Susan Smith Conducts Chickadee Research
in Mount Holyoke's Backyard
By Janet Tobin
When it comes to the black-capped chickadee, one of North America's most prevalent and best-loved birds, professor Susan Smith wrote the book-literally. Smith's The Black-Capped Chickadee-Behavioral Ecology and Natural History is considered the definitive scholarly guide to the species. Dubbed "the doyenne of chickadee research" by National Wildlife magazine, Smith has gained an international reputation for her groundbreaking research on the social behavior of black-capped chickadees.
And while many Western biologists who conduct lengthy animal behavior studies must live in remote corners of Africa or Asia ˆ la Jane Goodall, Smith has spent the past two decades observing her feathered subjects in South Hadley backyards and woodlands right across the street from her office in Clapp Lab. While primates and other large animals might appear
to be more exotic research subjects than the ubiquitous chickadee, these small birds' behavior is as interesting and complex as that of their furry
and more-studied cousins.
An ornithological prodigy, Smith has been "fascinated by anything with feathers" since she was a girl and has lost little of her childhood enthusiasm. Despite her current stature in the scientific community, Norman Wait Harris and Emma Gale Harris Foundation Professor of Biological Sciences Susan Smith's discussion about chickadees is often punctuated by the words "very neat."
She first remembers spotting chickadees as a fifth-grader walking to school and rushing to her classroom's Peterson's Guide to identify her find. (Some forty years later, Smith would write the black-capped chickadee entry for another guidebook, The Birds of North America.) Smith's parents soon gave her a pair of binoculars, and much of her girlhood was spent identifying birds and learning their songs.
When Smith was a teenager, her mother arranged for her to meet the head of the University of British Columbia's zoology department. "When he told me that one could study zoology, teach, and work with birds, I was thrilled," recounts Smith. "From then on, I knew what I wanted to do."
What Smith has done for the past twenty years, in addition to teaching, and writing books and articles on chickadees, is to conduct one of the few long-term studies of a chickadee population on this side of the Atlantic, making major contributions to research on the social dynamics of winter flocks of the species.
Chickadees are ideal subjects for research, according to Smith, since
they are fairly tame, readily come to feeders, and don't migrate. "The chickadees that bred in your neighborhood last summer will remain through
summer heat and winter cold, for as long as they live," she notes.
Each fall finds Smith color-banding as many chickadees in her study area as possible, usually seventy to one hundred birds. To do so, she gently catches them with nylon "mist nets," attaches a unique combination of colored bands to both legs, measures wing and tail length, notes tail shape, and releases the birds. Smith can then identify each banded chickadee and is
able to make deductions based on her observations of the birds' behavior.
Observations include the fact that chickadees live in winter flocks, stable groups of between four and fourteen birds that stay together in the same home range all winter. Flocks have linear pecking orders: the top-ranked bird can chase every other member of the flock from a feeder; the second-ranked bird chases all but the top-ranked bird, and so on.
Smith has noted that age and sex determine rank, and rank can change. She discovered that in winter, most males rank above most females, but the reverse is true in during spring breeding season. Perhaps Smith's most important research finding, however, is that "when it comes to surviving the winter, inter-sex rank is not important. All that matters is within-sex rank. In other words, the top-ranked males and the top-ranked females are the ones who do best," she said.
In the mid-1980s, Smith noticed that "floaters" move from one flock to another, waiting to take the place in the dominance hierarchy (and the mate) of any high-ranking chickadee who has perished. In spring, flocks break into pairs, each of which will attempt to defend its breeding territory. At the end of breeding season, young birds disperse and settle into new winter flocks.
Interestingly, Smith has observed that some chickadees seem to predict how well they will survive in a few months' time. "During fall seasons that come before severe winters, fewer young birds join flocks, whereas during autumns that precede winters with good chickadee survival rates, more young birds settle into flocks," she said.
As a professor at a women's college, it seems only natural that Smith has made discoveries about female chickadees. (Most researchers focus on "male-oriented questions," Smith notes.) One finding, published in the journal Behaviour and later picked up by the New York Times and other media, dispelled the commonly held notion that the male of the species selects his mate. According to Smith, a female chickadee with a lower-ranked mate may actively seek out "better genes" for her offspring by pairing with a male with a higher ranking. In the article, Smith also notes that females paired with top-ranked males seldom mate with other males. In short, the female chickadee chooses her mate based his rank within the group.
With all her close attention to the intricacies of chickadee social patterns, Susan Smith gives deeper meaning to the word bird-watcher. She is looking forward to celebrating a quarter-century of her chickadee study in the year 2004.
Photos courtesy of Susan Smith