When faced with environmental threats like bad weather, predators or oil spills, wild birds secrete a hormone called corticosterone. Traditionally, researchers have analyzed blood samples to detect corticosterone levels in wild birds.
But recently, scientists have shown that corticosterone spikes can also be detected by analyzing bird feathers. A Tufts University study published in the May 11 online edition of "Journal of Avian Biology" confirmed the new technique as a useful way to determine avian stress response not only to sudden natural threats but also to human-caused activities that have a long-term impact on the environment, such as large construction projects or oil spills.
L. Michael Romero, professor of biology in the School of Arts and Sciences at Tufts, says the findings will be useful to conservationists. "There is a fair bit of public interest in whether human activities create stress in wildlife," says Romero, who directed the study that was led by doctoral student Christine R. Lattin. "The idea is that we can determine whether human changes will leave a record of stress in birds' feathers."
Feathers Offer Advantages Over Blood Sampling
For researchers studying stress in birds, feathers present significant advantages over blood sampling. Scientists can obtain feather samples by collecting naturally-molted feathers from the nest without having to handle birds.
Also, blood samples provide only a snapshot of corticosterone in the blood at the moment the blood sample is drawn. Feathers, however, reflect hormone levels during the time it takes feathers to grow, says Lattin.
"This is important in understanding the long-term impacts of stressors on animals, because stress hormones are mostly beneficial in the short term, and only become a problem when they are at high levels for a sustained period of time," Lattin says.
To test the hypothesis that corticosterone levels in birds' feathers correspond to levels in birds' tissues, the researchers collected feathers from captive European starlings and compared the feather cortisone levels of starlings with and without experimentally-elevated cortisone (via a small capsule implant)They also collected blood samples from each bird three times during the experiment: before implantation and three and five days after implantation.
The researchers analyzed the feathers in two ways. They divided one batch into subgroups that differentiated three stages of growth—before, during and after implantation.
In the second part of the study, the scientists wanted to determine if feathers from the same bird would have similar corticosterone levels. To do this, they selected two feathers from the same bird.
An analysis of the feathers yielded several findings. The nine starlings implanted with corticosterone had significantly higher levels of the hormone in their feathers during the study period than the other birds. Also, the scientists found no difference in corticosterone levels between feathers taken from the same bird, indicating a consistency in feathers grown at the same time.
Romero and Lattin are collaborating with other researchers to see if this technique can be applied to preserved bird specimens at the Smithsonian Institute in Washington, D.C. Feathers may be a way to determine whether birds that lived in the wild decades ago lived in stressful environments.
"This opens up the possibility to use museum specimens to look at how changes in the environment may have affected the birds," says Romero.
Elevated Corticosterone is Related to Deformities in Feathers
In previous experiments, the scientists found that feathers from birds implanted with corticosterone in had lighter, weaker feathers. Lattin says that the results suggest that elevated corticosterone levels could impact birds' health.
The research was funded by a grant from the National Science Foundation.
Christine R. Lattin, J. Michael Reed, David W. DesRochers and L. Michael Romero
Article first published online: 11 MAY 2011 | DOI: 10.1111/j.1600-048X.2010.05310.x
Tufts University, located on three Massachusetts campuses in Boston, Medford/Somerville, and Grafton, and in Talloires, France, is recognized among the premier research universities in the United States. Tufts enjoys a global reputation for academic excellence and for the preparation of students as leaders in a wide range of professions. A growing number of innovative teaching and research initiatives span all Tufts campuses, and collaboration among the faculty and students in the undergraduate, graduate and professional programs across the university's schools is widely encouraged.
Alex Reid | EurekAlert!
Clock stars: Astrocytes keep time for brain, behavior
27.03.2017 | Washington University in St. Louis
Cryo-electron microscopy achieves unprecedented resolution using new computational methods
24.03.2017 | DOE/Lawrence Berkeley National Laboratory
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
27.03.2017 | Health and Medicine
27.03.2017 | Life Sciences
27.03.2017 | Earth Sciences