Monday, February 28, 2005

Birds Breathalyzed But Not For Drinking And Flying

According to the Washington Post migrating songbirds stop periodically to eat and store energy for the next leg of their journeys. Now, thanks to a tiny, three-valve "bird breathalyzer," scientists can figure out what they're eating, and it's not always what seems obvious.

Working on Block Island off the Rhode Island coast, Brigham Young University ecologist Kent A. Hatch led a team that sampled the breath of migrating white-throated sparrows and yellow-rumped warblers that stopped, ostensibly to feed on bayberries, before continuing south to the Caribbean. The research was reported in the current issue of the journal Oecologia.

Hatch uses his breathalyzer, which shows what a bird has been eating.

The team caught the birds with fine-mesh nets, put the mask on and let them breathe and re-breathe the oxygen before releasing them. They drew off the breath sample with the syringe and analyzed it for isotope content in a mass spectrometer.

Hatch said the warblers ate bayberries exclusively for the previous 12 hours, the period covered by the breathalyzer. But the sparrows' diet also included corn, millet or sorghum -- probably from bird feeders, he said, because Block lsland is not known for agriculture.

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