One hour each year. Pretend that is the window of conception for your or your partner’s womb. Imagine the anticipation, the stress, the overcompensation. You know the hour will arrive in late winter, but never exactly when. Best to stay within shouting distance of your partner. Best to abandon your independent schedules and pursuits, be each other’s shadow instead, another way for two to become one.
I’m not sure we humans could manage species continuation under those restrictions. But prairie dogs do. A female’s estrus cycle, or the time when she can conceive, lasts about one hour per year.[i] Prairie dogs don’t understand how short a time this is—they live by instinct, having no expectations, and therefore no joys or disappointments, surrounding reproduction—but still, so much depends on a single, narrow hour. So much more than I thought possible.
On a summer day, I drive a four-wheeler across the pasture near my parents’ South Dakota ranch house, heading to a prairie dog colony. This is the land of my youth, and its familiarity drapes over me like a blanket. There is the cone-shaped butte covered with white yucca flowers; there is the flat stretch where my mare fell while chasing cattle and I broke my wrist; there is the two-tire dirt track leading to the dam; there are the barbed-wire fences I mended; there are the shadows of my former selves, from when my parents first took me out here in the pickup as a toddler to the day when, at age twenty-two, I stood on a hill and said goodbye to this land—all those shadows merge into the me of now, seven years later, cresting the hill overlooking a prairie dog town.
When we talk about prairie dogs, we usually mean the black-tailed prairie dog, the most common of the five species (the others being white-tailed, Gunnison’s, Utah, and Mexican prairie dogs). They are members of the Cynomys genus of the squirrel family, Sciuridae, which also includes chipmunks, flying squirrels, ground squirrels, marmots, and tree squirrels. The “dog” part of their name comes from their alarm call, which to early settlers sounded like a dog’s bark. French explorers called them “petits chiens,” or little dogs. Adults are about a foot long, weigh a pound and a half on average, and have tawny brown hair with a black-tipped tail.[ii] Picture a skinnier, tanner version of a woodchuck.
“Town,” another term used by early settlers, is how we describe a colony of prairie dog burrows, the conical mounds leading into them, and the network of tunnels underneath.[iii] Typical burrows are 16 to 33 feet long and 7 to 10 feet deep, but they can run up to 108 feet long and 16 feet deep. Prairie dogs build two types of burrow entrances: dome craters and rim craters. Dome craters are somewhat of a slap-up job; the dirt mounds are loose and unstructured, shaped roughly like a dome. Rim craters are higher and carefully sculpted from wet soil. One researcher described them as “miniature volcanoes.”[iv] The average town covers about half a square mile, or roughly 320 acres, and houses around 6,000 prairie dogs.[v] That sounds huge, but colonies in the past were often 50,000 acres or larger and millions of dogs strong.[vi]
Prairie dogs live in family groups called coteries. A typical coterie includes one adult male, two or three adult females, and a few male and female yearlings. Each coterie lives in its own territory or subsection of the town, spanning, on average, 0.8 acres. A coterie’s interconnected tunnel-and-burrow network never intersects another coterie’s. A casual observer like me won’t be able to spot individual territories, since the boundaries are rarely physical. It’s like driving through a planned suburban community—all the houses and streets look the same. Prairie dog researcher John Hoogland, who studied a colony in South Dakota’s Wind Cave National Park for fourteen years, noted where territorial disputes broke out and between whom—he’d marked many prairie dogs with numbers or symbols dyed on their backs—and could then map boundaries. Some territories were unchanged in size and shape the entire time.[vii]
I park the four-wheeler at the town’s edge and shut it off. A chorus of chirps rises into the evening. “Chirps” doesn’t begin to describe the intricacy of these sounds, which are the basis of one of the most complex animal communication systems in the world, perhaps more advanced than those of monkeys or dolphins. Con Slobodchikoff, who has studied prairie dog communication for more than thirty years, noted early in his research that prairie dogs used different alarm calls for each predator they encountered, and that “beyond identifying the type of predator, prairie-dog calls also specified its size, shape, color and speed; the animals could even combine the structural elements of their calls in novel ways to describe something they had never seen before.”[viii] In Prairie Dogs: Communication and Community in an Animal Society, Slobodchikoff and fellow researchers Bianca Perla and Jennifer Verdolin claim that prairie dog communication merits the term “language” (a word typically reserved for humans), since it meets twelve of the thirteen criteria for language.[ix] Based on Slobodchikoff’s experiments, I know that the prairie dogs will make a distinct and descriptive alarm call for me via unique tonal combinations, based on factors like my height and weight, what color clothing I’m wearing, how fast I’m moving, and what type of animal I am. The result will be something like: human short gray slow.[x]
For a while I gaze over the town, listening, taking in its expanse, watching the prairie dogs zip from mound to mound or stand on their hind legs and stare in my direction. I’m not here to witness the elusive reproductive hour—it’s June, and prairie dogs mate from February to April. And in any case, 98 percent of trysts happen underground, so they’re almost impossible to see.[xi] I’m here simply to watch the town dramas for an evening, to look at a place my former selves passed through countless times but never really saw.
