Dr Klaus Riede, Global Register of Migratory Species www.groms.de.

As early as 1962, Rachel Carson observed the loss of birds by pesticides. She said this phenomenon was resulting in a "silent spring" — a time without bird songs. Our world is getting more and more silent with every species’ extinction, and today a new generation of pesticides is accumulating in the environment, which is having catastrophic effects on all insects, and will eventually affect birds as well. 
One way to monitor species and their survival is through the vocalizing of animals, known as “bioacoustic monitoring.” Here at the Congress, workshop on bioacoustics brought together experts from around the world working with birds, frogs and grasshoppers. These specialists confirmed that bioacoustic monitoring provides an excellent opportunity for automatised (hence cheaper!) monitoring. Even though this novel approach is limited to calling animals, it can provide valuable data on species in hard-to-access regions and nocturnal rainforests where species can be easily overlooked, but never overheard!

Bruce Beehler, an ornithologist working with Rapid Assessments at Conservation International, reminded participants that bioacoustics expert, the late Ted Parker, was ultimately able to recognize all South American birds by their song.

Through bioacoustic monitoring, soundscapes can be made accessible to experts via the internet, and can then help to identify species that are recorded in endangered habitats. Automatic classification remains a big challenge, however, particularly when analyzing complex multispecies recordings from rainforests. Axel Hochkirch, who is leading the IUCN Grasshopper Specialist Group points out that insects have highly stereotyped songs, which makes him optimistic that automatic grasshopper song classification will be available in the not-too-distant future.

I reported on autonomous recording stations already deployed by the EU-funded Life+project AmiBio in Greece. These stations have been generating terabytes of sound data since 2010. For example, in marine ecosystems, whales and dolphins are already being monitored by a wide network of hydrophones and regular surveys.

Participants came to the conclusion that better cooperation is needed when it comes to bioacoustic monitoring—bringing together the many fragmented monitoring initiatives that are already in place and determining common data exchange protocols. Common protocols could add value to the existing data sets because properly archived island or amphibian recordings could also be analyzed by insect specialists. Existing sound archives will also play a crucial role, providing validated reference recordings to be used by experts and IT programmers around the world.