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Investigation 9: Ecoscenarios
Yellowstone National Park
Ecoscenario Solutions
1. Managing predators in Yellowstone National Park
In 1872, Yellowstone was created as the world’s first national park. The US Army managed the
park, building roads and enforcing poaching (unauthorized hunting) policies until the National
Park Service was created in 1916. Park policies are used
to control the number of predators in the ecosystem.
Because the park is so old, a lot of lessons have been
learned about how humans and wildlife can best share the
space. Predators like wolves and coyotes used to be
killed. People fed bears to attract them to tourist spots.
Today, national parks have strict policies that protect
wildlife. These policies help minimize the impact of the 2
million tourists that visit Yellowstone each year. For
example, killing of wolves is banned. Signs warn visitors
not to feed wildlife, especially bears.
Wikimedia Commons
Before the 1980s, it was popular for people to
feed bears. Today park policy prohibits
feeding any wildlife.
Limitations. Regulations protect animals only inside the
park. Wolves often explore far beyond the park boundaries. Several park wolves have been
hunted when they left the park boundaries. Rangers carefully monitor the park wolf packs, try to
protect them from human contact, and keep the public informed about wolves and how they
help the ecosystem.
2. Endangered Species Act and wolves
Under the Endangered Species Act of 1973, the US Fish and
Wildlife Service (USFWS) is required to create plans to protect
species in danger of extinction. In 1973, no wolf packs had been
seen in Yellowstone for 40 years. With no wolves to limit them, elk
populations increased dramatically. To help save the plants that were
being consumed by too many elk, the USFWS proposed a plan to
reintroduce wolves. Local ranchers and hunters immediately
opposed that plan. They feared wolves would eat their livestock. Elk
hunters worried the wolves would reduce the elk population.
Courtesy of National Park Service
Scientists tranquilize wolves
periodically to check their
health, put tracking collars on
them, or move them.
In 2011, wolves were removed from the endangered list. This means
the federal government handed over management of wolves to state
authorities in each of the western states where they are found. In
2012, several states sold hunting permits for wolves. The permits allow people to hunt wolves,
but limit the number of wolves that can be hunted. In 2013, 550 wolves were killed outside the
park boundaries in the states surrounding Yellowstone.
Today, about 98 wolves live within the park. When they aren’t being hunted, wolf populations
can grow fast, due to the abundant food supply.
Limitations. The Endangered Species Act often focuses protection on one species, instead of
looking at the entire ecosystem. Many local people did not like the wolf management plan
because it came from the federal government instead of local government. There is now pressure
FOSS Populations and Ecosystems Course, Second Edition
© The Regents of the University of California
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Investigation 9: Ecoscenarios
Yellowstone National Park
to remove all protection of wolves. There are anti-wolf groups who try to influence state
management plans. Neighboring ranchers continue to object to wolf protection plans.
3. Environmental groups
Environmental groups can help support the Yellowstone ecosystem. Defenders of Wildlife was
founded in 1947. This national organization focuses on wildlife and habitat conservation
(protection) and the protection of biodiversity. The group works with ranchers to design safer
ways for livestock and wolves to live together. They help construct electric fencing and use dogs
or people to guard livestock. When wolves kill livestock, Defenders of Wildlife reimburses the
rancher for up to $3,000 per animal. Between 1995 and 2015, Defenders of Wildlife has made
over 900 payments, totaling more than $1.4 million.
The Western Wolf Coalition works with scientists, hunters, ranchers, and Indian Tribal leaders
from more than 20 different groups. The coalition is working to make sure new state wolf
management plans are designed using scientific knowledge of wolves. This group tries to educate
people who live in states with wolves, and to correct misinformation that people may have heard
about wolves.
Limitations. Now that wolves have been removed from the endangered species list, the law
offers fewer protections. Public meetings have focused on a plan for people and wolves to coexist.
Emotions run high at public meetings, and many people feel strongly that the wolf populations
should be decreased. It is a challenge for Defenders of Wildlife and the Western Wolf Coalition to
keep the public informed with scientific information about wolves.
Current Status
Yellowstone is a good example of how a keystone species can affect an entire ecosystem.
Ecologists have studied the plants and animals of Yellowstone for nearly a century, so there is an
excellent record of what the park looked like without wolves for 70 years. Ecologists can follow
the changes since wolves returned over 15 years ago.
Courtesy of National Park Service
A wolf pack closes in on a bull elk. Taking down an adult male elk
is dangerous for wolves. One kick from the elk could mean death.
FOSS Populations and Ecosystems Course, Second Edition
© The Regents of the University of California
Courtesy of National Park Service
Each shape represents a wolf pack within
Yellowstone National Park in 2011.
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Investigation 9: Ecoscenarios
Yellowstone National Park
As expected, the wolves eat mostly elk. Scientists estimate that wolves kill an average of 22 elk per
wolf each year. But the wolf’s impact on the ecosystem has gone beyond reducing the elk
population. When wolves are around, the elk behave differently. In a wolf-free ecosystem, elk
remained in one spot and ate many of the plants before moving on. With the wolves back, the elk
herds move around more often. This means they do not destroy populations of willows and
aspens. With more willow and aspen trees, songbirds have more habitat, and their populations
have increased.
With more willow and aspen trees, beaver populations
also increased. Beavers are considered another kind of
keystone species. Scientists call beavers ecosystem
engineers. Beavers design and build dams in rivers and
streams. The larger beaver populations built many more
dams throughout the park. These dams help create
meadows where many kinds of plants can grow.
Beaver dams also filter the streams, improving water
quality for fish. This creates more food for fish-eating
predators like hawks, bald eagles, and grizzly bears. By
restoring the keystone population of wolves, there has
been a chain reaction of improvements in the
ecosystem.
FOSS Populations and Ecosystems Course, Second Edition
© The Regents of the University of California
Courtesy of National Park Service
An increase of beaver activity has dramatically
improved the Yellowstone ecosystem.
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