Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Isotopes from feathers reveal bird migration

06.11.2003


Using naturally occurring patterns of stable-isotopes created by weather and plants, Jason Duxbury of the University of Alberta and his colleagues are tracking the migration routes of birds of prey. Their work on the summer origins of migrating and wintering Peregrine Falcons and Burrowing Owls has shed new light on what has previously been the secret, non-breeding half of the birds’ lives.



By analyzing stable isotopes of hydrogen, carbon, and nitrogen in bird feathers, Duxbury has been able to trace Burrowing Owls wintering grounds in southern Texas and central Mexico, as well as migrating Peregrine Falcons caught on the gulf coast of Texas, back to their breeding grounds in Canada.

The principle behind the work is simple: birds are what they eat. And what birds eat while growing feathers on the breeding grounds contains isotopes of hydrogen, carbon, and nitrogen. These vary in predictable patterns across North America.


Duxbury will be presenting a paper on his work on Wednesday, November 5, at the annual meeting of the Geological Society of America in Seattle, WA. Scientists there are exploring the evolving interface between isotope geochemistry and ecology.

Hydrogen and its heavier version, the isotope deuterium, are both naturally found in molecules of rain water. But as the cycle of evaporation and precipitation repeats across North America and over mountainous regions, the heavier deuterium isotopes get left behind. That creates well-mapped hydrogen/deuterium trends across the continent, Duxbury explains.

"There is a well known gradient of depleting deuterium/hydrogen ratios from the Gulf of Mexico and the Atlantic Ocean across the eastern part of North America," said Duxbury. As you get near mountains there is also a noticeable elevation effect that reflects how changes in elevation also cause precipitation cycles.

The hydrogen isotope signature of animals is essentially the isotope signature found in the water and food they eat. Furthermore, the isotope signature found at the bottom of the food chains can be passed up to the top of food chains. The result is that isotopic signatures in the feathers of the top predators reflect the area where the food was consumed while the feathers were grown.

Carbon isotopes, also found in feathers, vary with latitude due to different growing conditions for plants across the continent. Even nitrogen isotopes can help track birds, though nitrogen isotopes variations are not found in predictable patterns. The application of nitrogen-rich fertilizers in agricultural areas can also alter nitrogen isotope ratios, Duxbury explains.

To collect the feathers for analysis, Duxbury and his colleagues rely on other researchers across North America. "Since 1995 I’ve had other researchers who were banding birds gather feathers all across North America," Duxbury said.

In order to get a local isotope baseline for a bird population the researchers first gather feathers from nestlings at their nest sites. Then they gather feathers from birds on migration or on their wintering grounds to trace them back to the isotope baseline based on the nestlings.

In the case of Burrowing Owls, the stable isotope technique has traced unbanded owls wintering in central Mexico back to Canadian breeding populations, said Duxbury. Subsequent analyses have also revealed that Burrowing Owls disperse more widely between breeding seasons than previously thought. That discovery, in turn, can be applied to population models used in the conservation of Burrowing Owls.

This relatively new technique will not replace banding, says Duxbury, since it cannot trace a bird to an exact location. However, the recovery of a banded bird is very rare event, and so it takes decades to accumulate data. Stable-isotope analysis is providing similar dispersal and migration data, but at a far greater rate. In essence, every bird that is captured for a feather sample is equivalent to a band recovery, Duxbury says.

"Essentially, it’s not as good as getting a band return, which gives you A to B," says Duxbury. "You can’t say exactly where a bird’s origin was, but you can narrow it down to a region. For instance, with an isotope signature we can get it back to southern Alberta, whereas a band can get it to an exact nest location."

Satellite telemetry is by far the most accurate method of tracking birds. However, it comes with a hefty price. In addition, technology has not developed satellite transmitters small enough for Burrowing Owls, says Duxbury.

Ann Cairns | EurekAlert!
Further information:
http://gsa.confex.com/gsa/2003AM/finalprogram/abstract_66548.htm
http://www.geosociety.org

More articles from Earth Sciences:

nachricht Large-Mouthed Fish Was Top Predator After Mass Extinction
26.07.2017 | Universität Zürich

nachricht Strength of tectonic plates may explain shape of the Tibetan Plateau, study finds
25.07.2017 | University of Illinois at Urbana-Champaign

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Carbon Nanotubes Turn Electrical Current into Light-emitting Quasi-particles

Strong light-matter coupling in these semiconducting tubes may hold the key to electrically pumped lasers

Light-matter quasi-particles can be generated electrically in semiconducting carbon nanotubes. Material scientists and physicists from Heidelberg University...

Im Focus: Flexible proximity sensor creates smart surfaces

Fraunhofer IPA has developed a proximity sensor made from silicone and carbon nanotubes (CNT) which detects objects and determines their position. The materials and printing process used mean that the sensor is extremely flexible, economical and can be used for large surfaces. Industry and research partners can use and further develop this innovation straight away.

At first glance, the proximity sensor appears to be nothing special: a thin, elastic layer of silicone onto which black square surfaces are printed, but these...

Im Focus: 3-D scanning with water

3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects

A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

 
Latest News

CCNY physicists master unexplored electron property

26.07.2017 | Physics and Astronomy

Molecular microscopy illuminates molecular motor motion

26.07.2017 | Life Sciences

Large-Mouthed Fish Was Top Predator After Mass Extinction

26.07.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>