STANDARDS

CCSS: 4.OA.A.3, MP4, MP5, MP6

TEKS: 4.5A

The Great Gorilla Count

Scientists trek through mountains in central Africa to track a population of endangered apes

Francisco de Casa/Alamy Stock Photo

Extra-thick fur helps mountain gorillas stay warm in the mountains where they live.

JIM MCMAHON/MAPMAN ® 

Hiking through a muddy forest looking for gorilla poop isn’t easy. But for biologist Winnie Eckardt, it’s part of the job. Eckardt studies mountain gorillas at the Karisoke (kar-ee-SOH-kee) Research Center in northern Rwanda. Eckardt and other scientists recently led teams that counted the animals by looking for their dung, or poop.

Researchers camped in the forest for weeks at a time to count the gorillas. To have enough water to drink,they went during the rainy season, when “it’s miserable out there,” says Eckardt. Mountain gorillas live only in the mountains between Rwanda, Uganda, and the Democratic Republic of the Congo.

In the 1990s, scientists declared mountain gorillas critically endangered. Illegal hunting and logging had left the animals at risk of dying out. Since then, people have been working to protect mountain gorillas and their habitat. Is the population growing? “We were hoping, but you never know until [you count],” says Eckardt.

It isn’t easy to hike through a muddy forest while looking for gorilla poop. But it’s part of the job for biologist Winnie Eckardt. Eckardt studies mountain gorillas. She works at the Karisoke (kar-ee-SOH-kee) Research Center in northern Rwanda. Eckardt and other scientists recently led teams to count mountain gorillas. They counted the animals by looking for their dung, or poop.

Researchers camped in the forest for weeks at a time. They needed to have enough water to drink. So they went during the rainy season. Eckardt says that during the rainy season, “it’s miserable out there.” Mountain gorillas live only in the mountains between Rwanda, Uganda, and the Democratic Republic of the Congo.

Scientists declared mountain gorillas critically endangered in the 1990s. People hunted and logged illegally. Those practices put the animals at risk of dying out. Since then, people have been working to protect mountain gorillas and their habitat. Is the population growing? “We were hoping, but you never know until [you count],” says Eckardt.

Ape Detectives

Research center staff check on certain groups of mountain gorillas every day. The center is run by the Dian Fossey Gorilla Fund, which continues research started by Fossey in 1967. (See "Who Is Dian Fossey?" below.) The work is the longest-running study of gorillas in the world.

Some of the gorilla families are comfortable around people. But others run away as soon as they hear people nearby. So instead of trying to spot every gorilla, Eckardt’s teams look for signs that gorillas have moved through the forest. One clue: a path the big apes have cleared as they eat plants. Following these paths leads researchers to the temporary nests that gorillas sleep in each night.

Research center staff check on certain groups of mountain gorillas every day. The center is run by the Dian Fossey Gorilla Fund. The fund continues research started by Fossey in 1967. (See "Who Is Dian Fossey?" below.) The work is the longest-running study of gorillas in the world.

Some of the gorilla families are comfortable around people. But others run away when they hear people nearby. Eckardt’s teams don’t try to spot every gorilla. Instead, they look for signs of gorilla movement. The big apes eat plants in the forest. As they eat, they clear paths. Researchers follow these paths. The paths lead to temporary nests where gorillas sleep each night.

When a team finds a nest, they check it for gorilla droppings. They collect the dung to analyze later in a lab. The dung contains DNA that scientists use to identify which gorilla it came from. That way they can make sure they aren’t counting the same gorilla twice.

When a team finds a nest, they check it for gorilla droppings. They collect the dung. They analyze it in a lab. The dung contains DNA. Scientists use the DNA to identify which gorilla the dung came from. They make sure they aren’t counting the same gorilla twice.

The Dian Fossey Gorilla Fund International

Biologist Winnie Eckardt searches the forest for clues to track and count gorillas.

Survey Says . . .

Between 2015 and 2016, Eckardt’s teams spent six months surveying the gorillas’ habitat. It took another two years to analyze the dung samples they had found. Finally, the results came in: They had identified 604 mountain gorillas, the most ever counted in the area! 

“There’s strong evidence that the population is growing,” says Eckardt. That makes mountain gorillas the only great apes in the world whose numbers are actually going up. It’s also a good sign that conservation efforts are paying off. 

