16/03/2007
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Metal in Feathers Could Provide Bird Flu Clues

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Sedge Warbler: The team measured strontium isotope levels in the feathers of the Sedge Warbler, and mapped how this changed with geographic location (Photo: Peter Simpson)

Measurements of different forms of the metal strontium found in bird feathers could unravel mysteries of their migration patterns and help predict the arrival of avian carried diseases such as bird flu.

The news is reported in the latest edition of the Royal Society of Chemistry's Journal of Analytical Atomic Spectrometry.

Concern about the spread of bird flu means there is an urgent need to find better ways of monitoring the movements of migrating birds.

Dr Laura Font and a team at the University of Durham have developed a technique based on thermal ionisation mass spectrometry (TIMS) that can measure very low concentrations of strontium isotopes in bird feathers (different isotopes of an element have the same number of protons but different numbers of neutrons in their nucleus).

The team measured strontium isotope levels in the feathers of the Sedge Warbler, and mapped how this changed with geographic location.

Dr Font said: "The routes of migrant birds have previously been studied using a variety of techniques, such as marking individuals with metal leg rings, radio or satellite tags, or simply counting bird numbers at migratory stop-over points."

"But these labour-intensive methods generate relatively little data and often do not reveal the origin of individual birds."

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Migratory birds regularly renew their feathers, often prior to migration - and the feathers tend to reflect the unique "isotopic signature" of the region in which they were grown.

Although analysis of carbon, nitrogen, hydrogen and oxygen isotopes can give a rough idea of the birds' origin, strontium isotope ratios in the bones, claws and egg shells of birds tend to provide a much more precise location.

Unfortunately, bone analysis is too invasive for routine use. But Dr Font's technique has finally made accurate analysis of strontium in feathers a viable option for tracking birds.

Dr Font said: "By determining migration pathways, the arrival of potential vectors of diseases from infected areas can be anticipated.

"Knowledge of migratory routes also helps evaluate the likelihood that individual avian influenza outbreaks could be related to migratory movements rather than anthropogenic activities, such as poultry movements, which are believed to be the main vector of avian influenza in most outbreaks."