Yellowstone National Park is 150 years old. Scientists have identified significant changes in the park over the course of that century and a half. The five most important.
Yellowstone National Park in the United States celebrates its fiftieth anniversary this yeare birthday. On March 1, 1872, President Ulysses S. Grant Yellowstone National Protection Act, which led to the creation of the world’s first national park according to Guinness World Records. In the 150 years since its establishment, Yellowstone has not only developed into a unique scenic area and beloved tourist attraction, but is also a valuable research area for scientists. In that century and a half, researchers have been able to identify important changes. Smithsonian Magazine explained what makes Yellowstone today different from the same region 150 years ago.
1. The most obvious change is undoubtedly the disappearance and return of the wolf. Thousands of years before Yellowstone became a national park, wolves roamed here. You would have expected that the declaration of Yellowstone National Park in 1872 would benefit the wolves that were already exterminated at the time. But nothing is less true. While all kinds of animals are now protected, wolves went unprotected because they killed more popular animals like deer and bison. The animals were actively hunted in Yellowstone and in the early 1920se Century were widely poisoned. Between 1924 and 1926, the last of the wolves were killed in Yellowstone.
A lone wolf was seen sporadically in the following years, but no packs of wolves existed for decades. This immediately had a disastrous effect on the landscape. The absence of wolves caused an explosion in the number of wapitis and coyotes which upset the balance of the entire ecosystem: willows and poplars were eaten immediately and were not given a chance to grow. Fewer trees means fewer songbirds. In addition, river banks were eroded because there were fewer trees to anchor, which in turn had consequences for beavers who could no longer build dams. These are just a few examples of negative consequences.
Several scientific studies have shown that the degradation of the Yellowstone ecosystem is linked to the wolf’s disappearance. It would take years, but 14 wolves were brought to Yellowstone from Jasper National Park in Canada in 1995, and another 17 the following year. Since then, this early group has grown to over a hundred wolves within the protected boundaries of the park. About 500 wolves now live in the greater Yellowstone area (ten times the size of the national park itself). Scientists have followed the impact of wolves on the ecosystem from the beginning and are constantly making new discoveries to this day.
Wolves confirmed, among other things, that the Wapitis herd is stable today. There were far too many of these large deer to live for it and large numbers had to be shot every year. Now the park has about 6000 wapiti and the number does not fluctuate from year to year: there is no massive growth in the good years and massive death in the years with little food. The decline in the number of wapiti gave the trees a chance to grow again, it was easier for beavers to build dams again and the number of fish increased because they thrive better in shaded, cool water. Wolves are said to be partly responsible for changing the course of the rivers in the park.
2. The boundaries of Yellowstone National Park have changed with difficulty, but the natural areas surrounding the park have not changed either: the greater Yellowstone area. This area was originally ten times the size of the national park itself, but is rapidly decreasing in size.
The Montana State University study “Trends in Vital Signs of the Greater Yellowstone Application of the Wildlife Index” shows that the area’s population has tripled since 1970. This number is expected to double by 2050. Additionally, tourism has grown exponentially. Large groups of “country” hikers in particular bother and drive the animals out of the places where they usually feed, sleep and eat. Today, Yellowstone National Park is surrounded by homes on all sides. This ensures that the link between different ecosystems is broken, and for example, wolverines can no longer move from one alpine forest to another.
Another problem is the invasive plants and weeds that are spread out of the park by horses and other livestock and are increasingly invading the national park. These types of plants replace native plants that are more nutritious for wildlife. In recent years, collisions between wild animals and humans have become more frequent. To give an example: ungulates stay within the park boundaries in the summer, but often go beyond the boundaries in the winter to search for food. Now that the area around Yellowstone is less natural and more densely populated, this is causing more problems.
