Prairie dogs hate rush hour, a group of Colorado biologists reported recently in the journal Animal Behaviour. The researchers took a recording of heavy traffic along Interstate 25 (about 5,600 vehicles-per-hour), and played the audio back in the presence of prairie dogs. The automotive cacophony repeatedly alarmed foraging prairie dogs, indicating that the rodents don't habituate well to human-made noise.
From May to August 2013, Colorado State University ecologists monitored how praire dogs react to highway sounds. When they played an hour-long recording at remote burrows (nearly a mile away from the nearest road, with minimal human exposure), "the number of prairie dogs aboveground declined by 21 percent, the proportion of individuals foraging was reduced by 18 percent, vigilance [looking about for predators] increased by 48 percent, while social and resting behaviour was halved" the scientists write.
Over the three-month-long course of the study, the researchers played the recording 10 times. Despite hearing the freeway fracas repeatedly, the prairie dogs remained alarmed by the sounds, diving back underground or becoming more wary of potential threats. "The effects of noise might be more insidious than we may have realized," study author and Colorado State University behavioral ecologist Graeme Shannon tells Livescience.
Across the globe, animals are living in an increasingly loud world. Cardinals and other songbirds chirp differently during rush hour -- and when boats make the sea a noisy place, even fish are shouting (or at least purring louder) to be heard over the din.