‘This is one of the things that people in our field sit and talk and dream about, “Wouldn’t it be cool if someone caught one of these birds someday?’’,’ says Amber Roth, a researcher at the Michigan Technological University.
Roth and her fellow researchers finally caught a golden-winged warbler in Nicaragua’s Reserva el Jaguar. As warblers go, this was an unusual bird. It had already been caught and tagged in Illinois at the start of its migration to the south. ‘It’s a needle in the haystack for sure, especially for this species,’ adds Roth.
‘I saw a lot of golden-wings come through in the spring, but I had never caught one in Illinois,’ says James Marshall from Rockford University. Marshall tagged the warbler in Stevenson Dells, a shrubby ‘forest island’ environment that the warblers share with grouse and woodcocks.
Roth, meanwhile, attached a geolocator to the warbler, which allows the bird’s migration pattern to be tracked. Each year the warbler flies from the Great Lakes in the US to Central America.
Geolocators attached to warblers in previous experiments have revealed the bird appears to have an ability to detect incoming storms. When warblers arrived at a breeding ground in Cumberland, Tennessee it was for a short stay – the birds left almost immediately, and travelled around 900 miles in five days to avoid storms that produced major tornadoes.
‘The most curious finding is that the birds left long before the storm arrived,’ says Henry Streby from the University of California, Berkeley. ‘At the same time that meteorologists on The Weather Channel were telling us this storm was headed in our direction, the birds were apparently already packing their bags and evacuating the area.’ The warblers left the area 24 hours before the storm hit.
‘Meteorologists and physicists have known for decades that tornadic storms make very strong infrasound that can travel thousands of kilometres,’ says Streby.
Birds with sensitive hearing on the same frequency as a storm have a clue that extreme weather is on the way. Warblers will even alter migration routes to avoid storms, which could increase their resilience to climate change.
‘Our observation suggests [that] birds aren’t just going to sit there and take it with regards to climate change, and maybe they will fare better than some have predicted,’ Streby says. ‘On the other hand, this behaviour presumably costs the birds some serious energy and time that hey should be spending on reproducing.’