The Science Behind Mockingbirds' Mimicry

Main Insights

Arkansas, Florida, Mississippi, Tennessee, and Texas share more than just a love for college football—they’ve all selected a feathered imitator as their official state bird. Known scientifically as Mimus polyglottos, which translates to "mimic of many tongues," the Northern mockingbird can replicate the calls of cardinals, blue jays, wrens, titmice, and numerous other birds. Even more impressive are its accurate imitations of car alarms and the creaking of gates.

The Mimus polyglottos is just one of over 14 mockingbird species worldwide. Many of these birds are renowned for mimicking the sounds of other creatures, raising the question: Why do mockingbirds "mock"? What evolutionary benefit does this vocal ability provide? And do they ever cease learning new sounds?

Bird Brains

To uncover answers, we consulted biologist Dave Gammon from Elon University in North Carolina, a specialist in mockingbirds. "I began studying them more than ten years ago," he shared via email. "At the time, everyone was fascinated" by these mimicry experts, "but no one had researched their mimicry for more than a year or two."

His research into their behavior challenged an old belief. While birds like macaws and European starlings can learn new songs throughout their lives, earning them the label of "open-ended learners" in neurobiology, others are "close-ended learners," meaning they stop acquiring new songs after reaching a certain age.

Ornithologists previously believed mockingbirds were open-ended learners, but this view has shifted. Gammon analyzed recordings from 15 individual mockingbirds over several years. If these birds were continually learning new songs, their repertoires should grow with age. However, Gammon discovered that their song collections did not expand as they aged. "I think it's safe to say," Gammon notes, "... that mockingbird song-learning isn't as open-ended as many initially believed."

The cognitive foundations of bird song learning are intriguing. Eliot Brenowitz, a professor of psychology and biology at the University of Washington, specializes in the neurological development of birds. He is particularly interested in how birds acquire their vocal abilities.

For close-ended learners like zebra finches, young birds have only a year to learn all the songs and calls they’ll use as adults. After this period, their ability to learn new sounds diminishes. "In species that learn songs only as juveniles, a brain region essential for learning (called LMAN) shrinks in size and neuron count during their first year," Brenowitz explains via email. He adds that other "molecular changes" in the brain make learning increasingly difficult over time. "No one has yet examined the brains of juvenile mockingbirds, so it’s unclear if similar changes occur in their first year."

Mimicry, Uncertainty and the Scientific Process

Nature is filled with examples of animals mimicking one another. Harmless milk snakes have evolved to look like venomous coral snakes to ward off predators. Alligator snapping turtles use worm-like lures on their tongues to attract prey. So, what advantage does a bird gain by imitating the calls of another species?

The reason varies by species. The African fork-tailed drongo mimics alarm calls of other birds to frighten them away and snatch their food. Male satin bowerbirds attempt to attract mates by replicating the calls of crows, cockatoos, kookaburras, and similar birds. Those with the most accurate imitations have a higher chance of reproducing. "Imitating the vocalizations of other species may be challenging, and females may select males based on how precisely they mimic," Brenowitz explains.

The exact reason mockingbirds mimic remains unclear to scientists. Gammon notes that robins and cardinals don’t alter their behavior when northern mockingbirds copy their calls, suggesting that vocal mimicry isn’t used to manipulate other species.

An adult male mockingbird can produce up to 200 unique sounds. Interestingly, these birds also have their own original songs, distinct from those of other species. Mockingbirds tend to mimic sounds—like titmouse calls, cardinal chirps, and even car alarms—that are acoustically similar to their own vocal patterns. The reason for this preference remains unknown.

"For me, it’s still unclear whether any existing hypothesis fully explains mockingbird mimicry," Gammon states. "In science, it’s better to accept uncertainty than to be proven wrong later. Hopefully, future research will provide clearer insights."