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Monkey Crossing: How building a bridge could help save golden lion tamarins in Brazil.

A tiny monkey jumps from tree to tree in a rainforest in Brazil. It's chasing a tasty bug to eat. Suddenly, the trees dead-end at a highway. The bug escapes, and the monkey has nowhere to go.

This adorable primate is a golden lion tamarin. It lives in the Atlantic Forest along Brazil's eastern coast (see Disappearing Forest, page 6). That area has been ravaged by deforestation. Over centuries, people have cut down most of the forest to make space for cities and farmland. What's left are isolated pockets of trees.

Living in these fragmented areas puts the tamarins in danger. If the animals can't move around to find food and mates, they can't survive.

Luckily, scientists are working on a solution. They're helping to build a bridge over a major highway dividing the forest. Tamarins will be able to use the bridge to travel between two sections of forest on either side. That should give tamarins the room they need to thrive.

"It's about keeping nature connected," says ecologist Clinton Jenkins. He's the vice president of SavingSpecies, a conservation group involved in the project. "Nobody likes to be trapped in a little space."

Losing Ground

Golden lion tamarins were once common in parts of the Atlantic Forest. But for decades, people hunted them for food and because they thought the animals carried diseases. By the 1970s, fewer than 200 of the tamarins remained in the wild. So scientists began breeding them in zoos and releasing them into their natural habitat.

Today, about 2,000 golden lion tamarins live in Brazil. But they're still endangered. Part of the problem is that a major highway called BR-101 cuts right through parts of the forest where the animals live. "It's impossible for the tamarins to cross the highway," says Erin Willigan, the executive director of SavingSpecies. "They're imprisoned on either side."

Bridge Builders

Scientists are teaming up to help the tamarins. They designed a bridge that will connect two sections of the tamarins' habitat. The bridge will be covered with soil, grass, and trees to make it look like the natural forest (see A Bridge for Tamarins, page 5).

In the past few months, the scientists have been planting trees on each side of BR-101. When those trees mature, they will bring the edges of the forest right up to the sides of the bridge. Tamarins will be able to use the bridge to safely travel between two forested areas. "We're going to bring families of tamarins closer to each other," says Stuart Pimm, the president of SavingSpecies.

Connecting different tamarin populations will be good for the whole species. When animals mate, they pass along genes to their offspring. Populations of animals that have a diverse mix of genes are better able to fight off diseases.

The bridge in Brazil is mainly for the tamarins. But scientists expect other animals, such as wildcats, to use it too. Different species in an ecosystem depend on each other to survive. So protecting individual animals should help preserve the biodiversity of the whole Atlantic Forest.

Room to Roam

Paths that connect animal habitat, called wildlife corridors, have been built all over the world (see Making Connections, below). Some are bridges that traverse highways. Others are tunnels under roads. These paths help animals move around while avoiding cars.

Scientists hope that wildlife corridors will also help animals cope with climate change. As temperatures rise, animals will need to move to cooler places to survive. "If you're imprisoned in an area, it's going to be really hard to move," Pimm says.

Workers began constructing the bridge for the tamarins in November 2018. It's just the first corridor that SavingSpecies wants built in the Atlantic Forest. The group hopes to connect other patches of trees where animals live. "With a large enough forest, golden lion tamarins have a good chance at survival," Willigan says.

A Bridge for Tamarins

The overpass will connect two forest areas where golden lion tamarins live. Here's how the finished bridge will look.

Scientists planted trees to bring the forest's edge to the foot of the bridge.

A major highway cuts through the Atlantic Forest.

Grass and trees on the bridge will make it appealing to the tamarins.

Think: Why might planting grass and trees on the bridge make it more likely that tamarins and other wildlife will use it?

words to know

primate--an animal belonging to an order that includes monkeys, apes, and humans

habitat--the place in nature where an animal or a plant usually lives

gene--a group of molecules that pass on traits from parent to offspring

ecosystem--all the living and nonliving things that interact with one another in a place

biodiversity--the variety of living things in an environment

Disappearing Forest

About 85 percent of Brazil's Atlantic Forest has been cut down. What remains are disconnected sections of trees.

Think: How might scientist have chosen the bridge's site?

Making Connections

All over the world, bridges and tunnels help animals cope with fragmented habitats.

Crabs on Christmas Island, in the Indian Ocean, use this bridge to scurry safely to the sea.

A tunnel under a highway connects two elephant populations in Kenya.

Think: How are these wildlife corridors different from the bridge being built for the tamarins?

Monkey Crossing


READING LEVELS: Lexite 880 / Guided Reading Level T

NEED A LOWER READING LEVEL? To access this article at a lower reading level, go to


Analyze data to explain how humans have changed the habitat of golden lion tamarins over time.



Core Idea: LS4.D: Biodiversity and humans

Practice: Analyzing and interpreting data

Crosscutting Concept: Stability and change


Reading Informational Text: 5.

Describe the problems and solutions in a text.


Science: 3.2D, 3.9A, 4.2D, 5.2D, 5.9C, 6.2E

ELA: 3.9D, 4.9D, 5.9D, 6.8D

Lesson Plan

(1) Use a photo to prompt a discussion about golden Uon tamarins' habitat.

Open the digital edition of the magazine to show the presentation view of pages 6-7. Use the spotlight tool to highlight the image of the zookeeper releasing a tamarin into the wild on page 7. Have students make observations about the image. Ask:

* What do living things need to survive? (food, water, shelter, and space)

* How would you describe the habitat shown in the picture?

* What problems might the monkey in the picture face if a road were built in its habitat?

(2) Read the article and review it with a skills sheet.