A shadow of a former self:
I can’t remember exactly how old I was the first time I helped poison prairie dogs. Perhaps fourteen? Younger? The memory blurs. East of our ranch house, near a border fence with a neighbor, a town spread across a swale, a cancer in our cattle pasture. I remember it was an established town; a few of the holes were so wide and deep I could have fit inside, which is unusual since most burrow entrances measure about a foot across. My father armed me and my younger siblings with shovels and himself with a canister of aluminum phosphide tablets and a long tube with a funnel attached at one end. We approached the first hole, the four of us leaning on our shovels and peering inside.
My father snaked the tube down the hole and shook some tablets into the funnel. The tablets released poison gas into the tunnels and burrows below, killing the prairie dogs. Whatever else might be living down there—burrowing owls, badgers, tiger salamanders, or, unlikely but possible, black-footed ferrets—also died. On later trips we would pour water into the holes first to better activate the fumigant, but I can’t remember if we did that the first time. My father showed us how to fill the hole with dirt, packing it tight with the back of the shovel so the prairie dogs couldn’t dig out.
We trailed after him from mound to mound, shoveling and packing. The prairie dogs broadcasted their alarm call and raced into their holes as we drew closer. I don’t remember feeling anything about the prairie dogs—no death wishes, but no pity, either. Maybe my faulty memory has erased the day’s emotions, but it’s more likely that I really did feel nothing. Killing prairie dogs was just something ranchers had to do, the pervasive thinking went. A chore. A necessary defense of the land and our livelihood.
Later we came back—a few hours or the next day, I’m not sure—to see if we “got a good kill,” as my father would say. Many holes were undisturbed, which meant the dogs had likely died below. Dead ones sprawled across some of the mounds, having dug out and perished at the surface. I remember their eyes were squinted shut and their mouths were open. They seemed very small. I saw two badgers scampering through the town, presumably feasting on the corpses. The sun was setting behind the hill, and the town, bathed in a pale orange glow, was strangely quiet.
I lean into the memory, trying to see more, to feel more. But there is nothing left except my enduring remorse.
The info stamp on one of the photos I took that evening on the four-wheeler says 7:21 p.m., June 19, 2017. Two days from the summer solstice. The air rings with bird chatter and gray-green sage stands in clusters, for once untouched by wind, South Dakota’s most common weather feature. The sun will set at 8:42 p.m., but a bit of light will hug the horizon until almost 10 p.m.
I climb off the four-wheeler and walk through the town’s edge, still on my parents’ land. The prairie grass gives way to the clipped lawns around the outer mounds, though the transition is less stark than usual since western South Dakota is in drought. Weakened by decades of conventional livestock grazing, most of today’s grassland looks passable in wet years but withers during dry ones, which makes ranchers even more resentful of grass-eating prairie dogs. Across the fence is the Grand River National Grassland, public land where local ranchers like my parents run cattle under the direction of the US Forest Service. I slip between the strands of barbed wire, a glimmer of my childhood self in the movement.
Past prejudices, though, stay behind. I feel like I’m in on a secret about what the prairie dogs are up to out here, a secret hidden by 150 years of very bad PR. The prairie dogs don’t know this, though. Sentinels sound the alarm from their mounds. Human short gray slow! In flashes of tan and black they dart into their holes, then ease out to resume the warning cry when I’m a safe distance away. I’m not wanted here, but why should I expect to be? When humans come to town, death usually follows.
