In May of 2013, in the Cumberland Mountains of North Eastern Tennessee, Dr. Henry Streby from UC Berkeley and his colleagues from the Universities of Tennessee and Minnesota captured and equipped 20 tiny golden warblers with geo-locators to see if their migration patterns could be tracked in this way. Eleven months later, in April 2014, the scientists were celebrating the unexpected success of their pilot study after 10 of the 20 birds returned to nest – with tracking devices in tact – following a 3100-mile return trip home from Columbia, South America.
The scientists were in the field observing the birds when they received warning of the tornadoes that would soon sweep across the south and central U.S. They retreated till after the storm blew over, then recaptured five of the birds to examine their geo-locators. What they discovered was that the birds had taken cover, too: The day before the storm arrived, they flew 400 miles south to the Gulf of Mexico then back again to their nests once the storm had passed – despite the fact that they had only just returned from South America days before.
The discovery that these tiny songbirds – weighing approximately 9 grams – come pre-equipped with an early warning system opened up all sorts of research possibilities. Writing in the journal Current Biology, ecologists suggest these birds – and others – may sense such extreme events with their keen, infrasonic (low-frequency) hearing.