Hovering on the Edge of Existence
Captive breeding and a special refuge had begun to revive the Mississippi sandhill crane, which almost became extinct 30 years ago—then along came Hurricane Katrina
- Michael Forsberg
- Oct 01, 2005
WHEN HURRICANE KATRINA struck the Gulf Coast, it was one more challenge to the survival of a severely endangered species, the Mississippi sandhill crane. Among all endangered species, the most vulnerable are those that survive in small numbers living within a limited range. The crane is one of these creatures. Scarcely more than 100 remain in the wild, all on a national wildlife refuge named for them.
That refuge lies in southeastern Mississippi near Interstate 10, an area battered and drowned by Hurricane Katrina last August. Biologists have long feared that a single catastrophe, such as Katrina, might wipe out this sole surviving population of wild Mississippi sandhill cranes, rarest of six sandhill crane subspecies. The fate of these birds underscores the importance of protecting vulnerable species before they dwindle so severely that their existence can be swept away by a strong wind.
A plan during the mid-1970s to cut Interstate 10 across Mississippi and through the bird’s last core habitat in the southeastern corner of the state aroused the concern of Jacob “Jake” Valentine, Jr., lauded in crane circles as the father of the Mississippi Sandhill Crane National Wildlife Refuge. A decorated World War II veteran turned conservationist who died in early 2000, Valentine worked for 35 years with the U.S. Fish and Wildlife Service (FWS) in the Deep South and elsewhere.
The plan for I-10 created a cranes-and-lanes controversy that stalled construction and led NWF to initiate the first lawsuit under the Endangered Species Act of 1973 to go to federal court. A 1976 settlement designated 2,000 acres near an I-10 interchange as one of the first parts of the national wildlife refuge, established the year before to protect cranes and their habitat. The interstate was subsequently completed, and eventually the refuge grew to almost 20,000 acres of pine savanna.
Not long ago, before Katrina, I visited the refuge and the cranes, and saw firsthand what is at stake for the birds. From a modest blind woven into the pitcher plants and club mosses at the edge of a cypress swamp, I watched for two rainy days and nights as small groups of sandhill cranes came and went from a secluded roost under cold, gray skies. The birds arrived near nightfall, mostly in twos and threes, but a few larger flocks came in, too. The birds that arrived in small groups were mostly Mississippi sandhill cranes, dark gray and usually marked with multicolored leg bands. The individuals in the larger flocks were unbanded, lighter-colored and slightly bigger—probably greater sandhills belonging to a small population that winters here and nests in the upper Midwest. The birds made little noise as they arrived, and overnight in the blind I would hear nothing except the patter of light rain and the low growl of interstate traffic a half mile away. At first light, the birds would leave as quietly as they came.
North America is home to roughly 600,000 sandhill cranes divided among six subspecies, three that migrate (the lesser, greater and Canada) and three that do not (the Cuba, Florida and Mississippi). The species ranges as far north as the Arctic and as far south as Mexico and Cuba. It is among the oldest of all surviving bird species, with fossil records dating back at least 5 million years. But even though the sandhill crane is the most successful of all crane species, individual subspecies are not necessarily in good shape. The birds need an equal amount of grasslands and wetlands to survive, and many of the habitats upon which they depend are degrading or disappearing at alarming rates. The Mississippi sandhill crane and its dwindling homeland illustrate the challenges the birds face. Protecting them and their habitat is crucial. As Valentine once pointed out to one of his FWS colleagues, “These last wet pine savannas are beautiful, wondrous places, but without the cranes, they would have lost their soul.”
Historically, the Mississippi sandhill crane ranged across coastal Mississippi, Alabama, Louisiana and maybe into the eastern tip of Texas and the western third of the Florida panhandle. Its preferred habitat was wet pine savannas—vast expanses of grassy meadows with waterlogged, clay soils interspersed with tupelo-cypress bayou swamps—that lay wedged in a narrow swath between the rolling hills of the piney woods to the north and the brackish marshes near the Gulf Coast.
The soils in these soggy areas are naturally acidic and nutrient poor, unproductive for traditional agriculture other than grazing, turpentine production and logging. After World War II, however, timber companies converted the savannas into pine plantations, growing mostly slash pine, a fast-growing conifer that could be harvested for paper pulp. The timber companies destroyed many savannas, ditching and draining them. The companies also suppressed fire, a key component for maintaining the open-grassland savanna habitat. A dense, brushy understory choked the grassy meadows. Nevertheless, because change came late to the area, cranes were able to survive in this final stronghold into the 1970s despite the growing intrusions, Valentine said.
The pine-plantation industry was shortlived, and timber companies later sold off land for development. As the advent of air-conditioning and a higher post-war standard of living allowed more people to live comfortably in the hot and humid Deep South, land was subdivided, and new highways and interstates made once-remote areas accessible.
With the decline in natural habitat, the Mississippi sandhill crane population in the 1970s fell to fewer than 35 wild birds, giving the subspecies the dubious honor of being a charter member of the federal endangered species list. By 1975, the largest remaining tracts of natural pine savanna, and the few Mississippi cranes still left, survived only in the area that would become Jake Valentine’s new refuge. “The establishment of the refuge was absolutely critical to saving the crane,” says the refuge’s lead wildlife biologist, Scott Hereford, who once worked with Valentine.