It wasn’t always that way. We used to recognize a certain kinship with prairie dogs. European settlers, never having seen these burrowing animals before, instinctively applied human descriptors to them: their colonies became towns and villages, their mouth-to-mouth style of greeting became kissing, their orderly societies became symbols of European-style civilization on what the settlers viewed as the otherwise wild Great Plains. In her article “Becoming a Pest: Prairie Dog Ecology and the Human Ecology in the Euroamerican West,” Susan Jones describes the many scientists, adventurers, settlers, and writers who, in the early 1880s when westward exploration was in full swing, employed similar language. The prairie dogs were “little yellow-brown personages,” “citizens,” and “neighbors” who lived in “populous republics.” They “communicate their reciprocal thoughts and feeling” via their expressive yips, and often “set out together on a walk . . . to visit some relations.” The prairie dogs created “streets and public places” and “well-regulated forms of government” within their “subterranean commonwealth.”[xii] The prairie dogs and their towns were everything the newcomers envisioned for the Great Plains. They were downright American.
Such complimentary images disappeared quickly, however. As Jones points out, prairie dogs and humans soon competed directly for land. “Both colonized, but in different ways,” Jones writes to explain the human and prairie dog ambitions at work on the plains. Settlers wanted to plant crops, dig irrigation ditches, graze livestock, and build homes and towns; the prairie dogs wanted to keep and expand their colonies. Prairie dogs also eat grass and keep the vegetation short within their towns, and this was an unforgivable sin in the eyes of ranchers, who believed then and now that prairie dogs compete with livestock and destroy the grassland. The prairie dog was branded as a pest, and our vocabulary soon reflected the change. By the late 1800s, the “rodents” were “evil,” their towns “infestations” and an “eyesore.” Western states passed pest laws targeting prairie dogs that in some cases forced landowners to poison towns. The Bureau of Biological Survey, the federal agency tasked with eradicating prairie dogs from public and private land, adopted the slogan “Death to the Rodents” in the early 1900s and sponsored large-scale poisoning campaigns that continue today under the direction of federal, state, and local agencies. People came to see prairie dogs as “animal weeds,” the agriculturalist’s nemesis, an attitude that persists today.[xiii]
Attitude: a settled way of thinking or feeling about someone or something, typically one that is reflected in a person’s behavior. I recall my teenage self working alone at a dog town on a summer afternoon. The leather gloves, the stainless steel poison canister with the twist-off lid, the skull and crossbones printed on its label, the wooden-handled spade, the sun on my neck. My settled ways of thinking and feeling about not just prairie dogs, but also land, agriculture, the natural world, humankind’s purpose—all of it reflected in the dropping of poison tablets into a burrow hole. Back then, the word “environmentalist” made me bristle.
I have both contempt and compassion for that self. Contempt because she’s so young and naïve, filled to the brim with dogma about all things ecological, social, religious, and historical. Compassion because in the coming years she will spit out that poison and try to find truth. The process will be humbling and painful, and it will weaken and even destroy some of her closest relationships. She will attempt to write her way toward truth, because for her that’s where it tends to reside, even if it isn’t discernible right away. She will come to understand that some truths are knowable and others will take a lifetime to comprehend, and still others she probably never will grasp.
A few knowable truths:
Two hundred years ago, the Great Plains supported more than 5 billion prairie dogs scattered across 11 western states, northern Mexico, and southern Canada.[xiv] They inhabited roughly 74 million acres, or 19 percent, of their 395-million-acre geographic range. Today’s prairie dogs live on just 1.2 million to 2 million acres, or 0.5 percent of their historical range. Their towns are small and isolated, and therefore vulnerable to poisoning and plague.[xv] Their population is less than 2 percent of what it once was.[xvi]
Recreational shooting (for fun and target practice) and a deadly rodent plague that first appeared in the United States around 1900 are partly responsible for the decline, as is urban encroachment and the rapid conversion of prairie and pasture to cropland. Poisoning by humans, though, is the primary reason America’s prairie dog population has fallen by 98 percent.
