Why are bluebirds blue?

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The evolution of plumage color fascinates Dr. Lynn Siefferman.

A behavioral ecologist at Appalachian State University, Siefferman researches variations in feather color of the Eastern bluebird – how brightness correlates with personality traits and choice of mate. Using more than 200 bird boxes in rural Watauga County, she has attracted a substantial bird population for studying mating behavior and for collecting feathers to examine in her campus lab.

Her research has been funded by the National Science Foundation and theNational Institutes of Health. She recently received the Conference of Southern Graduate Schools’ Achievement Award for New Scholars in the Life Sciences for her work.

“It’s important for us to understand evolution and how the world works, because we’re part of it,” said Siefferman, an assistant professor in the Department of Biology. “I work with a model species and ask basic, theoretical science questions.”

Her research findings

Siefferman monitors bird behavior through a combination of personal observation and video cameras focused on the nesting boxes. Through her experiments, she has found evidence suggesting the following:

  • The Eastern bluebird’s color intensity is affected by its environment, such as the amount of food it has access to and the number of hatchlings in a nest. “Anything that puts the bird in sub-optimal conditions results in duller color,” she said.
  • The more colorful males are better able to secure nesting boxes and are not challenged for the boxes by the duller males. “The brighter guys may use color to show their toughness so they’re not messed with,” she said.
  • More colorful males mate earlier and with females who have more and healthier offspring. “The females may look to color as a determination of a male’s success to function in the world,” she said.
  • More colorful males tend to be less aggressive than the duller birds, even during mating season.

“The dull birds are super aggressive and the bright guys are laid back. Why? Our prediction is that the dull guys are protective and engage in stronger mate guarding because the females tend to leave them for the brighter guys. We don’t have the answers, but we see intriguing patterns that are prompting us to research the difference between true dominance and aggression. They aren’t necessarily the same thing,” she said.

Siefferman is also expanding her research to address the role of certain hormones and whether there is a genetic basis to a bird’s personality traits. “We’re studying evolution but trying to understand the mechanisms as they happen now,” she said.

Bluebirds, which were considered rare for decades after deforestation in the early 1900s, have rebounded in population. They are now among the most common birds in North America, thanks to concerted efforts to install nesting boxes in communities and on farmland.

Siefferman started her bluebird research while working on her Ph.D. at Auburn University. She has taught at Appalachian since 2007.

Opportunities for undergraduates

Like most faculty members at Appalachian, Siefferman offers undergraduates the opportunity to assist with her research -- both in the field and inside the laboratory. Katie Pittman '09, a biology major from Raleigh, worked with Siefferman for two years, most recently helping her compare the aggressiveness of bright and dull males during mating season.

“The personal relationships I’ve had here at Appalachian are incredible,” Pittman, an honors student, said prior to graduation. “I chose Appalachian because it is a smaller, more personal school. I wouldn’t have had this opportunity to work with a cool biologist at a larger school.”

Dave Hamilton, a senior biology major with a concentration in sustainable development, said Siefferman’s "awesome" classes that include hands-on activities are preparing him well for life after graduation.

“Without experience in the field it would be impossible to identify birds and recognize their behaviors,” he said.