"The effects [Hore and colleages] see are matching exactly what you would expect from theory," Ritz said.
The scientists report the finding in tomorrow's issue of the journal Nature.
Hore's team is now trying the same lab experiment on molecules called cryptochromes—photoreceptors that scientists suspect are responsible for birds' chemical compasses.
A similar result, Hore said, would be another step closer to validating the theory.
"Beyond that, you would want to show that cryptochomes are sensitive to magnetic fields in birds," he said.
According to UC Irvine's Ritz, these new experiments will help guide scientists who work with birds as to where and how to look for a chemical compass.
Some scientists believe a second theory: that a magnetic mineral called magnetite in their bodies helps animals orient themselves in Earth's magnetic field.
(Related: "Magnetic Beaks Help Birds Navigate, Study Says" [November 24, 2004].)
Other experts, such as Hore, think both mechanisms may be at play.
"This will all be resolved in the next five to ten years," Ritz said.
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