US scientists say tracking data showing five golden-winged warblers left their nesting site a day before a tornado outbreak suggests they "heard it coming". Geolocators showed the birds, left the Appalachians and flew 700km (400 miles) south to the Gulf of Mexico. The next day the deadly April 2014 tornadoes swept across the central US. The Current Biology report suggests birds may sense and escape extreme events in this way. Dr Henry Streby, from the University of California, Berkeley, said he initially set out to see if tracking the warblers was even possible. "This was just a pilot season for a larger study that we're about to start," Dr Streby told the BBC. "These are very tiny songbirds - they weigh about nine grams. "The fact that they came back with the geolocators was supposed to be the great success of this season. Then this happened!" The birds had just completed a 5,000km migration, when they made this extra trip. Everybody out Working with colleagues from the Universities of Tennessee and Minnesota, Dr Streby tagged 20 golden-winged warblers in May 2013, in the Cumberland Mountains of north-eastern Tennessee. The birds are often seen around the Great Lakes and the Appalachian Mountains, where they nest and breed every summer. After disappearing to Colombia for the winter, 10 of the tagged warblers returned in April 2014. The team was in the field observing them when they received advance warning of the tornadoes. "We evacuated ourselves to the waffle house in Caryville, Tennessee, for the one day that the storm was really bad," Dr Streby said. Elsewhere in the US the storm had more drastic consequences. At least 84 tornadoes caused 35 fatalities and more than $1bn (£0.6bn) in property damage. After the storm had blown over, the team recaptured five of the warblers and removed the geolocators. These are tiny devices weighing about half a gram, which measure light levels. Based on the timing and length of the days they record, these gadgets allow scientists to calculate and track the approximate location of migratory birds. In this case, all five indicated that the birds had taken unprecedented evasive action, beginning one to two days ahead of the storm's arrival. "The warblers in our study flew at least 1,500km (932 miles) in total," Dr Streby said. They escaped just south of the tornadoes' path - and then went straight home again. By 2 May, all five were back in their nesting area. Jump media playerMedia player helpOut of media player. Press enter to return or tab to continue. Aerial footage, captured by a drone in the wake of the storms, shows emergency vehicles and debris on a highway in Arkansas Remarkably, the warblers' evacuation commenced while the closest tornado was still hundreds of miles away. Weather conditions in the nesting area were still nothing out of the ordinary. via BBC News.