STANDARDS

CCSS: 3.OA.D.8, 4.OA.A.2, 4.OA.A.3, 5.OA.A.1, MP5, MP6, MP7

TEKS: 3.5A, 4.5A, 4.4D, 5.4E


Bison’s Big Return

After centuries of struggle, bison numbers are on the rise in the American West

RONAN DONOVAN/National Geographic Creative

Curious how a bison is feeling? Check out its tail! If it hangs down, the bison is calm. But a tail that's sticking up means that the animal could be ready to charge!

What animal is our national mammal, holds a special place in American history, and has come back from the brink of  extinction ? It’s the bison! Throughout western North America, bison numbers have climbed from about 1,000 in 1900 to 400,000 today.

This turnaround didn’t happen overnight. It took many people and many years of work to save North America’s largest land mammal from extinction.

Before 1800, more than 40 million bison roamed the continent. By 1900, government-sponsored hunting programs and settlers moving westward had nearly wiped out the species. Fewer than 1,000 bison were left. 

Since then, conservationists, Native American tribes, and federal programs have helped to bring bison back. In May 2016, President Barack Obama signed a bill naming the bison America’s first national mammal. Joining the bald eagle, bison now stand as a symbol of our country and of successful conservation efforts.

What is our national mammal? It’s the bison! And it has come back from the edge of extinction. Bison numbers have climbed in Western North America from about 1,000 in 1900 to 400,000 today. 

This didn’t happen overnight. It took many people and many years of work to save them from extinction.

More than 40 million bison roamed the continent before 1800. Hunting and settlers moving west had nearly wiped out the species by 1900. Fewer than 1,000 bison were left.

Conservationists, Native American tribes, and federal programs have helped to bring bison back. President Barack Obama named the bison America’s first national mammal in May 2016. Bison now stand as a symbol of our country and successful conservation efforts.

Wild Counting

Bison are the largest mammals in North America. Males can stand 6 feet tall at the shoulder and weigh up to a ton. But for biologist Rick Wallen, bison usually appear as tiny brown dots. That’s because he counts them from an airplane! 

Wallen works at Yellowstone National Park, the center of wild bison’s comeback. The park spans 2.2 million acres in three states. It’s home to 4,900 bison—the nation’s largest wild population. 

To manage this population, Wallen counts the bison every spring. He and a few co-workers fly through the park in two small planes. Moving at speeds up to 90 miles per hour, they count as many animals as they can in one day. “After you’ve done it for a while you get better at counting by fives or tens,” Wallen says.

The planes fly between 500 and 1,000 feet above the herd. It’s often a rough flight. “It’s like an amusement park ride,” says Wallen. “If you don’t have the stomach for it, you won’t like it.” 

The gut-churning work has paid off. Using Wallen’s data, park officials can keep better track of the animals. This helps them know how many bison the park can safely support.

Bison are the largest mammals in North America. Males can stand 6 feet tall at the shoulder. And they weigh up to a ton. But biologist Rick Wallen usually sees bison as tiny brown dots. That’s because he counts them from an airplane!

Wallen works at Yellowstone National Park, which is the center of wild bison’s comeback. The park spans 2.2 million acres in three states. It’s home to 4,900 bison which is the nation’s largest wild population.

Wallen counts the bison every spring to manage the population. He and a few co-workers fly through the park in two small planes. The planes move at up to 90 miles per hour. Wallen and his co-workers count as many animals as they can in one day. “After you’ve done it for a while you get better at counting by fives or tens,” Wallen says.

The planes fly between 500 and 1,000 feet above the herd. It’s often a rough flight. “It’s like an amusement park ride,” says Wallen. “If you don’t have the stomach for it, you won’t like it.”

The gut-churning work has paid off. Park officials can keep better track of the animals using Wallen’s data. This helps them know how many bison the park can safely support.    

Appreciating Bison

Bison have had another important ally in their comeback: Native Americans. For more than 10,000 years, bison have served as the cultural and spiritual lifeblood of many Native American tribes.

“Our ancestors used every part of the buffalo for food, shelter, and clothing,” says Dianne Amiotte-Seidel. She’s a member of the Oglala Lakota Sioux Tribe at the Pine Ridge Indian Reservation in South Dakota. (Buffalo is another term for bison.)

Amiotte-Seidel works at the Intertribal Buffalo Council, an organization of 62 tribes dedicated to bringing bison back. In 1991, the council began breeding bison and raising them on protected land. They started with just a few hundred. Native Americans now have 15,000 buffalo across the country.

The council also supports efforts for teaching students the importance bison have played in Native American history. Some schools, like the Red Cloud Indian School in Pine Ridge, invite Lakota students to witness a ceremonial buffalo kill. 

Throughout the Lakota’s history, these sacred events provided food and clothing for the community. “Without the buffalo, there would be no Lakota,” says Roger White Eyes, a teacher at Red Cloud. 

And without the Lakota and other tribes, there might have been no buffalo comeback.

Bison have had another important ally in their comeback: Native Americans. They have been important to many Native American tribes for over 10,000 years.

“Our ancestors used every part of the buffalo for food, shelter, and clothing,” says Dianne Amiotte-Seidel. She’s a member of the Oglala Lakota Sioux Tribe at the Pine Ridge Indian Reservation in South Dakota. (Buffalo is another term for bison.)

