fascination with the diversity of life has led Stephen Pruett-Jones
again and again to ask, “Why?”
bright green wingtips, they stand out among the more subdued hues
favored by University students. They often screech during summer
mornings near the David and Alfred Smart Museum of Art and pick
berries off the quads' holly trees in the fall. They are monk parakeets,
and they are more than the stuff of campus legend.
Known for his
own colorful Hawaiian shirts, Stephen Pruett-Jones, associate professor
in ecology & evolution, the Committee on Evolutionary Biology, and
the College, has embarked on the first major biological and ecological
study of America's monk parakeet population. He wants to know whether
the monk parakeets-regarded as agricultural pests in their native
South America-could harm crops in Illinois and how they survive
the harsh Chicago winters.
of an office that comfortably accommodates a border collie named
Mik, vases of bird feathers, and an inflatable southern hairy-nosed
wombat, the 45-year-old zoologist says such questions follow his
broader line of inquiry into the evolution of animals' social behavior
and their mating systems. He also plans to expand this year his
ongoing studies of the mating rituals of the Australian fairy-wrens
and of the dark-winged damselfly.
says he couldn't resist studying the monk parakeets, given their
campus proximity and lack of academic attention. The first sighting
of Chicago's free-flying monk parakeets dates to 1973. According
to local lore, they settled in Hyde Park after escaping from a cage
at O'Hare International Airport. That rumor may be based on a documented
escape at a New York airport, Pruett-Jones says, suggesting that
the Hyde Park population more likely sprang from the escape or even
intentional release of pet monk parakeets, which, unlike some other
small parrots, have poor mimicking skills and high-pitched screams.
Adding to the birds' legend, the late Mayor Harold Washington is
said to have directed police to protect the colorful creatures that
flew outside his apartment overlooking "Parrot Park" at Lake Shore
Drive and 53rd Street.
estimates, Hyde Park's monk parakeet population has grown to about
200, with 80 nests perched on power transformers and in the trees
of Parrot Park and of Washington Park. He predicts they will be
flying all over the continental United States within the next two
decades. So far-in at least six other states, including New York
and Florida- they have inexplicably chosen parklands, suburban lawns,
and backyards with birdfeeders over croplands. "I previously thought
the monk parakeets should be controlled because an introduced species
is almost always bad for its new environment," Pruett-Jones says.
"But now I believe they are sufficiently benign in the habitats
where they now occur. They're not a pest, and they don't compete
with a native species."
With the mysteries
of the monk parakeet awaiting him, Pruett-Jones, who holds a Ph.D.
in zoology from Berkeley, returns this month from a field study
of his primary winged subject: the Australian fairy-wrens. For six
weeks, he has been tracking and observing the tiny birds-weighing
just 10 grams each-in Brookfield Zoo's Brookfield Conservation Park,
located 100 miles northeast of Adelaide in southern Australia.
For the past
seven years, Pruett-Jones has studied one particular species-the
splendid fairy-wren. He was initially struck by the contrast between
the dull brown females and the brightly plumed males who look "like
little blue gems." He also wanted to get to the bottom of why male
and female fairy-wrens raise young with one partner while continuing
to mate with others. He seeks to scientifically answer the age-old
question: "Why would it be an advantage to be socially monogamous
but sexually promiscuous?"
To do so,
Pruett-Jones and his assistants typically spend three months in
the field each year. They band the birds, record their height and
weight, and collect blood samples. Covering three square miles,
they also map the birds' territories and observe their feeding patterns
and mating rituals. Back at the U of C, Pruett-Jones and his team
then spend another nine months in the lab analyzing the blood samples
using DNA "fingerprinting." These samples hold the real keys to
the "discreet" birds' behavior, Pruett-Jones says. While the team
may be able to observe a single bird copulating as many as ten times
during the course of a field study, the DNA analysis tracks the
thousands of such liaisons actually engaged in by the bird and any
has concluded that all female fairy-wrens engage in "extra-pair
copulations," with most raising their young with the support of
a "helper" male, he cannot yet explain exactly when and why they
do this: "My hunch is that group living and family life are important
to avoid predators and that the females may not always be paired
with the most desirable reproductive males."
On this fall's
trip to Australia, the team planned to study white-winged fairy-wrens,
a species Pruett-Jones says raises even more interesting questions.
The male and female white-winged fairy-wrens, he explains, look
alike until age 4, when the genders can be distinguished by changes
in plumage color. During those first four years, females sometimes
mate with female-looking males. "I think the females are mating
with the look-alikes because the look-alikes provide better parental
care and are the better fathers," he speculates. The switch to white-winged
fairy-wrens also gives Pruett-Jones the chance to be the first to
explain the independent evolution of two variations of the species
on two islands off the western coast of Australia.
winged creature has flown into the project files of Pruett-Jones.
This past summer, he taught at the University of Michigan's Biological
Station on Douglas Lake-in the northern tip of the state's Lower
Peninsula-where he began a study of the mating rituals of the dark-winged
damselfly. He examined, in part, whether the damselflies pay attention
to the symmetry of each other's wings when looking for a partner.
"Evolutionary biologists have found that individuals in societies
are sensitive to asymmetries," he explains, and, indeed, he found
that female damselflies do tend to favor the more symmetrical males.
He now wants to find out whether the females favor the symmetrical
males because they're more attractive or because they can better
defend their territory.
discoveries may not apply directly to humans, Pruett-Jones notes,
"they help us learn about ourselves. We're all connected to animals."
And they affirm the excitement of his work. "Many aspects of diversity
in the animal kingdom relate to diversity in mating systems," he
says. "The exaggerated tail of the peacock, the bullfrog's call,
why birds sing-all of the enormous diversity of life relates to