Deep in a North Carolina marsh, a lone swamp sparrow sits on his perch in the middle of the water. Hes singing his usual song. But hes also aggressively flapping one wing, trying to incite a nearby male into action. Onlookers are watching just to see what happens.
However, this is no ordinary territorial scuffle. This is bird research. The sparrow on the perch is a robot, and the chief, hip wader-clad onlooker who is also in control of the robots movements is Steve Nowicki, Ph.D., a biology, psychology, and neurobiology professor at Duke University. Hes testing whether the wing flap will actually prompt a fight.
According to Nowicki, birdsong and signaling have a surprisingly close relationship with human speech.
Its an unexpected and remarkable model for human speech control, development and perception, he said. Birds also learn their songs in much the same way humans learn to speak, and thats an unusual trait. They have to learn their language from their parents.
His research, though, isnt about merely studying how birds behave and communicate. He and his team watch signals and behaviors; they run simulations and analyze hormones; they record neurons and assemble protein sets. Theyre deciphering how birds promote their survival and reproductive success. In short theyre studying evolution, past and present.
Nowicki, who is also dean and vice provost of undergraduate education, was almost the bird researcher who wasnt. As a student at Tufts University in Boston, he was a declared music major. Late in his collegiate career, he discovered a love of biology particularly the brain and behavior and raced to complete a major in the subject. He then pursued his graduate degree in neurobiology at Cornell University.
It was there he was first introduced to the siren song of birds. When it comes to communicating, birds have far less to say than humans. But they express themselves in equally complex ways, Nowicki said.
Humans use complicated signal communication, and we use an array of sounds to create words that have rich meanings, he said. When you look at sparrow songs the number of notes per second and the frequency its just as complicated as human speech. Theyre just not saying much.
All the same, theyre getting their points across.
In addition to the aggressive response the swamp sparrows wing flap provokes, the absence or introduction of song or even a physical attribute can prompt birds to behave differently, Nowicki said.
Birds, like most animals, are territorial and will, in most cases, defend their turf. But how will neighboring birds respond if a battle ensues? Will they come to help or avoid the fight? Will they treat the male differently if he loses to the interloper? Researchers can test this reaction, Nowicki said, by removing a bird from its environment, playing a recording of another males song, and, then, reintroducing the bird to see how the others respond.
Its interesting to see what happens, because no one wants a floating male in the neighborhood, he said. Research has shown that with some birds, peer birds are more wary of the winner, but they might also try to encroach on a losers territory.
And, just as with other species, birds can use their physical attributes to signal to and communicate with each other. For example, a trait, such as a bright red neck and throat commonly seen in the male house finch, can broadcast a birds prowess or superior qualities. The red-throated male finch does attract more females, Nowicki said, but it isnt because of the color. The pigment comes from a carotenoid-rich diet that gives these males a stronger immune system, making them better mates.
Male song sparrows use their song repertoire in much the same way. The more songs they learn and exhibit, the more attractive they are to females. The reason, Nowicki said, is that birds with larger song selections appear to be smarter. They simply learn songs faster.
Males who sing better have better developed brains, and in theory that makes them better mates, he said. Were still working out why having a better brain for learning song is better for the female, but its clear females prefer these males as their mates.
Impact on human activity
Understanding the role and importance of birdsong and signaling doesnt shed much light on the evolution of human communication, but knowing what songs and signals mean to birds can directly affect human choices and behavior.
For example, researchers have evidence that stress directly affects a birds ability to develop song, which can ultimately impact pair bonding and mating. If scientists study the way birds living in both polluted and pristine environments sing, the data could play a role in accurately evaluating ecosystem health.
This knowledge can also impact wildlife preservation efforts. It isnt enough to allocate a certain amount of space to a population based only on the number of animals surveyed. There are often other factors at work, Nowicki said. In the case of the small warbler ovenbird, its important to know that females wont be setting in an area with fewer than 10 males. This type of information can significantly alter conservation efforts, he said.
Regardless of how the research of birdsong is used, Nowicki said, his work constantly reminds him of how intertwined birds and music are with our surroundings.
I keep coming back to birdsong not simply because its a good model, Nowicki said. When I wake up in the morning and hear birds singing, its part of the wonderful aesthetic world we live in, and my job to learn more about it is a privilege.