3. On the plus side, bison thrive in Yellowstone. Yellowstone is the only place in the United States where bison have lived continuously since prehistoric times. Nowadays, the Yellowstone flock is the largest group that roams freely on public lands in the United States. Animals exhibit natural behaviors such as migration, season of wounds, and fighting with competitors. Less than a century ago, the bison disappeared from Yellowstone.
The story is well known: in the past, the prairies of the United States were almost black with bison. Native American tribes hunted the animals on foot and without firearms, killing no more than they needed to. That changed drastically when, around 1800, white European Americans began exploring the west of the country and inflicted mass bull slaughter. Even after Yellowstone was declared a national park in 1872, the animals were not safe there. At one time, there were only twenty people left and the park rangers decided to participate to increase the number of bison. They brought about twenty domesticated bulls from a farm to Yellowstone with the intent of mixing the two groups together. And that’s exactly what happened. They had offspring together and by 1950 there were already 1,300 bison in the park. In 1990 there were even 3000.
The downside to this is that in the winter, when there is less food, the bison move outside the park boundaries and there come into conflict with farmers. Bison eat the same as farmers’ cattle, and can sometimes be dangerous to humans, and can transmit gallbladder disease (a disease that causes miscarriages and stillbirths) to cattle. Therefore, it remains necessary every year to shoot some bulls or move them to other areas.
4. The heaters change in size and become larger or smaller. Yellowstone owes its unique landscape of more than 10,000 geothermal phenomena (more than the rest of the world combined) to the massive underground volcano. This volcanic system is constantly changing. Even the world-famous Old Faithful volcano is less reliable than its name suggests. In the 1870s, a heater would blow water into the air every 60 to 70 minutes. Since the 1950s, the intervals have been getting longer and longer, coming to about 94 minutes now.
An even greater change can be seen in the Steamboat Geyser, the world’s tallest active spring at around 120 metres. This heater was always unpredictable and often silent for years – sometimes even fifty. Since 2018, this Steamboat has suddenly become more active and has an eruption almost every week. Perhaps this change relates to shifts in subterranean magma that force hot gases to find their way out.
Scientists also suspect that drought affects the height of geysers. In the future, if the climate becomes warmer and drier, there will likely not be enough water for the spectacular eruptions we can see today.
5. Yellowstone is getting warmer and drier. Like the rest of the world, Yellowstone cannot escape global warming. Climate assessment research in Greater Yellowstone shows that winters are becoming milder, summers warmer, and growing seasons becoming about a month longer. Compared to 1950, the average temperature in Yellowstone is currently 1.3°C.
Higher temperatures also mean that precipitation falls more often as rain and less as snow. Since 1950, snowfall has decreased by an average of 60 cm per year. Spring begins a few weeks earlier, so the moment when most of the meltwater flows through the rivers also falls earlier in the year. This increases the risk of wildfires later in the year.
Climate change is also having dire consequences for Yellowstone’s wildlife. When the snow melts faster than in the past, floods occur more frequently and the nests of birds such as Arctic divers, white pelicans, cormorants and trumpeter pelicans are washed away. Another consequence associated with rivers is that the water becomes too warm for fish such as trout. They then focus on smaller areas where the water is still cold and this ensures that diseases can spread easily among the fish. This actually happened in 2016.
According to the New York Times, the consequences will only become more serious in the future. Although ecosystems are constantly changing, climate change is happening at such a rapid pace that plants and animals cannot adapt quickly enough. Drought is increasing wildfires in Yellowstone and preventing those forests from recovering. As a result, forests disappear and more grasslands are created.
Invasive plant species will also occupy more and more land, in part because – after a fire – they emerge faster than native species and thus displace them. Invasive plants contain fewer nutrients and are more susceptible to fire. A good example of such an invasive herbaceous species is fescue dravik. This grows early in the spring and draws all moisture from the soil. It also disappears quickly, making it difficult for animals like wapitis and bison to find food later in the year next summer. So the animals will leave the park in the summer in search of food, and as a result, collisions between animals and humans will occur much more often than is really the case.