A tool to measure stress hormone in birds -- feathers

Aug 16, 2011

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 confirmed the new technique as a useful way to determine avian 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 . "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, provide only a snapshot of corticosterone in the blood at the moment the blood sample is drawn. Feathers, however, reflect during the time it takes feathers to grow, says Lattin.

"This is important in understanding the long-term impacts of on animals, because 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 . Lattin says that the results suggest that elevated corticosterone levels could impact birds' health.

Explore further: Endangered clouded leopard kittens born in Miami zoo

More information: DOI: 10.1111/j.1600-048X.2010.05310.x

Related Stories

Some birds may use their feathers to touch

Feb 15, 2010

(PhysOrg.com) -- A new study of auklets suggests the birds use their ornamental feathers in much the same way as cats use their whiskers: to feel their surroundings.

'Nervous' birds take more risks

Oct 26, 2007

Scientists have shown that birds with higher stress levels adopt bolder behaviour than their normally more relaxed peers in stressful situations. A University of Exeter research team studied zebra finches, which had been ...

What limits the size of birds?

Jun 16, 2009

Why aren't birds larger? Fifteen-kilogram swans hold the current upper size record for flying birds, although the extinct Argentavis of the Miocene Epoch in Argentina is estimated to have weighed 70 kilograms, the size of ...

Evidence Neanderthals used feathers for decoration

Feb 23, 2011

(PhysOrg.com) -- Researchers studying a large deposit of Neanderthal bones in Italy have discovered the remains of birds along with the bones, and evidence the feathers were probably used for ornamentation. ...

Ancient Birds Flew On All-Fours

Sep 26, 2006

The earliest known ancestor of modern-day birds took to the skies by gliding from trees using primitive feathered wings on their arms and legs, according to new research by a University of Calgary paleontologist. In a paper ...

Recommended for you

Clues to aging from long-lived lemurs

17 hours ago

When Jonas the lemur died in January, just five months short of his thirtieth birthday, he was the oldest of his kind. A primate called a fat-tailed dwarf lemur, Jonas belonged to a long-lived clan. Dwarf ...

Cats relax to the sound of music

21 hours ago

According to research published today in the Journal of Feline Medicine and Surgery by veterinary clinicians at the University of Lisbon and a clinic in the nearby town of Barreiro in Portugal, music is likew ...

Fruit flies crucial to basic research

23 hours ago

The world around us is full of amazing creatures. My favorite is an animal the size of a pinhead, that can fly and land on the ceiling, that stages an elaborate (if not beautiful) courtship ritual, that can ...

Crete's mystery croc killed by cold snap

23 hours ago

A man-eating crocodile that became an attraction on the Greek island of Crete last year after its mysterious appearance in a lake has died, probably of cold, an official said Monday.

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.