In the study of ecology, it's long been known that animals have a sort of sixth sense above and beyond what humans can perceive. Perhaps through the aid of their keen senses of smell or their abnormally acute sense of hearing, animals such as dogs are able to sense the presence of cancers, the onset of seizures, and even changes in the climate. But in a new study led by UC Berkeley ecologist Henry Streby, it's birds that are sensing a change. Golden-winged warblers to be exact.
The small golden-blazed birds may not normally be of much interest to ecologists and climatologists in the field, but what Streby and his colleagues discovered was that the little birds may reveal an early-warning system that a massive storm is near. Inhabitants of the mountains of eastern Tennessee, the golden-winged warblers fled their breeding grounds suddenly last April 2014, only two days before the arrival of a powerful supercell storm system, sweeping through the central and southern United States generating 84 confirmed tornadoes in the process. Intrigued by the birds' behavior and their successful warning system, Streby as a National Science Foundation Fellow worked in collaboration with biologists at the University of Tennessee, the University of Minnesota and the U.S. Geological Survey to not only track down the birds, but also try to reveal how they were able to sense the changing climate.
"It is the first time we've documented this type of storm avoidance behavior in birds during breeding season" Streby says. "We know that birds can alter their route to avoid things during regular migration, but it hadn't been shown until our study that they would leave once the migration is over and they'd established their breeding territory to escape severe weather."
"The warblers in our study flew at least 1,500 kilometers (932 miles) total to avoid a severe weather system. Then they came right back home after the storm passed."
The study published this week in the journal Current Biology, described the "evacuation migration" of the warblers, though pointed to an unexplained phenomenon or sense that researchers were unable to confirm at the time. Though the birds evacuated when the storm was still 250-260 miles away, local cues to the changing climate or onset of the storm remained absent-such as changing temperatures, wind speed and atmospheric pressure which meteorologists use to estimate the presence of a storm. And Streby, along with his fellow researchers, are still seeking answers that may help them understand the tiny birds.
Originally investigated for another reason, the strange exodus happened by chance during an ongoing study of the species' migratory patterns. Tiny, with an adult golden-winged warbler only weighing 9 grams, or the equivalent of 4 dimes, the researchers originally sought to investigate the birds' behavior with geolocators, which may indicate to researchers why current population sizes in the Appalachians have fallen to only 5 percent of their historic levels. But since the birds have revealed an extremely beneficial adaptation to foresee problems with nature, the study may have revealed anthropogenic causes for their decimation.
