Bats “see” their world through sound. So what do they do in the fog of noise created by humans? It appears some seek out quieter spots and change their calls. Scientists trying to decipher how bats cope with the racket of modernity went to natural gas fields in northern New Mexico. Some wells are equipped with compressors that create a constant din, while other wells are quieter. During 2 months of listening for the calls that bats use to locate prey, researchers found that Brazilian free-tailed bats spent 40% less time near compressors. These bats also altered their cries to a narrower acoustic range near the machinery. Bats with higher pitched calls more distinct from the compressors didn’t show changes. The study, published online this month in Global Ecology and Conservation, is the first to document bats in the wild changing behavior around human noise. It follows laboratory research that sounds of machinery hurt the performance of a bat species that hunts by listening for insects moving on the ground. The results raise the possibility that noise pollution is hurting some bats by depriving them of habitat or impairing hunting. Compressor noise in the study area covers 356 square kilometers of land where the free-tailed bats live, according to the study.
*Correction, 17 November, 11:12 a.m.: This item originally stated that compressor noise covers 356 square kilometers of land in places where the free-tailed bats live. The 356 square kilometers is actually the portion of the San Juan Basin (the location of the study) where the bats could be affected by compressor noise. The item has been corrected to reflect this.