A tiny yellow and brown bobolink sat frozen in scientist Noah
Perlut's hand, the bird's head caught between his middle and second
Her bright black eye darted from side to side as Perlut's
assistant, Jenna Cava, used Kevlar thread to tie a little package
to the bird's back.
"A little tighter, but not too tight," Perlut said. Cava dabbed
glue on the knots to hold the "backpack" secure.
The backpack, about the size of a pencil eraser, carries a light
sensor called a geolocator. When the bird flies south this fall,
the tiny device will record the intensity and timing of light
levels each day.
If Perlut can recapture the bird next spring, the data on the
changing length of daylight will allow him to calculate each day's
latitude and longitude and thus create a map of her 12,000-mile
Geolocation is just one of several ways research in Shelburne
and Charlotte hay fields has begun to reveal, and to unravel, the
mysteries of bobolinks, those yellow-capped monarchs of spring-time
Bobolinks are in steep decline in Vermont, where development and
changing farm practices have made it more difficult for the
grassland songbird to nest and safely fledge its young.
Bobolinks would be missed. Their bubbling song brings meadows
alive and their aerial acrobatics during mating are well known to
birders and farmers.
"They are so showy, with that yellow head and their bobbly
bubbly song," said Sarah Cayea of Essex, who came to know the bird
on horseback rides as a child and who now is one of Perlut's summer
assistants. "They are an essential aspect of Vermont for me."
Almost no one knows bobolinks as well as Perlut, who began his
research here as a University of Vermont graduate student 12 years
Although he is now an assistant professor at the University of
New England in Biddeford, Maine, he returns each spring to catch
and band bobolinks and to ask new questions about the species.
Twelve years of research on a single species in a single area is
extremely unusual, UVM biologist Allan Strong said. It allows
Perlut to ask, and perhaps answer, tough questions about bobolink
behavior and genetics, because he has captured several generations
"The first word to describe Noah is tenacious," Strong said. "He
knows what every single bird in that field is doing. He knows some
of these current residents' parents, grandparents and even
great-grandparents… That is rare, extremely rare."
A bobolink in the hand is a wonder; one is immediately struck by
its beating heart that's scarcely protected by translucent skin and
Each bird weighs about an ounce, yet these durable little
creatures are able to fly 6,000 miles to Argentina in the fall,
then return unerringly to this field or one nearby the following
This morning, gauze-like nets strung in the field have yielded a
bumper crop of birds. Student assistants untangle the birds gently
from the webbing and bring them to Perlut in soft cloth bags.
Perlut sits cross-legged in the grass, wearing a snug watch cap,
fleece jacket and waterproof pants as protection against an
unusually cool breeze and morning dew. A fishing tackle box holds
thread, bands, glue and other equipment.
He has been capturing birds in this field for so long that each
bobolink he plucks from a bag already wears colored bands attached
in previous years.
One of the first birds to wear a geolocator was born in this
field. When ornithologist Roz Renfrew analyzed the data the bird
carried back from his 2009-2010 migration, she discovered that
during his return he had flown from Venezuela to the Bahamas, a
1,100-mile trip, in a single day.
This research is possible because of an earlier important
finding of the Shelburne research: Apparently alone among mainland
songbirds, bobolinks return to their natal fields, or ones nearby,
to breed. That means Perlut is able to study the entire life
history of a bobolink.
Perlut calls the returned fledglings "birthday birds," because
he recaptures them roughly on their birthday, and "when we find
one, it's like unwrapping a present."
This bobolink pattern allows him to consider the characteristics
and behaviors that are linked to a fledgling's survival, its
ability to make the round-trip migration and to mate and raise
young of its own.
It is that reproduction down several generations that defines a
successful genetic line.
"When you have kids, you haven't proven fitness. You prove your
fitness when you have grandkids: you have produced children that
can produce children," Perlut says.
This year he hopes to attach geolocators to at least one parent
and one offspring from each nest his team is able to locate.
"Does the nestling migrate at the same time and to the same
place as the parent?" he asks. The assumption has been that, for
small birds that migrate by the millions, "each individual is
on his own," not traveling in a family group.
Is that truly the case?
Much of Perlut's research is aimed at increasing scientists' depth
of knowledge about bobolinks, but work he has done with UVM's
Strong has had broader practical results.
Early on, they discovered that when farmers take repeated hay
crops from a field, which they often do, bobolinks in that field
fledge zero young.
But if the first crop hay is cut early, say, before June 1, and
then the field is left untouched for 65 days, the birds will have
enough time to build a second nest and raise their young.
Trouble is, farmers, particularly dairy farmers, pay a price for
that 65-day delay because the second cutting of hay will have less
Perlut's and Strong's findings led to an experimental U.S.
Agriculture Department conservation program that paid farmers $135
an acre to delay that second cut. The program was particularly
attractive to farmers who raise hay for horses, which can thrive on
About 1,300 Vermont acres were enrolled in the program, until
the government dropped the incentive to $86 an acre and now has
found no takers. This year Strong and a Connecticut professor are
studying whether private fundraising can generate enough money to
protect some bobolink nesting grounds.
Perlut's head is always full of dozens of bobolink questions he
would like to answer, from whether bobolinks choose the same mates
year after year (and whether fidelity affects reproductive success)
to whether the shrinking of the yellow head patch on aging male
birds affects their success with females.
"In an ideal world, I'd keep on this project forever," said
Perlut during one of his morning visits to the field.
Though the bobolinks are research subjects, Perlut, the scientist,
is not above waxing poetic. "They are so interesting and
mysterious, from this spectacular migration to the joy of their
song and dance in the air," he says of the birds.
"I can't imagine a summer not full of bobolinks."
Candace Page is a freelance journalist in
Photo by Candace Page
Photo courtesy of Professor Allan Strong, University of