Attwater's Prairie-Chicken chicks are raised by the hundreds at the Houston Zoo and released to the wild. Despite these efforts, the wild population is not growing. Photo: Courtesy of Stephanie Adams/Houston Zoo

Conservation

Boom or Bust: The Last Stand of the Attwater's Prairie-Chicken

Each summer captive breeders release hundreds of the birds into Texan prairies—but few survive. Maybe, just maybe, this year they'll get lucky.

In springtime, you can hear the booming all the way from the parking lot of the NASA Johnston Space Center in Houston, Texas, where, tucked away from the spaceflight mission control center and moon-rock laboratory, an outdoor pen holds a flock of critically endangered chickens. The sound first registers as a vague thrumming on the breeze; come closer and it resolves into a pitched, resonant call, hollow and haunting as breath over a glass bottle, accompanied by the staccato drum of tiny, scaled feet on hard-packed earth.

The sound belongs to the Attwater’s Prairie-Chicken, a one-and-a-half-pound grouse with dappled brown and white feathers. (It's a subspecies of the Greater Prairie-Chicken.) In 1900, as many as a million of the birds ranged along the coastal prairies from the Gulf Bend of Texas and into Louisiana, where every spring the males gathered to dance and boom for female attention. Then, agriculture and development swallowed up 99 percent of the native grassland; droughts, storms, and invasive fire ants pushed the population to the brink. In 1967, the Attwater's Prairie-Chicken was listed as endangered under the Endangered Species Protection Act (the precursor to our modern Endangered Species Act). By 2002, the wild population sank below 50 birds.

These days it’s even lower. On August 25, 2017, the Category 4 Hurricane Harvey made landfall on the Texas coast. A record-breaking 60 inches of rainfall flooded out the bayous of Houston and swamped the surrounding countryside. At Attwater Prairie Chicken National Wildlife Refuge, a 10,528-acre remnant of native prairie 89 miles west of NASA, the waters rose so high that then-refuge manager Terry Rossignol found bundles of brush tangled atop the wire of the four-foot-tall cattle fences. Tramping along the puddle-soaked plains, his crew found first one drowned bird, then another. Before the storm, the wild population comprised 42 birds. Mike Morrow, the refuge’s ecologist, suggests that the storm carried off 80 percent of them. 

Two male prairie-chickens prepare for battle to defend their territory early in the morning at Attwater's Prairie-Chicken National Wildlife Refuge near Eagle Lake, Texas. Photo: Noppadol Paothong

“It felt like a kick in the teeth,” Rossignol, who retired earlier this year, recalls. “It was really demoralizing . . . It’s one of those things where you’ve got to go home and cry about it one night and get it over with, and then you come back and say: ‘Okay, things are going to line up next year.’”

It’s a feeling familiar to many who work with the Attwater’s Prairie-Chicken. For 26 years, a coalition of zoos, U.S. Fish and Wildlife Service officials, and private citizens have tried to salvage the remnants of the population. They’ve spent decades developing a breeding program—pairing up adult birds at NASA, and raising their chicks at the Houston Zoo before releasing them to the wild at the refuge—only to see many of their efforts falter due to a parade of bad luck. Which means the prairie-chicken is at the center of a very human story of frustration and hope, as the people tasked with saving it wrestle with a difficult question: What happens when you do everything right, and it still isn’t enough?

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ne of the things prairie-chickens like to do is dance. It’s a sunny day when I drive out to the breeding pens at NASA, a hot wind rolling over the green-gold grass, flowers the color of egg yolk clustering along the borders of the chicken wire. The prairie here is another remaining sliver of native grassland, and is a magnet for wildlife; deer lope by in the distance, and night herons primly stalk along the drainage ditches.

Hannah Bailey, the Houston Zoo’s curator of birds, unlocks the door to the breeding area and ushers me inside. On either side of a covered gravel walkway are two parallel rows of pens, 12 to a side, each holding a pair of chickens—the males conspicuous with their orange air sacs compared to the smaller, muted females. Despite the small facility’s location, it’s wholly operated by staff from the Houston Zoo, to whom NASA offered the land in 2005. It stands now as the zoo’s primary matchmaking spot for prairie-chickens, and the air hums with the sound of excited birds.

Most of the males are busy displaying in the dust as we come in. Their routines proceed according to clearly delineated steps: an aggressive cackle, a rapid, thumping tap dance, and then the boom—neck sacks inflating, pinnae feathers standing tall as rabbit ears. They glare at each other as they perform, and occasionally get into scuffles with neighbors through the mesh dividing each pen. The hens are more circumspect. Earlier in the season they would have come forward for a brief, flurried assignation if they liked what they saw; by May it’s late enough that most have mated, though a few examine the prospects with a critical eye. 

