Romans are using artificial bird calls to put an end to this beautiful starling murmuration above the Eternal City. Every winter, the skies over Italy's capital are filled with the mesmerising sight of thousands of starlings swooping and diving in unison. But when they stop to rest on treetops, their droppings coat pavements and cars below - prompting the city authorities to scare them away. "We act on their fear by using their own alarm call," says Marianna Di Santo, a member of the Fauna Urbis task force. Clad head-to-toe in white protective clothing, she waves a speaker emitting a series of sharp cries, emulating the natural alarm call of the birds. As she heads towards Roma Termini central train station, thousands of birds shoot up from their roosting spots and spiral into the sky. Between October and February every year, millions of starlings migrate from northern Europe to Italy in search of warmer temperatures for the winter. Their synchronised ballets - or murmurations, as they are more commonly known - send twisting shadows over the Eternal City's churches, palaces and ruins. "I've never seen such a thing in my life. It's spectacular," says Eva Osuna, a Spanish tourist taking out her phone to capture the magic. The glossy dark-feathered birds, which measure up to 20 centimetres in length, spend their days feeding in rural areas before heading back into town to sleep. "In the city, the temperatures are higher and the light helps them find their way around and protects them from predators," explains ornithologist Francesca Manzia. Warmer temperatures in northern Europe caused by climate change have shortened the starlings' stay in Italy, but their sheer numbers make them a force to be reckoned with. Over one million are believed to be in Rome this year, according to experts. Naturally "gregarious", they stick together at night, creating collective dormitories in the trees. "They do not carry disease," insists Manzia. "But because of their droppings, they make the roads slippery and smell very strong."

Even on a clear day, it is not uncommon to see Romans walking along tree-lined streets with umbrellas as protection against the birds. City authorities use sounds and lights to divide the animals into smaller, more manageable groups. Audio transmissions are "the most simple and effective" way of moving the birds on, says Valentina de Tommaso from Fauna Urbis. She works two or three times a week near Termini, which with its wide roof offers “a comfortable place for the birds to rest." "We play recordings for about ten minutes, with breaks in between so they do not get used to the noise," she says. The piercing noise draws a small crowd - some of them approving, others less so. "They pose lots of problems. Walking around under flocks of starlings is not really ideal," says Francesco Fusco, a 55-year-old engineer. "But if the city is a reference point for these birds because it is a stop on their migration route, then they have the right to stop here!"