The Mississippi sandhill population now stands at about 135 birds in the wild, with 25 breeding pairs on the refuge, up from five or six pairs when the refuge was established. In large part their recovery is due to a captive-breeding program that supported the largest and longest crane reintroduction project anywhere in the world. The program started at the U.S. Geological Survey’s Patuxent Wildlife Research Center in Laurel, Maryland, in the 1960s. Recently, the vast majority of captive-bred birds has come from the Audubon Center for Research of Endangered Species in New Orleans, Louisiana, the rest from the White Oak Conservation Center in Yulee, Florida. “The release program has been wildly successful,” Hereford says. “Lessons learned here can be applied in the conservation of other endangered cranes.” At the New Orleans center, a 21-year-old Mississippi sandhill crane died as a result of Hurricane Katrina and a second crane is missing, but all other birds are reportedly fine.
One of the biggest challenges for maintaining the refuge birds is chick mortality. Between the mid-1970s and mid-1990s, an average of only one chick annually survived its first year of life. In the past 10 years, average annual recruitment has increased roughly to three. However, that number is still far below the 10 to 15 birds needed to balance annual adult mortality. Refuge staff have had to supplement the wild population with yearly releases of 12 to 20 captive-raised birds. More than 90 percent of the adult birds breeding on the refuge today were captive-raised or are the offspring of captive birds. “Solving the natural recruitment problem is daunting, but we believe it can be done,” Hereford says.
Reducing predation is a major challenge. Predators such as coyotes, red-tailed hawks, bobcats, red and gray foxes, raccoons and domestic dogs are the main known cause of mortality among eggs, chicks, juveniles and released birds. Human changes on the landscape and the elimination of top natural predators like the wolf and panther have increased mid-sized predator populations, and predator control alone will never be enough to reduce their numbers.
Habitat availability is another factor that limits the crane population, so a long-term restoration effort is necessary to cut and burn vegetation and sculpt the refuge to restore degraded areas to wet-pine-savanna habitat. Many different units on the refuge need to be burned every two to three years to restore and maintain the open character of the landscape and to keep woody vegetation at bay. However, growing urbanization near refuge borders is making the use of fire increasingly difficult because of the very specific weather and wind conditions needed to keep smoke from adjacent roads and nearby neighborhoods. Still, in areas that have been managed with fire and other tools over the years, more of the former savanna continues to be restored. “Of course high intensity fires require complex operations, constant communication and consistent coordination to ensure safety and success,” refuge fire management officer Tony Wilder says.
Although the current crane population is only 130 to 170 wild birds with 30 to 35 wild breeding pairs, that small number is all that the refuge can support. The birds will always need to be managed intensively to avoid extinction. “One of the lessons from projects like this is for people not to wait until a population is nearly extinct in order to act, when lifesaving ‘emergency room’ type measures may be necessary,” Hereford says. The land will always have to be managed with fire, predator and invasive-species controls. The birds will always have to be monitored, and new captive-reared birds will probably always be released into the system to replace those that die. And there will always be the risk that one catastrophic event—disease or weather—could wipe out the entire subspecies in the wild. Katrina may be that catastrophe. At this writing, reports indicate that buildings at the wildlife refuge suffered some damage but are still standing. The fate of the cranes remains unknown, but Hereford says he believes that most probably survived.
Until we know for sure, I will recall the beauty of the cranes and of their native habitat with a certain anxiety. Could they have been destroyed? Did they fly off to some safer, higher ground? And if they flew off, to what habitat could they have gone—no other sanctuary has been left to them? I like to believe that most of the birds are fine and will continue life at the refuge, especially when I recall something Hereford said: “I’ve been to nearby degraded savannas that no longer have cranes, and there is a strange, mournful silence to the land. Let’s hope that doesn’t happen here.”
Prior to Katrina, crane enthusiasts had reason to hope the birds would be doing just fine this fall. On the positive side of the biological ledger, community support for the cranes and the refuge was growing. In the past, Hereford says, desperately low crane population numbers required that much of the refuge be off limits to the public, compounding the difficulty of building appreciation for and educating the public and local communities about the value of these birds and their habitat. Public and political support for the refuge suffered. Recently, perceptions and priorities were changing. “Local communities like nearby Gautier are seeing the value in nature tourism and are now working with the refuge to increase public awareness,” Hereford said before Katrina. “In the end, that community support is what we will need for this project to succeed.”
The local communities have been at least as battered as the cranes. As we wait to see how the Gulf Coast towns and cities will pull through and revive, we also wait to hear about the cranes. For updates on their status, go to our wildlife page, Michael Forsberg reports on Great Plains wildlife from Lincoln, Nebraska. For information about his book On Ancient Wings: The Sandhill Cranes of North America, go to www.michaelforsberg.com
NWF in Action
A Crane Ally
NWF has a long commitment to North America’s two crane species, the sandhill and the whooper. At about the same time as the Interstate 10 lawsuit (see story), Wyoming and the Basin Electric Power company proposed building a new dam on the Laramie River, a tributary of the Platte River. The Platte flows across Nebraska, where nearly half a million sandhill cranes, along with rare whooping cranes, congregate during migration to rest and feed. Recognizing that the dam would reduce already beleaguered water flows into the Platte, making central Nebraska less suitable for cranes, NWF sued Basin Electric Power. A settlement in 1978 provided $7.5 million for creating the Platte River Whooping Crane Maintenance Trust, which monitors, manages and restores crane habitat. Today, NWF and its Nebraska affiliate sponsor Whooper Watch, a program that engages volunteers to monitor the central Platte River for cranes. In Texas, NWF is fighting to protect freshwater flows into a national wildlife refuge that is critical to whoopers. For more information, go to www.nwf.org/ourprograms