A female Attwater's Prairie-Chicken studies its romantic prospects at the NASA breeding facility this July. Photo: Scott Dalton

Like most captive-breeding efforts, the mated pairs are chosen deliberately. Every September before the breeding season starts, everyone involved in the program—including stakeholders from the refuge and the various zoos that raise prairie-chickens (Glen Rose’s Fossil Rim Wildlife Center, Caldwell Zoo, Abilene Zoo, and the Houston Zoo, which has the largest breeding facility of the bunch)—meet to take stock of the captive population and to decide which birds will be paired in the coming season. Birds are shipped to various breeding facilities in October, and they begin to work themselves up through competition by February. Mating occurs through April and May.

Convincing the birds that the captive-breeding facility is a worthy mating ground has taken some trial and error. Initially each breeding pen was visually walled off from the others with mesh blinders to stop the males from fighting. But zoo staff soon discovered problems with this approach. In the wild, prairie-chicken breeding is a rough-and-tumble affair, with males gathering in natural arenas called leks to display and tussle for the hens’ edification, working each other up through competition. Females choose the showiest and most impressive mates—one reason prairie-chickens are so ridiculous looking—and they tend to select carefully. The fertility of both sexes is intricately tied to this ritual. In the pens, however, the males couldn’t see each other, and so often failed to display; the females, unable to choose, often laid infertile eggs. The keepers solved the problem by removing the blinders, allowing the birds to see each other and better simulate the competition of the lek. Now, while females don't have quite as much free choice as in the wild—the keepers choose their partners based on genetic compatibility—the appearance of choice means their fertility has skyrocketed.

The catch, though, is that zoo staff have had to accept that male prairie-chickens will do their level best to beat each other up through the blinders. Once, Bailey says, she came in to find one of the males—subsequently dubbed “Frankenchicken”—badly beaten and limping around the wrong pen; they suspect that he snuck into the pen next door to fight with his neighbor. He was in bad shape—scalped, feathers bloody and askew—so they took him to the vet for stitches. He returned a conquering hero.

“Every hen that was around there was just standing at the front, like ooooh,” Bailey says, her voice fond. “They loved him . . . That’s the thing about the chickens; they’re so dang resilient.”

“It's amazing they can go through all of this and still boom."

Once the birds have mated, zoo staff pull the eggs as soon as they're laid, swap them with dummies, and drive them some 30 miles into downtown Houston, where they’re deposited in the zoo's incubators. They usually hatch after about 26 days, and the first room the hatchlings ever see sits in the back of the zoo’s bird facility. Gently humming machines line tables above white-tiled floors. Inside, rows of two-inch, fawn-colored eggs turn occasionally on rollers. A wine cooler used to keep developing eggs in stasis sits over in one corner.

There are about 500 eggs here, 60 or 200 to a machine, each carefully marked with genealogical information. When Bailey opens up the hatchling incubator, a gaggle of tiny faces bob into view. The day-old chicks are bouncy and restless—mottled brown-and-yellow balls of down that pop up and down, trying to see over the edge of the towel-lined containers. At a week old, they’re transferred into big metal tubs, where they zip around under heat lamps. After two weeks, they transition to outdoor pens behind the building. From there, keeping the fast-growing birds alive is mostly a matter of stopping them from killing themselves: They have a frustrating tendency to break their necks or concuss themselves by flying into the mesh. 

“If the chicks can injure themselves, they will,” Bailey says. “But we shoot for a survival rate of 75 to 80 percent [of all chicks that hatch], and we've met it many years.”

It’s when the birds leave the incubation centers that they start running into trouble. Over the past few years, Bailey and her staff have raised hundreds of chicks every spring. But many don’t get a chance to grow up—and few that do manage to successfully breed in the wild.

T

he process of releasing captive-bred birds goes in stages. First the months-old chicks are transported from the city to outside pens at the Attwater Prairie Chicken National Wildlife Refuge, where they get used to their surroundings. (Prairie-chickens grow fast, so the adolescent birds are generally capable of fending for themselves.) After about two weeks, the doors are opened and the birds are allowed out into the tall grass. The staff puts out food for a week or two, and eventually the wild birds wander off to start new lives.

In 1995, the first year, they released 13 chicks. Then it was 50, then 100. Now, the Houston Zoo alone releases 250 or 300 birds annually, with a few dozen more released by other zoos. (Most birds are released at the refuge; less than a dozen wild prairie-chickens survive on private land in Goliad County down the Texas coast.)

The growth of the captive-breeding program lies in stark contrast to the difficulty the partners have had in bringing that success into the wild.

