Birds of a FeatherBy Melissa Lutz Blouin
Graduate student Sara Ress has transformed her love of birds into action. During her undergraduate years at Auburn University in Alabama, the zoology major and trained falconer worked in a raptor rehabilitation facility. During those years, she also spent a summer working at a zoo in Costa Rica. Now her interest in raptors has brought her to the University of Arkansas, where she pursues her passion through research.
Ress spent last fall in the Florida Keys, working with Hawk Watch International to trap and tag raptors on their migration pathway, which brings them over the islands. When raptors fly south for the winter, they generally avoid large bodies of water. Thus, the American kestrels, broad-winged hawks, Coopers hawks, sharp-shinned hawks, northern harriers and other raptors fly down the narrow strip of the Florida Keys before heading over the Caribbean, creating a concentrated pathway where researchers can study the birds.
The research Ress is conducting focuses on a novel approach to tracking raptor migration patterns by studying their feathers. Although researchers and bird lovers have known about north-south migration for a long time, many of the specifics of bird migration remain unknown.
"The big question is, where are the birds migrating through the Keys coming from?" said Kimberly Smith, professor of biological sciences and Ress’ adviser. "No one has looked at that in a meaningful manner."
The feathers of juvenile birds may hold the answer. It turns out that ratios of a hydrogen isotope called deuterium, found in water, vary from region to region and at different altitudes. Researchers have mapped these variations and can pinpoint regions where different isotope ratios appear. Animals that drink the water in a particular area pick up the isotope ratio signal, and the raptors that eat those animals also pick up the signal, which then is absorbed in their feathers. Because the juvenile birds have never migrated before, their feathers contain the isotopes of their birthplaces.
In Florida, Ress collected feathers from about 170 juvenile birds. She hopes the feathers will provide information about the young birds’ birthplaces.
"By doing this, we’ll be able to link their breeding and wintering grounds," and possibly pinpoint population changes, Ress said.
Ress has the feathers she collected last summer and feathers from five previous seasons—feathers from about 1,800 birds in all. From these feathers she will select about 500 that she will clean, dry, weigh and pack into a capsule to be combusted into gases. She will use a mass spectrometer at a laboratory in Canada to examine the samples. The instrument will measure the hydrogen-deuterium ratios, which then can be linked back to the individual bird’s place of origin.
Ress won the Morley Nelson Fellowship, a highly competitive grant from the Conservation Research Foundation to support work in raptor research, management and conservation. Smith said the award reflects on her past and present work.
"Sara had an outstanding undergraduate career at Auburn," Smith said. Her honors thesis was published in the "Journal of Raptor Research," the top journal in the field.
Ress isn’t certain about what she wants to do after graduation, but
she knows it will involve working with animals, and she wants it to be
"I hope one day to be able to educate, whether working as a biologist for the government or a non-profit group, working at a zoo or rehabilitation center, or working in some sort of environmental education program," she said. "A favorite quote of mine is, ‘In the end we will conserve only what we love, we will love only what we understand, and we will understand only what we are taught.’ I believe in this strongly."
Location of research:
Florida Keys, in Curry Hammock State Park on Long Point Key.