Eckardt’s teams spent six months surveying the gorillas’ habitat. It took another two years to analyze the dung samples they had found. Finally, the results came in. The teams had identified 604 mountain gorillas. That was the most ever counted in the area!

There’s strong evidence that the population is growing,” says Eckardt. That makes mountain gorillas the only great apes in the world whose numbers are going up. It’s also a good sign that conservation efforts are paying off. But mountain gorillas still face risks, says Eckardt. Poachers set up snares to hunt animals such as antelope. Gorillas can also be killed or injured by these traps. Every year, Eckardt’s teams find and destroy hundreds of snares.

Suzi Eszterhas/Minden Pictures

Gorillas live in family groups called troops, which usually have 5 to 10 members.

But mountain gorillas still face risks, says Eckardt. Every year, her teams find and destroy hundreds of snares that poachers set to hunt animals such as antelope. Gorillas can also be killed or injured by these traps.

A changing climate could affect the gorillas’ mountain habitat too. That’s one reason why it’s important to keep studying and counting the great apes, says Eckardt.

“It just doesn’t get boring,” she says. “We always learn something new.”

“There’s strong evidence that the population is growing,” says Eckardt. That makes mountain gorillas the only great apes in the world whose numbers are going up. It’s also a good sign that conservation efforts are paying off. But mountain gorillas still face risks, says Eckardt. Poachers set up snares to hunt animals such as antelope. Gorillas can also be killed or injured by these traps. Every year, Eckardt’s teams find and destroy hundreds of snares.

A changing climate could affect the gorillas’ mountain habitat too. That’s one reason why it’s important to keep studying and counting the great apes, says Eckardt.

“It just doesn’t get boring,” she says. “We always learn something new.”

A. In 1981, researchers counted only 242 mountain gorillas in an area called the Virunga Massif. In 1986, they counted 37 more than that. How many gorillas were there in 1986? Fill in the chart below. 

A. In 1981, researchers counted only 242 mountain gorillas in an area called the Virunga Massif. In 1986, they counted 37 more than that. How many gorillas were there in 1986? Fill in the chart below. 

B. Which equation shows how many gorillas there were in 1986? 

B. Which equation shows how many gorillas there were in 1986? 

A. 242 − 37 = ?

A. 242 − 37 = ?

B. 242 + 37 = ?

B. 242 + 37 = ?

C. 37 − ? = 242

C. 37 − ? = 242

D. 37 × ? = 242

D. 37 × ? = 242

A. By 1989, there were 309 gorillas in the Virunga Massif. That’s 50 fewer than scientists counted in 2000. How many gorillas were there in 2000? Write an equation using the variable g.

A. By 1989, there were 309 gorillas in the Virunga Massif. That’s 50 fewer than scientists counted in 2000. How many gorillas were there in 2000? Write an equation using the variable g.

B. Solve your equation from part A. What does your answer represent?

B. Solve your equation from part A. What does your answer represent?

A. In 2003, researchers counted 360 gorillas in the Virunga Massif. In 2010, they counted 464. By how much did the population grow between 2003 and 2010? Write and solve an equation using the variable p.

A. In 2003, researchers counted 360 gorillas in the Virunga Massif. In 2010, they counted 464. By how much did the population grow between 2003 and 2010? Write and solve an equation using the variable p.

B. In 2016, Eckardt’s team counted 604 gorillas. Adjust your equation from part A to find how many more gorillas there were in 2016 than in 2003.

B. In 2016, Eckardt’s team counted 604 gorillas. Adjust your equation from part A to find how many more gorillas there were in 2016 than in 2003.

 In addition to the 604 in the Virunga Massif, 400 other mountain gorillas live in a national park in Uganda. Write an equation using the variable t to find the total population.

 In addition to the 604 in the Virunga Massif, 400 other mountain gorillas live in a national park in Uganda. Write an equation using the variable t to find the total population.

Google Quiz

Click the Google Quiz button below to share an interactive version of the questions with your class. Click Download PDF for the non-interactive blank Answer Sheet.

Download PDF
Back to top
videos (2)
videos (2)
Skills Sheets (4)
Skills Sheets (4)
Skills Sheets (4)
Skills Sheets (4)
Lesson Plan (2)
Lesson Plan (2)