As human impacts on the world accelerate, so does the need for tools to monitor the effects we have on species and ecosystems. Alongside technologies like camera traps and satellite remote sensing, passive acoustic monitoring (PAM) has emerged as an increasingly valuable and flexible tool in ecology. The idea behind PAM is straightforward: autonomous acoustic sensors are placed in the field to collect audio recordings. The wildlife sounds within those recordings are then used to calculate important ecological metrics – such as species occupancy and relative abundance, behaviour and phenology, or community richness and diversity.
The Pros and Cons of Passive Acoustic Monitoring
Using sound to monitor ecosystems, rather than traditional survey methods or visual media, has many advantages. For example, it’s much easier to survey vocalising animals that are nocturnal, underwater or otherwise difficult to see. Also, because acoustic sensors capture the entire soundscape, it’s possible to calculate acoustic biodiversity metrics that aim to describe the entire vocalising animal community, as well as abiotic elements in the environment.
The use of PAM in ecology has been steadily growing for a couple of decades, mainly in bat and cetacean studies. But with sensor costs dropping and audio processing tools improving, there’s currently a massive growth in interest in applying acoustic methods to large-scale or long-term monitoring projects. As very low-cost sensors such as AudioMoth start to emerge, it’s becoming easier to deploy large numbers of sensors in the field and start collecting data. Continue reading →
Bush-crickets are a little-known group of insects that inhabit our marshes, grasslands, woods, parks and gardens. Some may be seen in the summer when they are attracted to artificial lights, but as most produce noises that are on the edge of human hearing, we know little about their status. There are suggestions that some bush-crickets may be benefiting from climate change, while others may be affected by habitat changes. But how to survey something that is difficult to see and almost impossible to hear? Continue reading →
– ctmm: An R package which implements all of the continuous-time stochastic processes currently in use in the ecological literature and couples them with powerful statistical methods for autocorrelated data adapted from geostatistics and signal processing.
The biggest library of bat sounds has been compiled to detect bats in Mexico – a country which harbours many of the Earth’s species and has one of the highest rates of species extinction and habitat loss.