Would you believe someone if they told you that the best thing to happen to the elks of Yellowstone is a pack of hungry wolves? Ever since wolves were reintroduced to park by rangers in 1995, the health and population of the elks there has greatly improved.
In January of 1995, a truck carrying eight grey wolves drove into Yellowstone, on its way to figure out what exactly made for a healthy ecosystem. After being overly hunted by westerners in the late 1800s, the wolf population of Yellowstone was gone by 1920. When this happened, the people of the area grew confident that the elk population would now flourish. And for a while, their expectations were met as the elk population exploded.
However, without the wolves to hunt them and keep them in check, the elk grew in number to such a point that their food sources were diminished. Having stripped away all of the bark and leaves of willow and aspen trees, the elk became reliant on alternate foods, such as shrubs. This in turn caused a decline in young trees growing to full size, causing the local beaver population to suffer. Thus, the lack of beaver dams changed the way the rivers flowed. The lack of carrion (previously left behind by wolves) meant that local scavengers, such as eagles and coyotes, grew hungry. All of these factors made for an unhealthy ecosystem.
The reintroduction of just eight wolves to Yellowstone in 1995 has provided biologists with a unique perspective into the restoration of an ecosystem. Scott Creel, a professor of ecology at Montana State University, has been busy studying the relationship between elk and wolf populations in the Gallatin Canyon, and more specifically what exactly elk do in the presence or absence of wolves.
“Elk have proven to be pretty adaptable,” says Creel. “When wolves are around, they’re more vigilant and do less foraging.”
When wolves are around, elk move into heavy timber and gather in smaller herd units to avoid detection. But when wolves are absent, elk tend to hang around in grassy, open fields, and in larger herd units. Today, the park’s 100 wolves, divided into 10 different packs, have driven the elk away from young trees, allowing the ecosystem to be restored to equilibrium.
Researchers have determined that a larger population of wolves is overall better for scavengers of all kinds, from eagles to grizzly bears. More hunting by wolves equals more dead animals, which equals more food for the scavengers. While once depending on the frigid winters to provide elk carcasses, scavengers can now rely on the more dependable option of elk carcasses provided by a pack of wolves.