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Brainy Bonnie

She's a longtime participant in research at the National Zoo—and she's a charmer.

by Dan Stone

Most parents consider themselves above favoritism. The same goes for the orangutan keepers at the Smithsonian’s National Zoo. But when you work with an orangutan as intelligent and charismatic as Bonnie, a 32-year-old female, it’s tempting to play favorites.

Bonnie’s keepers say her “complex personality” fascinates all who meet her. “She is very observant and never misses a thing,” says Erin Stromberg, a Great Ape House keeper. “She will often come up to the glass and study the visitors on the other side. When there are events on the [Zoo’s] Great Meadow, she likes to climb the O Line and study every facet of what is happening.”

In addition to being observant, Bonnie is playful, creative, sensitive, and people-oriented, according to her keepers. While confident with people, she is more submissive with the other orangutans. Her excellent maternal skills came in handy when sub-adult Kyle arrived at the Zoo a few years ago. Bonnie adopted and nurtured him though this time of transition.

Bonnie the orangutan

Bonnie is a beloved orangutan and longtime research subject at the Zoo. (Ann Batdorf/NZP)

Just like a human, Bonnie has her idiosyncrasies. She will imitate the keepers’ activities, cleaning the glass and sweeping the floor for attention. When she is anxious, she will use pieces of a sheet to roll up chewed food or other debris, then chew on her creation, says Lisa Stevens, the Zoo’s curator of primates and pandas.

Science Subject

Over the years, Bonnie has been a long-term partner in cognitive research at the Zoo, participating in several studies. The first began in 1993, when Robert Shumaker, coordinator of the Orangutan Language Project, initiated language research with the National Zoo’s orangutans.

A current study looks at orangutan memory and decisionmaking, headed up by Karyl Swartz, a Smithsonian Research Associate from the Great Ape Trust of Iowa. For the past ten years, Bonnie and her fellow orangutan Iris have participated in this research program. Today, all six of the Zoo’s orangutans are involved in the project.

Swartz is trying to discover whether orangutans develop an organizing strategy for remembering long lists. Her study uses a computer touch screen to test the orangutans’ ability to remember the order in which they were shown certain pictures.

According to keepers, Bonnie is one of the brightest and most consistent primates at the Zoo. “Unlike many of the other orangutans, Bonnie is very thorough when she participates in the study,” says Stromberg, who assists with data collection. “Some of the others are less persistent with the tests, but Bonnie will keep trying until she is successful. And she doesn’t like to make mistakes.”

Bonnie is also the feature of a recent scientific paper on which Stromberg is a co-author. The study focuses on Bonnie and her unusual ability to whistle. After hearing a keeper whistling, Bonnie began to mimic the sound on her own. Whistling isn’t a sound in an orangutan’s repertoire, and Bonnie’s spontaneous ability to copy this human vocalization demonstrates that some apes can learn sounds from another species. The findings help scientists better understand the evolution of human speech.

Bonnie and Friends

Born in 1976 at the Albuquerque Zoo, Bonnie was raised in a nursery. She arrived at the National Zoo in December 1980 and is the mother of Kiko. Weighing 142 pounds, Bonnie lives at the Great Ape House and Think Tank with five other orangutans—three females and two males.

Along with male Kiko and females Iris and Lucy, Bonnie is a
hybrid orangutan. The Zoo’s other two orangutans—a male, Kyle, and a female, Batang—are Bornean.

Bonnie has many distinguishing features. Along with a large
belly, she has a bulbous forehead and a beautiful dark red coat. When the Zoo’s O Line was introduced in 1994 for the orangutans to travel between the Great Ape House and Think Tank, Bonnie was one of the first to use it. Most unique to Bonnie is that when traversing the ground, she chooses to walk on two feet like her human counterparts.

Read main story: "What Are You Thinking?"