The Stewards of Yellowstone
Gray wolves play a much larger role in Yellowstone National Park than once believed, and epitomize trophic cascade and how ecosystems react to it
There is very little wilderness left in the world. As of 2016, only 23% of Earth’s land mass could still be classified as “wilderness,” that is, land largely unspoiled by human development. That percentage was about 10% larger in the 1990s, but recent decades have seen rapid increases in the depletion of the planet’s remaining wildlands. The United States has designated close to 110 million acres of its territory as federally-protected wilderness, which sounds like quite a bit, except those acres only account for approximately 5% of the continental U.S. area. Half of that 5% is in Alaska, meaning less than 3% of the contiguous U.S. is protected wilderness.
With all of this land being swallowed by human expansion, biodiversity becomes more precious as it shrinks with each passing year. Long ago, hunters and angry ranchers had free rein to deal with troublesome wildlife as they continued to tame more and more American wilderness. This lasted for a century and led to the near-extinction of animals like the gray wolf. In recent years, there has been a promising resurgence of their numbers in places like Yellowstone National Park. After 70 years of absence due to hunting, 41 wolves were reintroduced to the park in 1995. The significance of this decision reached further than anyone could have predicted.
When Yellowstone lost the gray wolves back in the 1920s, the park began to see alarming changes over time. Back then the concept of an interconnected ecosystem and the balance created by different species was not fully understood (or perhaps regarded at all), and so when the park lost one of its key predators, its prey began to flourish. The elk population more than doubled with no apex predator to keep it in check, numbering around 17,000 by 1995. While other carnivores like cougars and bears also preyed on elk, it made no difference with the wolves out of the picture. Elk consumed grass, shrubs, and trees like wildfire, overgrazing all of Yellowstone. Decreased hunting pressure meant that the elk didn’t need to migrate much in winter, so they consumed many young trees that usually grew during their absence. The loss of these willows and aspens hit Yellowstone’s beaver population hard, making it difficult for them to survive the cold season. Without dense grasses to hide in, mice and rabbit populations plummeted, which led to the eventual decline of foxes since they had nothing left to eat. Even bears suffered as the elk devoured all of the berries in the park, robbing them of a vital food source for storing fat used during hibernation. Bears also relied on the elk carcasses left behind by wolf packs, which were no longer available.
This dramatic loss of foliage crippled the entire Yellowstone ecosystem. Key habitats for rodents and birds disappeared, pollinating insects had fewer flowers to work with, and the lack of healthy trees contributed to soil erosion along riverbanks. The scarcity of trees also made it impossible for beavers to create dams, which negatively impacted other aquatic creatures like fish and otters. Elk congregated along rivers far longer than usual; drinking is normally a vulnerable time for herbivores, as predators will often strike while they are preoccupied with thirst. But with the wolves gone, the elk no longer had any fear and stagnated along the water for lengthy periods of time. Thousands of hooves tore up the banks, further eroding the soil and clouding the rivers.
A crystal clear picture emerged over those 7-odd decades. The withering of Yellowstone perfectly illustrated how delicate nature’s web truly is, and how removing even a single strand can create such imbalance that the entire ecosystem suffers. This chain of events is known as trophic cascade, an ecological butterfly effect that emphasizes the sensitivity of complex biotic communities, and what meddling with them can cause. Top carnivores are the limiting factor for the whole system, preserving the balance of all life within it, so eliminating the gray wolf from Yellowstone’s wilderness damaged all of the connected biodiversity. A dearth of wolves didn’t just lead to an abundance of elk, it fundamentally altered the elk’s behavior, and all other plant and animal species paid the price for it. The need to reestablish the gray wolves in the park was evident, and so biologists began reintroducing wolves in 1995 – 31 from Canada, and 10 more from Montana in 1997.
The results were a panacea for the world’s first national park. Trophic cascade works both ways, so the dire scenario created by ousting the wolves began to reverse once they reappeared. Benefits from their residency steadily trickled down to the rest of the ecosystem, and the party was over for the elk. With their unchallenged comfort gone, the herd began moving again and avoiding the wide open valleys and meadows they had previously lingered in. This gave the land a chance to recover from endless consumption. Grasses returned, and rodents and birds with them. Aspens and willows were able to mature now that the elk weren’t eating them during winter, which helped bring back the beavers. Their dams created new habitats for fish and amphibians again, as well as mudflats for new trees to sprout in. Riverbanks began to stabilize thanks to the root systems of these returned trees, curbing erosion and cleaning the water. Scavengers such as bears, eagles, ravens, and coyotes could once again feed on elk remains that the wolves discarded. Nearly all of the symptoms that slowly strangled Yellowstone began to vanish with the homecoming of the gray wolves, a phenomenon popularized in viral videos that circulated across the internet.
