Scientists are to deploy a network of microphones in the Amazon rainforest to listen and measure the numbers and species of birds, insects and other wildlife.

The use of ‘ecoacoustics’ forms part of RAINFAUNA - a £1 million study by an international team of researchers led by scientists at Lancaster University that will provide the first large-scale understanding of how humans are affecting the animals that call tropical forests home.

Tropical forests are under threat. In the Amazon, at least 17% of primary forest has been affected by human disturbance, such as logging, fires and deforestation. Climate change and deforestation has increased regional temperatures by 2.5°C and dry season rainfall has plummeted by a third.

Much of our understanding of how tropical forests are degraded by these threats has come from studying trees, through surveying plots and using remote sensing technologies. However, less is known about how these changes are affecting tropical forest animals. This is despite tropical forests being the most diverse terrestrial ecosystems, and home to more than 60% of vertebrate species.

“Tropical forests are facing a perfect storm from changes in how land is used, other human disturbances and climate change,” said Professor Jos Barlow, Principal Investigator of RAINFAUNA from Lancaster University. “Despite this, we currently lack a good understanding of how these large threats are affecting the animals living within tropical forests across wide areas.”

While scientists can use satellite or airborne cameras and sensors to monitor trees across large areas, this does not work for animals within the forests and hidden by the canopy. However, advances in technology and new techniques mean assessing fauna at scale could finally be possible.

“RAINFAUNA will help resolve this huge gap in our knowledge by providing the first large-scale understanding of how climate change and forest disturbance determine the density, biomass and population sizes of tropical forest animals,” said Professor Barlow. “By adding in this key component of biodiversity, with their key roles in the forest ecosystems, not only will we have a greater understanding of how these animals are affected, we will also be able to use this knowledge to protect them for future generations.”

Funded by the Natural Environment Research Council (NERC), the team brings together experts from Lancaster University, Manchester Metropolitan University and the University of Exeter in the UK; the Federal University of Amazonas, the Brazilian Agricultural Research Corporation (Embrapa), and the National Center for Monitoring and Early Warning of Natural Disasters (CEMADEN) in Brazil; and the National Museum of Natural History in France.

The team aim to deploy a network of microphones across areas of the Amazon rainforest. Using novel modelling techniques that take into account variation in climate and vegetation, the researchers will measure the number of different species of birds in the understorey.

The research team will also install microphones in the forest soil to measure the density of insects and other invertebrates. This will provide insights into the important functions they carry out in the forests, such as decomposing material and the mixing of soil layers.

Dr Oliver Metcalf, who is an expert in ecoacoustics at Manchester Metropolitan University, said: “With the use of ecoacoustics, and novel modelling, enabling us to gather valuable data across large areas of forest we will for the first time be able to provide evidence-based estimates of contemporary, and future, densities of these bird and insect species. This will produce results that will be invaluable for both scientific discoveries but also for the management of these precious rainforests.”

Another key aspect of the research will focus on examining the relationship between microclimate and animals within the forest. The researchers believe that microclimate has the potential to be a key indicator of the health of a forest and provide insights into the densities of species within tropical forests.

“There is growing evidence that microclimate within tropical forests is key to understanding fauna as this is the climate experienced by the animals themselves and it is well established that it changes enormously in disturbed forests,” said Dr Ilya Maclean of the University of Exeter. “With our work in RAINFAUNA we aim to develop the first large-scale models to help realise the potential of microclimate as a predictor of tropical forest biodiversity.”

Dr Joice Ferreira of Embrapa, said: “By improving our understanding of rainforest fauna, this work will provide information vital for improving conservation policies across the Amazon.”