When zoo staff first began releasing birds back onto the refuge in the 1990s, their chicks—the first wild generation—began turning up dead. Morrow, the refuge ecologist who collected the first wild Attwater’s Prairie-Chicken eggs to raise in captivity, and his colleagues would visit the birds’ favorite roosting spots and find little bodies dropped by what appeared to be starvation. “We couldn’t figure out why it wasn’t working,” Morrow says. Eventually, they found the culprit: invasive red fire ants, whose voracious appetites cleared the prairie of the small native insects the chicks depended on for food. (Although there’s now no way to prove it, Morrow suspects that the sharp declines in prairie-chicken numbers happened when the ants expanded their range into the coastal prairies in the 1960s.)

April Zimpel of the Houston Zoo carries a box containing Attwater's Prairie-Chickens ready for release. Photo: Scott Dalton

In 2014, the refuge began treating for ants, and released chicks were living longer. Those were good days, Bailey says: They’d worked out most of the kinks in the breeding program and things were looking up.

But they couldn’t control the weather. A long drought, followed by the 2015 Tax Day flood, the 2016 Memorial Day Flood, and then the 2017 juggernaut of Hurricane Harvey repeatedly decimated the wild population. The hurricane struck in the middle of the release season, with 249 birds on the ground. Perhaps 80 percent of the birds drowned, young and old alike.

There’s a name for this kind of run of bad luck, Morrow says: an “extinction vortex,” which is what happens when a species’ numbers drop so low that any setback potentially drags them closer to extinction. Things that could normally be absorbed by a healthy population spread across a wide geographic range—a direct hit from a hurricane or natural predation from owls and coyotes—suddenly become a matter of life or death, and attrition alone can drag a species down. The average survival rate for wild prairie-chickens, assuming everything goes well, is about 50 percent per year, Morrow says.

“So if you wipe out any gains from reproduction, you're going to see a 50 percent drop in your population every year,” he says. “When the population gets smaller and smaller, it's more likely that one of those otherwise relatively minor perturbations to the populations will pull it to the point of extinction."

It’s hard now to escape the possibility that Attwater’s Prairie-Chickens have simply been pushed too close to the edge. Climate change has contributed to a trend of stronger hurricanes on the Gulf Coast, with unhappy results for humans and animal alike. The marching concrete sprawl of Houston—which contributed to excessive floodwaters that native grasses would have sucked down—shows no sign of abating. Right now there’s quite a bit more native prairie left than there are chickens to fill it, but that says more about chicken numbers than the health of the prairie.

“We have amongst ourselves had discussions about [extinction],” Rossignol says. “What makes it tough is that if everything lined up perfectly for a couple of years, the birds would rebound. The chickens are a boom-and-bust species. They have the potential to drop dramatically from one year to another. They also have the potential to bounce up. Unfortunately, we’ve had a lot more bad years than we’ve had good years.”

He sighs. “It’s difficult to ask someone to put 20 years of their life into something and then say, ‘eh, call it quits.’”

Attwater's Prairie-Chickens in a temporary pen where they will be held for a few weeks before being released into the wild at the wildlife refuge. Photo: Scott Dalton

The thing to remember is that all population growth is slow to start, even with fast-booming species, Morrow says. You just need some breaks early on to get a toehold, and then things will start to move fairly quickly. There are plenty of possibilities for where the program can go next: putting birds on more private land, moving more aggressively against ants, continuing to tinker with captive breeding so that when a window of opportunity opens, they’ll be ready.

“I'm more confident now than I have been in 28 years that I've been working here that we will make some progress, if we can get some breaks on the weather,” Morrow says. “And we will . . . A lot of people think we ought to be able to snap our fingers and make it all better. But endangered species don't get into trouble overnight. And I think it's pretty naive to think you can fix it overnight, too."

The program itself has been incredibly valuable as an experimental laboratory for figuring out how to work with grouse, Bailey says. They’ve developed comprehensive guidelines for any institution interested in trying their hand at breeding Attwater’s Prairie-Chickens, and some have used it for related species, too. In 2014, Canada’s Calgary Zoo began a sage-grouse captive-breeding program after consulting with people from the Attwater’s program, and raised 50 chicks in their first year—in part because they didn’t have to start entirely from scratch. It’s a particularly impressive achievement given that most efforts to breed sage-grouse in captivity have failed

"People always ask, well, what if this doesn't work?” Bailey says. “And, you know, it might not.”

“You have to accept that as someone who works in conservation,” she continues. “But if it doesn't work, we've made so much headway in other grouse and prairie species that it's made a difference already in the world . . . It hasn’t been a waste.”

Out in the pens at NASA, the prairie-chicken males are still dancing the old dance, steps they come out of the egg knowing, its rhythm coded in their bones. They’ll dance it as long as there are hens left to watch; the hens will lay as long as there are males there to woo them.

The Houston Zoo team has a lot of work to do to ensure that future: chicks to release, anthills to treat, private landowners to negotiate with. After all, this might be the year that everything goes right.

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