Our poisons are astoundingly lethal. Grain soaked with Compound-1080, or sodium fluoroacetate, was widely used from the 1940s on, until it was banned for use as a rodenticide in 1990. In prairie dogs, the poison’s typical mortality rate is 98 percent.[xvii] Journalist Faith McNulty sounded the alarm about Compound-1080 in her 1970 book, Must They Die? The Strange Case of the Prairie Dog and the Black-Footed Ferret. McNulty described the poison’s ability to kill well after an animal ingests a dose, whether via poison grain or via bait meat injected with Compound-1080 dissolved in water, a technique for exterminating predators like coyotes and wolves:
The most disastrous property of 1080, however, is its stability. It does not break down in the body of its victim, and this means that any animal or bird that feeds on the carcass of a 1080 victim may be poisoned, and its body may become another lethal bait. Furthermore, the dying animals vomit deadly doses of undigested meat, attractive to many animals and birds, wherever they go. Almost all carnivorous birds and small carnivorous mammals will eat carrion, so the possibilities of this chain reaction are extensive.[xviii]
The DDT-style chain reaction McNulty explains is one reason Compound-1080 was banned for killing rodents, since the poison caused wildlife population crashes throughout the West. Another reason is the horrifying way it kills: “Victims’ positions and conditions—including vomited lungs, distended veins, and evacuated bowels and bladders—show that animals poisoned by Compound 1080 die an agonizingly painful death. Deer who have accidentally ingested it have been observed trying to rip open their own bellies. Dogs appear to be driven insane by excruciating pain before they succumb to death.”[xix] Compound-1080 is still used to destroy coyotes and wolves, and dogs, birds, bobcats, and other meat-eating mammals are often unwitting victims.[xx]
Today we exterminate prairie dogs with oats covered in zinc phosphide, which also kills grain-eating insects, birds, and mammals. We also use two fumigants: aluminum phosphide tablets, like the ones I used growing up, and carbon monoxide gas cartridges, both of which kill nontarget species.[xxi] In the name of protecting livestock and crops, we “control” (read: poison) prairie dogs on public and private land, often using tax dollars and government employees and equipment, which McNulty calls “a form of subsidy for farmers, cattlemen, and sheepmen, relieving them of that part of their overhead.”[xxii]
But we have all played a role, even people who have never poisoned a prairie dog or lived on a ranch. We eat corn, wheat, and soybeans grown in plowed-up grassland that prairie dogs can’t inhabit. Enough of us support politicians who use subsidies and other financial incentives to entice farmers to keep plowing up native prairie. We buy meat raised by men and women who lobby for prairie dog “control” and take matters into their own hands when tax dollars aren’t enough. We live in cities and suburbs that push out most wildlife, especially animals like prairie dogs that build stationary dwellings. We keep expanding those cities. We refuse to put the prairie dog on the threatened or endangered species list, even when doing so would also protect critically endangered species like the black-footed ferret and the burrowing owl. We are a society that largely supports conservation, but lacks the collective will to act.
Truth. My search for it has led me here, to a dog town on the Grand River National Grassland on a summer evening. I crouch next to a burrow, wanting a prairie-dog’s-eye view. The truth, as I once saw it, was that the prairie dog is nothing but a pest. Then I turned that truth over in my mind, as I would turn a stone in my palm, inspecting all sides, searching for flaws or unseen worth, only to discover that I held not a gem, but a fake. Like David Foster Wallace, I’ve considered the lobster, and I’m not at all convinced we humans are the best judges of a creature’s worth or its right to exist.
So often we judge wrongly or accept myth as fact, as we have done with regard to the complex ways in which prairie dogs and livestock interact. Research shows that while prairie dogs and livestock do eat many of the same plants, the competition is, overall, mutually beneficial for them and for the land. Is the grass shorter inside prairie dog colonies? Yes, but it is also more nutritious—higher in protein and more digestible, with fewer woody, unpalatable plants like mesquite. That is especially true in younger colonies and at the edges of older ones. Researcher James Detling found that the burrow mounds, which ranchers bemoan because of the exposed dirt, account for just 6 percent of a colony’s surface area and “thus represent a small loss of available forage to livestock. On the positive side, plant species such as western wheatgrass, buffalo grass, and scarlet globemallow sometimes grow well on, or at the periphery of, burrow-mounds.”[xxiii] Even though the burrow mounds slightly reduce available grazing acres, prairie dogs make the remaining land more nourishing and diverse in plant species.
In fact, according to Hoogland, “livestock commonly prefer to feed at colony-sites, so that the net effect of competition is less than what might be expected simply from the amount of forage consumed by prairie dogs.”[xxiv] Many other researchers make similar claims about the prairie dog’s impact on livestock and the grassland. In one study that assessed the prairie dog–cattle relationship, scientists found that
despite prairie dogs occupying only 12% of the landscape, cattle associated with colonies more than 24% of the total time; whereas, while annual grasslands covered 50% of the total area, cattle utilized them less than 20% of the time . . . Prairie dog colony edges were preferentially selected for grazing by cattle across all seasons and were the most utilized foraging zone during the winter season. More than 50% of the grazing events occurred in only 7% of the total experimental area, being represented by the colony edges.[xxv]
The idea that prairie dogs are bad for livestock production—a claim repeated so often that it has hardened into fact—melts into myth after a closer look. So does the notion that livestock step into burrow mounds and break their legs, another fear I heard growing up. Hoogland writes that
Over the years, I have chatted with more than 100 ranchers in Colorado, South Dakota, and Wyoming and have asked about broken legs. All the ranchers fretted about leg fractures, but only one could muster an example: a cow that sometimes foraged in a field with prairie dogs somehow sustained a broken leg . . . The implication is that the frequency of leg fractures from prairie dog burrows is trivial—probably because conspicuous dome and rim craters render burrow-entrances easy for domestic livestock to avoid.[xxvi]
One last truth, and it’s a difficult one: ranchers are sometimes directly responsible for the spread of prairie dogs on their land. Prairie dogs love to colonize areas with short, sparse grass, and most ranchers have created the perfect environment for prairie dogs by relying on conventional grazing. Under conventional grazing, ranchers turn livestock out in large pastures for a long period of time. The livestock overgraze choice plants while leaving others untouched; they move slowly without aerating the soil or trampling dead plants so new ones can grow; and they tend to stay near water rather than grazing uniformly and depositing manure evenly across the land. The cycle continues until woody plants and bare ground overtake grass and herbaceous plants.