Read "Monkey Crossing" as a class. Switch readers after each paragraph. After reading the article allow students to independently complete the skills sheet "Problem Solvers," available at Ask: How is the BR-101 highway affecting tamarins

(3) Analyze data from a bar graph.

Partner students to complete the skills sheet "Paradise Lost" (T3). Then ask students to brainstorm reasons why less of Brazil's Atlantic Forest has been cleared in recent years. Remind students to use evidence from the graph and the article in their answers.

(4) Compare data from the graph and a map to understand how tamarins' habitat has changed.

Have students work with their partners to compare the data in their bar graph with the data shown in the map "Disappearing Forest" on page 6. Ask:

* What patterns do you notice in the data from each source?

* What predictions can you make about the survival of golden lion tamarins in the future based on these patterns?

TEACHING TOOLS available at

Skills sheets:

Paradise Lost (T3): Analyze a graph showing deforestation in five-year time periods in Brazil's Atlantic Forest.

No-Sweat Bubble Test (TIO): Answer multiple-choice questions about the article.

Problem Solvers (online only): Identify problems and solutions in the article.

Wildlife Corridors (online only): Learn how people are building pathways to help animals safely cross roads in their habitats.

Habitat Hopper (online only): Navigate your animal to a safe area of forest as the forest gets smaller and smaller.

Caption: Tiny Creature Tamarins are among the smallest primates. Adults weigh less than 2 pounds!

Caption: Golden lion tamarins are social--even with people. That makes them popular in zoos.

Caption: Small isolated patches of forest can trap animals that need to move freely.

Caption: A zookeeper releases a golden lion tamarin into the wild.


Paradise Lost

In "Monkey Crossing" (pp. 4-7), you read about how Brazil's Atlantic Forest, the home of golden lion tamarins, has been destroyed by deforestation. The graph below shows the area of forest cut down every five years from 1985 to 2014. Study the graph, then answer the questions.


1. During which time period shown on the graph was the largest area cleared in Brazil's Atlantic Forest? --

2. About how many square kilometers of forest were lost because of deforestation from 1990 to 1994? --

3. About how much more forest was cut down from 1995 to 1999 than from 2010 to 2014?

(A) 3,000 [km.sup.2]

(B) 3,500 [km.sup.2]

(C) 4,000 [km.sup.2]

(D) 4,500 [km.sup.2]

4. Part A. What can you conclude based on the data in the graph?

(A) More of Brazil's Atlantic Forest has been cleared in recent years.

(B) Less of Brazil's Atlantic Forest has been cleared in recent years.

(C) Brazil's Atlantic Forest is larger today than it was in 2000.

(D) Brazil's Atlantic Forest is smaller today than it was in 2014.

5. Part B. How does the graph's data support the answer to question 4? Write your answer on the back of this paper. --

* Paradise Lost (Reproducible, T3)

1. 1985 to 1989 2.5,000 [km.sup.2] 3. b 4. b 5. The graph shows that the amount of area cleared in each five-year period has decreased over time.


No-Sweat Bubble Test

Directions: Read each question below, then use the article "Monkey Crossing" (pp. 4-7) to determine the best answer.

1. In which type of habitat do golden lion tamarins live?

(A) desert

(B) forest

(C) grassland

(D) wetland

2. According to paragraph 2 of the article, the Atlantic Forest has been cut down to make space for cities and farmland. How has that change affected tamarins?

(A) Tamarins have become more social animals.

(B) Tamarin population numbers are increasing.

(C) The tamarins aren't able to move around and find mates and food.

(D) Zoos can release more tamarins into the wild.

3. What problems have tamarins faced in recent decades?

(A) People have hunted them for food.

(B) Their habitat has been cut down.

(C) People have killed them because they thought the monkeys spread diseases.

(D) all of the above

4. What solution are scientists working on to help tamarins cross a highway in Brazil?

(A) They're driving tamarins across the road.

(B) They're breeding tamarins in zoos and releasing them on the other side of the road.

(C) They designed a wildlife bridge over the road.

(D) all of the above

5. What can you conclude from the map

"Disappearing Forest" on page 6?

(A) The forest is much smaller today than it was in the past.

(B) The forest is much larger today than it was in the past.

(C) The road is still being built.

(D) Brazil is the smallest country in South America.

6. The author states, "Some [wildlife corridors] are bridges that traverse highways." Which of the following is the best definition for traverse?

(A) to avoid

(B) to block

(C) to climb

(D) to travel across

7. How will wildlife corridors help animals cope with a warming climate?

(A) by allowing animals to move to cooler places

(B) by containing animals in safe areas

(C) by slowing down climate change

(D) by protecting animals from being hunted

8. What is the purpose of the sidebar "Making Connections," on page 7?

(A) to show an example of the bridge for tamarins

(B) to give examples of corridors for other animals

(C) to explain where tamarins live

(D) to show the steps for building a corridor

9. Which sentence from the article best supports the claim that the bridge might give tamarins a chance of survival?

(A) "Golden lion tamarins were once common in parts of the Atlantic Forest."

(B) "Today, about 2,000 golden lion tamarins live in Brazil."

(C) "Connecting different tamarin populations will be good for the whole species."

(D) "But scientists expect other animals, such as wildcats, to use [the bridge] too."

10. Which statement is most important to include in a summary of the article?

(A) Brazil's Atlantic Forest is in South America.

(B) Bridges can help animals cope with fragmented habitats.

(C) Golden lion tamarins are primates.

(D) Scientists are planting trees in Brazil.

* No-Sweat Bubble Test (Reproducible, T10)

1. b 2. c 3. d 4. c 5. a 6. d 7. a 8. b 9. c 10. b
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Title Annotation:life science
Author:Potenza, Alessandra
Geographic Code:3BRAZ
Date:Feb 1, 2019
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