Grasshoppers are having to change their song -- one of the iconic sounds of summer -- to make themselves heard above the noise of road traffic, ecologists have discovered. The study, published in the British Ecological Society's journal Functional Ecology, is the first to show that human-made noise affects natural insect populations. Animals use sound to communicate for many reasons, including marking out territory, warning of predators and finding mates, and although previous research shows birds, whales and even frogs change their calls in noisy environments, the impact of human-made noise on insects has been neglected until now. Ulrike Lampe and colleagues from the University of Bielefeld in Germany caught 188 male bow-winged grasshoppers, half from quiet locations and half from beside busy roads. The grasshoppers use their song to attract mates. The team then studied the differences in the two groups' songs in the laboratory. To encourage them to sing they exposed the males to a female grasshopper, and then recorded their courtship songs. Analysis of almost 1,000 recordings revealed grasshoppers living beside noisy roads produced different songs to those living in quieter locations. According to Lampe: "Bow-winged grasshoppers produce songs that include low and high frequency components. We found that grasshoppers from noisy habitats increase the volume of the lower-frequency part of their song, which makes sense since road noise can mask signals in this part of the frequency spectrum ." The team's findings are important because traffic noise could be upsetting the grasshopper's mating system . "Increased noise levels could affect grasshopper courtship in several ways. It could prevent females from hearing male courtship songs properly, prevent females from recognizing males of their own species, or _ females' ability to estimate how attractive a male is from his song," Lampe explains. Having discovered that human-made noise affects insect communication, the researchers now want to learn more about how... The author wrote the article to _ . A) introduce how grasshoppers make noises to attract mates. B) raise the awareness of protecting bow-winged grasshoppers. C) inform us of a recent discovery of ecological research. D) warn us that human-made noise has changed ecological system.
A:
C