Why does this happen? American grasslands evolved in response to large, tight herds of bison that moved constantly to avoid predators and find fresh grass. Bison didn’t graze in a leisurely fashion, as today’s conventionally managed livestock do; they ate almost everything in front of them quickly and moved on, churning up the ground and smashing dead plants as they went, and fertilizing the land uniformly. They didn’t return to the same area for a long time, which gave the land plenty of time to recover. Today we call this high-impact, short-duration grazing—but conventional grazing is low impact, long duration. Under the latter conditions, prairie grass dies, and prairie dogs can spread quickly without the thick ground cover that once kept their towns in check. We know that system worked because prairie dogs historically occupied just 19 percent of the acres within their range. They didn’t spread, virus-like, and they didn’t crowd out other species or destroy all the land.
In fact, the prairie dog is a keystone species—a species that has significant, unique effects on its ecosystem that are disproportionately large relative to its abundance.[xxvii] It is also a foundation species, or one that creates and defines an ecological community or ecosystem by being locally abundant and regionally common, by creating steady conditions required for other species to thrive, and by stabilizing important ecosystem processes.[xxviii] These two classifications, keystone species and foundation species, help explain why the grassland thrives when prairie dogs are present: they prop up other species as well as their surrounding environment.
What does being a keystone species and foundation species look like for the prairie dog? In a word, partnership. The black-footed ferret, now one of North America’s rarest animals because of the prairie dog decline, evolved alongside prairie dogs and cannot exist without them. The black-footed ferret eats a practically prairie-dog-only diet, which is convenient since it also lives and nests in prairie dog burrows, as do badgers, rattlesnakes, and tiger salamanders. Prairie dogs also make the land more habitable for certain animals. Birds such as mountain plovers, burrowing owls, and horned larks prefer the clipped landscape crafted by prairie dogs. Large grazers like deer, antelope, and bison gather to eat the nutritious grass. Wolves, now eradicated from the prairie by humans, showed up to eat those grazers as well as the prairie dogs; today, animals such as hawks, coyotes, foxes, bobcats, and the occasional mountain lion do so. Prairie dogs aerate and mix the soil by burrowing, which positively affects the nutrient and water cycles, and they fertilize the topsoil with their waste. All kinds of underground life flourish because of their influence, too.[xxix]
The prairie was once America’s most expansive ecosystem—an environment that will disappear in my lifetime if current land usage and climate change trends continue. That’s what depends on a lone hour of prairie dog procreation.
My shadow lengthens. It’s time to get back on the four-wheeler and drive home, where I won’t be able to talk much about my visit to the dog town. That’s okay. I don’t know what to say about my little pilgrimage yet. I sense there’s much to learn. It’s humbling, studying animals. What do I know about the grassland that a prairie dog doesn’t?
Prairie dogs seem to have things figured out. What if human cities were more like their towns—habitats instead of environmental dead zones? What if we limited how much land we used, as the prairie dogs did in their heyday by occupying only a small fraction of their range? What if humans acted more like a keystone species or foundation species, working for the overall good instead of just our own? What if we saw ourselves as part of the natural world instead of as something separate from or dominant over it? What if we not only remedied the damage we’ve done, but also reshaped our actions going forward?
Perhaps the answers, or some clues anyway, have been right in front of us the whole time, not just in prairie dogs but in all of the natural world. Balance isn’t new. The interconnected web of species isn’t new. We’ve been taught to believe those things don’t matter and are even harmful to human progress. The truth inside a prairie dog town won’t stay hidden forever, though. I have to believe that to avoid despair, to feel any kind of optimism in the face of climate change and disappearing ecosystems.
