We’re hoping to find out what works best at Ash Meadows with this most recent burn.”

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A controlled burn at Ash Meadows’ Lower Crystal Marsh. Credit: USFWS

In the meantime, Yuma Ridgway’s rails continue to use other marsh habitat at the refuge and elsewhere in the arid Southwest, stalking shorelines and uttering their kek calls from the reeds. Habitat restoration efforts by the Service and its partners are part of a process ensuring that this seldom seen, oft-heard bird remains a unique component of riparian areas in the Mojave and Sonoran deserts.

 

Story Photo

Peter Pearsall

About the writer...

Peter Pearsall volunteered with the External Affairs office in Sacramento, California in the Spring of 2020. He now works as a Biological Technician for the Bandon Marsh National Wildlife Refuge.