Amiotte-Seidel works at an organization of 62 tribes dedicated to bringing bison back. It is called the Intertribal Buffalo Council. The council began breeding bison and raising them on protected land in 1991. They started with just a few hundred. Native Americans now have 15,000 buffalo across the country.

The council also supports efforts for teaching students the importance of bison in Native American history. Some schools invite Lakota students to witness a ceremonial buffalo kill.

These sacred events provided food and clothing for the community throughout the Lakota’s history. “Without the buffalo, there would be no Lakota,” says Roger White Eyes, a teacher at Red Cloud Indian School in Pine Ridge.

And without the Lakota and other tribes, there might have been no buffalo comeback. 

Sean Crane/Minden Pictures

Yellowstone National Park is the only place in the U.S. where bison have lived continuously since prehistoric times. 

In 1901, there were only 24 bison in Yellowstone National Park. Through a restoration program, the U.S. Army brought bison from Montana and Texas to the park. By 1911, there were 192 bison. You want to find the difference between the bison population in 1901 and 1911.

In 1901, there were only 24 bison in Yellowstone National Park. Through a restoration program, the U.S. Army brought bison from Montana and Texas to the park. By 1911, there were 192 bison. You want to find the difference between the bison population in 1901 and 1911.

What values do you know? 

What values do you know? 

What is the unknown value you are trying to find? 

What is the unknown value you are trying to find? 

The tape diagram to the right represents an equation to calculate the unknown value, represented by the letter z. Write a number sentence describing this diagram.

The tape diagram to the right represents an equation to calculate the unknown value, represented by the letter z. Write a number sentence describing this diagram.

Solve for z. What does z represent?

Solve for z. What does z represent?

There are two major bison herds at Yellowstone, the central herd and the northern herd. In 1970, when park staff began counting the herds, the northern herd had 217 bison and the central herd had 261.

There are two major bison herds at Yellowstone, the central herd and the northern herd. In 1970, when park staff began counting the herds, the northern herd had 217 bison and the central herd had 261.

You want to find the total population of the two herds in 1970. What operation should you use?

You want to find the total population of the two herds in 1970. What operation should you use?

What is the unknown value?

What is the unknown value?

Fill in the tape diagram to the right to calculate the total bison population. Use the variable r to represent the unknown value.

Fill in the tape diagram to the right to calculate the total bison population. Use the variable r to represent the unknown value.

Write a number sentence that represents your tape diagram.

Write a number sentence that represents your tape diagram.

Solve for r. What does r represent?

Solve for r. What does r represent?

You want to calculate how much the central herd grew between 1975 and 1995. Draw a tape diagram to show the difference in the central herd’s size between 1975 and 1995.

You want to calculate how much the central herd grew between 1975 and 1995. Draw a tape diagram to show the difference in the central herd’s size between 1975 and 1995.

Write an addition equation using the variable q to show how the central herd grew between 1975 and 1995.

Write an addition equation using the variable q to show how the central herd grew between 1975 and 1995.

Solve for q. What number does q represent?

Solve for q. What number does q represent?

Scientists can use estimates to get a general understanding of how data changes over time.

Scientists can use estimates to get a general understanding of how data changes over time.

Let’s say scientists wanted to estimate how many times bigger the northern herd grew from 1995 to 2015. First, round the herd counts for 1995 and 2015 to the nearest hundred. 

Let’s say scientists wanted to estimate how many times bigger the northern herd grew from 1995 to 2015. First, round the herd counts for 1995 and 2015 to the nearest hundred. 

Write a multiplication equation using the variable t to estimate how many times bigger the herd grew in that time frame.

Write a multiplication equation using the variable t to estimate how many times bigger the herd grew in that time frame.

Solve for t.

Solve for t.

The size of each herd at Yellowstone can change depending on many factors. What do you notice about the northern and central herd populations in 2005 compared with 2015? 

The size of each herd at Yellowstone can change depending on many factors. What do you notice about the northern and central herd populations in 2005 compared with 2015? 

Say you want to use k to represent the decrease in total bison population in Yellowstone between 2005 and 2015. Write an equation using parentheses to set up this problem.

Say you want to use k to represent the decrease in total bison population in Yellowstone between 2005 and 2015. Write an equation using parentheses to set up this problem.

Solve for k.

Solve for k.

In 1929, the bison population at Yellowstone was 1,124. For the next four years, park officials did not count bison. This was the beginning of the Great Depression, a time when jobs and money were scarce. 

In 1929, the bison population at Yellowstone was 1,124. For the next four years, park officials did not count bison. This was the beginning of the Great Depression, a time when jobs and money were scarce. 

In 1935, officials began counting bison again. Say the variable d represents the change in Yellowstone’s bison population between 1929 and 1935. If there were 847 bison in 1935, what is the value of d? 

In 1935, officials began counting bison again. Say the variable d represents the change in Yellowstone’s bison population between 1929 and 1935. If there were 847 bison in 1935, what is the value of d? 

How do you think the circumstances of the Great Depression might have affected care of the bison at Yellowstone at that time? 

How do you think the circumstances of the Great Depression might have affected care of the bison at Yellowstone at that time? 

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