Despite these improvements, the wolves did not bring a magic wand to their new home. Some damage caused by 70 years of curbed vegetation continues to plague Yellowstone, particularly for trees. Long-term drought likely hindered aspen growth just as much as increased elk activity. Even with the beavers back to curate the waterways, researchers have noticed many willows failing to reach their former height. Some even stand just as short as the willows that existed prior to the reintroduction of the wolves, indicating their presence may have little to no effect, at least in the short term. “Short” indeed being the operative term, as it’s only been two decades since the wolves returned and trees can take longer to reach their limit. But this has led some to argue that the gray wolves are not the cure-all that many claim, and that other factors besides their disappearance led to the deterioration of the park. The more likely reason is that Yellowstone, while recovering, still has not fully healed and thus the effect of wolves on all of its inhabitants simply hasn’t yet manifested. The primary factor for willow growth is the height of the water table, which beaver dams nurture, and beavers could only make a comeback once the wolves had driven the elk back to their regular numbers. Time will yield the results still unseen.
But time may not favor the wolves, even in the protected boundaries of Yellowstone. Gray wolves have successfully reintegrated into the ecosystem, more than doubling their numbers and hovering around 100 or so within the park according to yearly statistics. Naturally, packs have wandered outside of the park as well, reigniting century-old fears from locals about their effect on livestock. Ranchers and residents, scientists and conservationists, all once again war with each other about wolf populations, livestock vulnerability, and the right to decide their linked fates. In 2003, the U.S. government determined that wolf populations had recovered so well in some regions that they were no longer considered endangered, but instead a potential threat once again. There was some validity to this perceived fear of wolves, as by 2007 they were suspected in the loss of nearly 3,000 animals owned by locals. Even though that number represented a relatively small percentage of overall livestock deaths, the damage had been done in the eyes of Yellowstone’s neighbors. Wolves were branded as “government sponsored terrorists” that victimized ranchers in the states that Yellowstone calls home — Montana, Idaho, and Wyoming.
Around 2008, the mob got their way and the federally-sanctioned culling of gray wolves began in Montana and Idaho. Local hunters, who had previously cried that the wolves would consume all of their hunting elk, could now set their sights on the troublesome beasts themselves. Each of the three Yellowstone states had roughly several hundred wolves living outside of the park, and it was these non-park wolves that would be targeted. But it was sometimes tricky to determine which wolves this included, as wolves regularly roamed in and out of Yellowstone, leading to even more heated debate between opposing parties. Yet Montana and Idaho only house approximately 4% of Yellowstone’s territory; the other 96% resides in Wyoming. Since the vast majority of the park and its protected wolves were in Wyoming’s jurisdiction, there was much concern about how the state government would handle the situation. After some court battles, state governments, including Wyoming, were allowed to permit wolf hunting outside of Yellowstone. Wyoming’s license to hunt them has fluctuated since going into effect, with hunting first sanctioned in 2013, then taken away again the following year until 2017. Last year, the Wyoming Game and Fish Department set a limit for 44 wolves to be legally killed; hunters claimed 76 instead.
There is a long-standing idea that government-sanctioned hunting of wolves and similar animals helps reduce illegal hunting, but a recent study indicates that this is not true. While monitoring Michigan and Wisconsin wolf populations between 1995 and 2012, during which there were six legal culling periods and six protected periods, researchers found that illegal poaching did not diminish during wolf hunting seasons. This means that wolf populations remain at risk despite promising restoration efforts and by regularly hunting hundreds of these wolves, bloodlines and breeding numbers can be stifled and made susceptible to sudden disasters such as drought, fire, or disease. Hunting may also disrupt scientific studies taking place within the park.
While their predation of rancher livestock is unfortunate, wolves don’t just impose on human happiness. Wolves also fascinate us, and in fact bring massive amounts of tourists to Yellowstone every year. In 2005, 100,000 visitors ventured to Yellowstone just to see them, contributing $30 million to the local economy. Smithsonian writer Frank Clifford deftly points out that, “revered and reviled, the wolf embodies society’s conflicting relationship with nature,” symbolizing mankind’s appreciation and disdain for the wildlife that we’ve continuously subjected to our capriciousness. Most animals cannot arouse such love and hatred from such a diverse jury, and its journey through extinction and conservation embodies the importance of preserving biodiversity in our shrinking wildernesses. Wolves are not the property of those people living around the Yellowstone region, nor hostages to their anger. Yellowstone, and the animals within reach of its influence, belong to all of us. They are America’s natural treasures, owned by and available to all, and thus should be wholeheartedly preserved.
Around 5,000 elk live in Yellowstone today, brought back to balance by their lupine compatriots. A decade is all that it took for the wolves to cut the elk numbers down by half, and as a result they returned to normal migration patterns, broke up into smaller herds, and became vigilant again. The many changes occurring in the park’s habitats are the positive effects of wolf-led trophic cascade, correcting mankind’s harm to the natural order. Yellowstone is a rare opportunity for biologists to witness what happens when an ecosystem is made whole again and the clout of a top predator is restored. Their numbers have rallied, but still court disaster if recovery measures are hampered by detrimental state laws that kill them by the thousands.
Wolves act as the stewards of Yellowstone by controlling the elk population and distributing food to other animals in the form of carrion. They paved the way for struggling animals to return and literally changed the landscape, exerting enormous influence on plant and river health. The void they left in the 20th century caused far too much damage, and should be a sharp lesson to us about the fragility of ecosystems around the world.