By E. Donnall Thomas Jr.
On March 11, 1932, a farmer named James Green watched a drab, chicken-size bird vanish into the brush on Martha’s Vineyard, a small island off the coast of Massachusetts. “Vanish” is the right verb, for no one ever saw a living heath hen again.
During the Colonial era, the heath hen, a subspecies of the greater prairie chicken, was so abundant along our Eastern Seaboard that it became an everyday food source. Habitat loss, rather than hunting, led to the bird’s extirpation from the mainland by 1870, leaving only an isolated population on Martha’s Vineyard. Now that the heath hen has gone the way of the passenger pigeon, efforts are underway to conserve its fellow members of the genus Tympanuchus in populations that are not just viable but also healthy enough to sustain hunting.
Three varieties of prairie chickens endured after the heath hen’s demise: greater, lesser and Attwater’s. Native to limited areas in Louisiana and Texas, the Attwater’s prairie chicken was listed as endangered in 1967, and populations remain critically low today. Lesser prairie chickens also have sustained significant reductions in range and numbers. They were briefly listed as threatened by the US Fish and Wildlife Service in 2013, although that determination subsequently was overturned in court. They still are not legal gamebirds in any state. The only species available to hunters today is the greater prairie chicken (GPC), which is legal game south from the Dakotas through Nebraska to Kansas, with limited seasons in Minnesota and Colorado.
I recently spoke with Sarah Sortum (Calamus Outfitters), whose family ranch on the eastern edge of the Nebraska Sandhills dates back to the homestead days. Hers is a hunting family, and they outfitted hunts until recently, when they turned to ecotourism—with a heavy emphasis on prairie chickens—as a means of supplementing their ranch income.
While bird numbers are currently healthy on her ranch, she is concerned about the appearance of invasive trees, primarily eastern red cedars. Prairie chickens are birds of open grasslands, and their habitat makes them especially vulnerable to raptors. A study from the Oklahoma-based George Miksch Sutton Avian Research Center showed that avian predators accounted for a full third of GPC mortality. Trees and manmade vertical structures (more on that later) in places they did not exist historically provide vantage points from which raptors can hunt more efficiently. Prairie chickens avoid them, and hens will not nest nearby.
Sortum also notes the negative impact of fire suppression on prairie chicken habitat—a point Aldo Leopold made in regard to wildlife in general a century ago. In addition to clearing out invasive trees, fires promote the growth of forbs and insects crucial to the prairie chicken’s diet. Sortum’s family regularly conducts controlled burns on their ranch, and increased nesting activity in previously burned areas is obvious by the following spring.
In assessing the overall outlook for the GPC’s future, Sortum echoed the consensus of most biologists studying the matter. The reasons for contraction of the species’ historical range and the most significant threat to the birds’ future is disruption of large, contiguous parcels of native grassland habitat. Roads, agriculture and other forms of development don’t just leave the birds with fewer places to live. Habitat fragmentation isolates small populations of birds, reducing genetic diversity. As much as Sortum and her family have done for the bird population on their ranch, addressing this issue will require a larger resource base and more stakeholders.
Habitat disruption by oil and gas development has become a major concern for another important prairie gamebird: the sage hen. Currently, this problem is not as acute for prairie chickens, likely because their Midwestern range doesn’t contain as many fossil-fuel resources. However, disruption of grasslands by roads and development of any kind can negatively impact prairie chickens, so this could become a problem in the future.
I also visited with Jon Haufler, president of the North American Grouse Partnership and a prime mover in the formation of the Interstate Working Group—formed to provide a long-term approach to securing the futures of grassland gamebirds, including the prairie chicken. Haufler also stressed the importance of intact habitat. He estimates that a tract of 50,000 acres is necessary to maintain a healthy population of breeding birds but acknowledges that this might not be enough to ensure genetic diversity. That would require some degree of proximity between suitable tracts of habitat—ideally connected by smaller parcels of grasslands, so that birds could move back and forth on the ground.
Haufler also confirmed Sortum’s concern about invasive trees and manmade vertical structures, citing one study showing that just one tree per acre of grassland could limit GPC nesting success. While wind turbines have aroused concern, he was ambivalent about their impact on prairie chicken populations. Since GPCs are low-flying birds, direct collisions with turbines do not appear to be a significant cause of mortality. However, the birds’ instinctive tendency to avoid vertical structures could deter them from utilizing otherwise suitable habitat. He also referenced some studies suggesting that prairie chicken survival actually improved near some wind farms, possibly because higher-flying raptors were being killed by turbines in motion. At this time the net effect of wind farms on prairie chicken survival remains controversial.
Both Sortum and Haufler acknowledged the significant role that predatory birds and mammals play in prairie chicken mortality. However, neither felt that intensive predator-control programs were likely to be valuable in conservation efforts—at least in comparison to improved grassland habitat management. They also agreed that hunting as currently regulated poses no threat to GPC populations.
The prairie chicken is a “flagship” species for Midwestern prairie grasslands, just as the sage grouse is for the sagebrush steppe farther west. Both birds are iconic and charismatic, as anyone who has observed their spectacular spring lekking behavior recognizes. Neither deserves the heath hen’s fate. With thoughtful management, prairie chickens—along with other open-country grouse like sharptails and sage hens—should continue to challenge and delight upland hunters for generations to come.