The idea in the given quotation is that freedom and independence are essential to the lives of the Indian people. This is why the quetzal is the national symbol of the Indian people in Guatemala.

The protagonist of The Bean Trees is Taylor Greer, who leaves her family home in Kentucky and heads west to find adventure, freedom and independence. In relation to the quotation, Taylor begins the novel as the macaw bird and then becomes a quetzal. In other words, she begins the novel in a small town in Kentucky, metaphorically caged (like the macaw birds at the zoo) by the limited prospects there, and she becomes free and independent like the quetzal bird. Taylor leaves her hometown because she is afraid that her spirit, and her independence, will die if she stays. She fears dying in her own cage, just like the quetzal.

The idea in the quotation that the quetzal will die if it is kept in a cage also relates to the characters Estevan and Esperanza, who are political refugees from Guatemala. Estevan and Esperanza flee to America in search of freedom. The idea that one might metaphorically die if one's freedom is taken away helps explain Estevan and Esperanza's decision to leave their daughter, Ismene, behind in Guatemala. The obvious reason why they do this is because they do not want to give to the authorities the names of other members of the teachers' union, knowing that if they did, those members would lose their freedom and perhaps even die. Estevan and Esperanza make enormous sacrifices to protect the freedom of their friends, knowing how essential freedom is to life.

Nonetheless, when Estevan and Esperanza essentially sacrifice their daughter for the freedom of their friends, it still seems like a difficult decision to fully understand. It is easier to understand, however, if we appreciate that Estevan and Esperanza's own freedom is synonymous with and essential to their lives. They left their daughter behind in part because if they had stayed, they too would have died in cages, metaphorical and literal.

When Estevan and Esperanza move to America, they still lack freedom, because they are undocumented immigrants, meaning that they are denied the rights and freedoms afforded to American citizens. They only become free in any meaningful sense when they travel to a Cherokee reservation, where they are much less likely to be apprehended by the authorities. They, like Taylor, make sacrifices and endure hardships to acquire their freedom. And they, like the quetzal, need freedom to live.

What is the symbolism in the following quote from The Bean Trees?

He told me that the national symbol of the Indian people in Guatemala was the quetzal, a beautiful green bird with a long, long tail. I told him I had seen military macaws at the zoo, and wondered if the quetzal was anything like those. He said no. If you tried to keep this bird in a cage, it died.

One of the main themes in Barbara Kingsolver’s The Bean Trees is freedom. Kingsolver tells the story of Taylor Greer, born Marietta Greer, who has left her hometown in search of freedom from the typical life she sees all around her. Girls in her hometown didn’t generally have adventures; they got pregnant and dropped out of high school, tied to a life of poverty and motherhood. Taylor is determined not to forge the same path. She graduates high school, works and saves money, and then leaves her old life behind.

Taylor meets the couple Estevan and Esperanza, undocumented immigrants from Guatemala who are frightened and traumatized by their experiences back home. They fled their home country to protect themselves and other members of an undocumented teachers’ union. Leaving Guatemala meant leaving their daughter behind, but staying there would have put the lives and freedom of their group members at risk.

Referring to Estevan's conversation with Taylor, Kingsolver writes,

He told me that the national symbol of the Indian people in Guatemala was the quetzal, a beautiful green bird with a long, long tail. I told him I had seen military macaws at the zoo, and wondered if the quetzal was anything like those. He said no. If you tried to keep this bird in a cage, it died.

Kingsolver uses the image of the quetzal to symbolize freedom. Its beauty and spirit cannot be contained in a cage, or the quetzal, like freedom itself, will die.

While traveling in a car, Taylor, a woman from the US, is having a conversation with Estevan, a man from Guatemala. Talking about characteristics of their different countries, one subject is their national symbols. Estevan asks about the alligator logo on his polo shirt, something he is just becoming familiar with, as he is new to the US. He thinks that could be the US national symbol and thinks it might be appropriate because alligators harm people—a characteristic he associated with US military policies. The quote about the quetzal bird comes next.

The conversation between Taylor and Estevan highlights differences in their knowledge about each other’s countries. Taylor mentions another bird she saw, thinking that the substance of their conversation is animals. But Estevan is more concerned with the symbolic meaning. He is trying to find out what Taylor thinks her country stands for. Rather than ask about the physical characteristics of the macaw that he might compare with the quetzal’s long, green tail, Estevan picks up on the fact that Taylor mentions the zoo. Freedom, contrasted to being in a cage, is what matters to Estevan. Having a freedom-loving bird as a symbol corresponds to the Guatemalan people’s hope for freedom. If US people already have freedom, then they do not need a symbol of hope.

In order to best understand the quote that you have given us, you need to think about the overall themes of this work and about the passage that comes just before the part that you quote.

First of all, let us look at the themes of the novel.  As the eNotes discussion of the themes (link below) says, one of the themes of the novel is human rights which

... involve personal safety and freedom, which most United States citizens take for granted.

The passage you cite is making this point.

Before the part you quote, Esteban asks Taylor if the national symbol of the US is an alligator since so many people wear it on their shirts.  This is a reference to materialism since this book was written in the '80s when Izod shirts with their alligator logo were very popular.

By contrast, Esteban says, the Indians of Guatemala had as their symbol a bird that dies in captivity.  This is symbolizing their fierce desire to be free.  This desire for freedom and human rights is why Esteban and Esperanza -- whose name means "hope" -- are in America in the first place.

So the discussion of the alligator and the quetzal is meant to symbolize the differences between complacent Americans who have their rights and care only about material goods and the oppressed, like the Indians in Guatemala, who value freedom so highly that they die without it.

What images in The Bean Trees connect with the quetzal to form a motif throughout the story?

“If you tried to keep this bird in a cage, it died.” According to this quote, being caged—without freedom—can cause something to die. If you look at the concepts of death and lack of freedom as figurative language, the “something” that dies could be a person, a skill, a trait, or just about anything. To broaden the statement, you can liken “death” to “loss.” The question becomes Where else in the novel does a lack of freedom—a limitation or restriction—cause something to die or be lost?

Here’s a generic example: A parent decides to not allow their child to play sports (the restriction, or lack of freedom). As a result, the child loses several things—not only the chance to develop athletic skills, but the chance to make friends and to learn to work as part of a team. Each loss has the potential for additional negative effects in the future.

A direct example of this is what happened to Estevan’s daughter, Ismene: Being metaphorically caged by the government’s actions—forced to either give up the names of members of the teacher’s union or lose his daughter—would have caused a loss no matter what he decided to do. As it stands, Estevan and Esperanza lost their daughter.

The theme of human rights—and the loss of them—is applicable here. Since the quetzal is "the national symbol of the Indian people in Guatemala," I'd recommend focusing on places in the text where those people have lost freedoms.