The land of my youth passes by in sage and birdsong, cut banks and creeks, a pair of antelope racing over a hill. There is the cone-shaped butte, the memory of a broken wrist, a dirt track, the barbed wire. The shadow of a shovel and a steel canister. I feel the past but do not stop. Those hours are over. Instead, I move forward and hope there’s still time.
[ii] John L. Hoogland, “Social Behavior of Prairie Dogs,” in Conservation of the Black-Tailed Prairie Dog: Saving North America’s Western Grasslands (Washington, DC: Island Press, 2006), 7–12.
[iii] Susan Jones, “Becoming a Pest: Prairie Dog Ecology and the Human Ecology in the Euroamerican West,” Environmental History 4.4 (1999): 535.
[iv] Hoogland, “Social Behavior of Prairie Dogs,” 20.
[vi] Jonathan Proctor, Bill Haskins, and Steve C. Forrest, “Focal Areas for Conservation of Prairie Dogs and the Grassland Ecosystem,” in Conservation of the Black-Tailed Prairie Dog, 236.
[vii] Hoogland, “Social Behavior of Prairie Dogs,” 17–21.
[viii] Ferris Jabr, “Can Prairie Dogs Talk?” New York Times Magazine, May 12, 2017, https://www.nytimes.com/2017/05/12/magazine/can-prairie-dogs-talk.html.
[ix] C. N. Slobodchikoff, Bianca S. Perla, and Jennifer L. Verdolin, Prairie Dogs: Communication and Community in an Animal Society (Cambridge, MA: Harvard University Press, 2009), 85–87.
[x]Ferris, “Can Prairie Dogs Talk?”
[xi] Hoogland, “Social Behavior of Prairie Dogs,” 21–23.
[xii] Jones, “Becoming a Pest,” 534–38.
[xiii] Jones, “Becoming a Pest,” 538–45.
[xiv] Hoogland, “Social Behavior of Prairie Dogs,” 1.
[xv] Proctor, Haskins, and Forrest, “Focal Areas,” 234.
[xvi] Proctor, Haskins, and Forrest, “Focal Areas,” 232–34.
[xvii] Steve C. Forrest and James C. Luchsinger, “Past and Current Chemical Control of Prairie Dogs,” in Conservation of the Black-Tailed Prairie Dog, 122.
[xviii] Faith McNulty, Must They Die? The Strange Case of the Prairie Dog and the Black-Footed Ferret (New York: Doubleday & Co., 1970), 18.
[xix] Here “dogs” refers to domestic dogs that accidentally ingest Compound-1080. See “Two Killers That Need to Go: Fact Sheet,” PredatorDefense.org., June 4, 2017, https://www.predatordefense.org/docs/wildlife_poisons_fact_sheet_6-4-17.pdf.
[xx] Sodium cyanide, loaded into spring-activated devices or “bombs” called M-44s, is another dangerous poison used to kill predators that also murders nontarget wildlife and dogs. People walking their dogs outdoors have stepped on M-44 bombs; pets have died, and people have been sickened. Both M-44s and Compound-1080 are especially dangerous for children.
[xxi] Forrest and Luchsinger, “Past and Current Chemical Control,” 132–35.
[xxii] McNulty, Must They Die? 11.
[xxiii] James K. Detling, “Do Prairie Dogs Compete with Livestock?” in Conservation of the Black-Tailed Prairie Dog, 74.
[xxiv] John Hoogland, “Natural History of Prairie Dogs,” in Conservation of the Black-Tailed Prairie Dog, 6.
[xxv] Rodrigo Sierra-Corona et al., “Black-Tailed Prairie Dogs, Cattle, and the Conservation of North America’s Arid Grasslands,” PLoS One 10, no. 3 (2015): 6–7.
[xxvi] Hoogland, “Natural History of Prairie Dogs,” 21.
[xxvii] Natasha B. Kotliar, Brian J. Miller, Richard P. Reading, and Timothy W. Clark, “The Prairie Dog as a Keystone Species,” in Conservation of the Black-Tailed Prairie Dog, 53–54.
[xxviii] A.M. Ellison et al., “Loss of Foundation Species: Consequences for the Structure and Dynamics of Forested Ecosystems,” Frontiers in Ecology and the Environment 3, no. 9 (2005): 479.
[xxix] Kotliar, Miller, Reading, and Clark, “The Prairie Dog as a Keystone Species,” 53–64.