Check 1, 2, 3…

microphone2 iStock 000009679000XSmall Check 1, 2, 3...Listen closely and you might hear the sound of new acoustic technologies remaking field biology. A growing number of biologists are turning to sophisticated microphone arrays and signal-processing software to remotely eavesdrop on animals and ecosystems, concludes a new review. But land-based “bioacoustics” studies could become even more valuable if researchers move to share and harmonize techniques, the authors argue.

Nature lovers have been recording the sounds made by everything from birds to crickets for more than a century. As early as 1889, for example, Ludwig Koch — a German-born BBC broadcaster known as one of the fathers of wildlife sound – was recording bird song in his backyard. Today, the computer and electronics revolutions have produced sound-recording gear that is “transforming the way we study individuals and populations of animals, and are leading to significant advances in our understandings of the complex interactions between animals and their habitats,” a multinational team of researchers writes in the Journal of Applied Ecology.

Using arrays that can include dozens of microphones, for instance, researchers have been able to closely track tiny birds through nearly impenetrable tropical undergrowth and map out their territories. And specialized sound-analysis software can even help researchers figure out the species, age, and sex of noisy animals. Acoustic arrays have also enabled scientists to figure out when birds, such as sage grouse and blackbirds, are calling in a particular direction, or when they are sending broader signals. Understanding such “directional vocalizations” can be key to understanding behavior and adopting workable conservation strategies. Clever acoustic surveys also “provide insight into habitat quality and ecosystem health,” the authors note. Researchers have used recordings of grasshoppers, for instance, to assess the health of Bavarian grasslands.

“The wide-scale application of acoustic recording and processing technology has the potential to transform the fields of ecology, behaviour and conservation biology,” the team writes. But it will take a little innovation – and some sharing — to make the most of the new tools, they add. One “pressing challenge” is developing better signal-processing algorithms; another is developing common technologies that researchers can share – as opposed to the “customized” systems now in use.

To hurdle these obstacles, the authors suggest scientists “set up a website or wiki to serve as a repository for collective experiences and knowledge” – or expand an existing resource, such as the Bioacoustics listserv (www.mail-archive.com/bioacoustics-l@cornell.edu/maillist.html). Overall, however, they believe “the future for bioacoustic monitoring in the terrestrial environment is bright.” – David Malakoff | April 14, 2011

Source: Blumstein, D., Mennill, D., Clemins, P., Girod, L., Yao, K., Patricelli, G., Deppe, J., Krakauer, A., Clark, C., Cortopassi, K., Hanser, S., McCowan, B., Ali, A., & Kirschel, A. (2011). Acoustic monitoring in terrestrial environments using microphone arrays: applications, technological considerations and prospectus. Journal of Applied Ecology DOI: 10.1111/j.1365-2664.2011.01993.x

Image © Valerie Loiseleux

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