As the global biodiversity crisis worsens, it is increasingly important to obtain reliable data on the occurrence, distribution and habitats of different species. Many areas of high conservation value remain understudied because of limited resources, their vast size, and the difficulty and time required to survey elusive or rare species using traditional methods. Passive acoustic monitoring (PAM) could offer an effective solution. A new paper, based on acoustic data collected through the ELSP-supported Polesia project, reveals how this technology can improve our understanding and protection of biodiversity across large landscapes.
The potential of passive acoustic monitoring
The potential of PAM for large-scale biodiversity surveys is widely recognised. However, it is rarely used in conservation practice because of limited knowledge about how to collect and analyse these types of data. Technologies for automatically processing PAM data have also only recently begun to emerge.
Despite its impressive potential, the authors of the new paper point out that few studies have used PAM to collect data on multiple taxonomic groups, and that no published studies have used PAM data to prioritise conservation efforts at the landscape scale.
Revealing Polesia’s hidden biodiversity
The acoustic survey in Polesia was the first of its kind in the region and an important step in studying this landscape of exceptional conservation value. Although the network of protected areas here is extensive, many gaps remain.
In Polesia, the designation of protected areas is usually based on data covering a limited range of well-studied species. At the same time, the region’s ‘hidden’ biodiversity includes many species that are much harder to find and study. These species are numerous and play an important role in maintaining the balance of the region’s ecosystems.
For the first time in Polesia, this survey collected valuable data on the distribution and activity of cryptic, nocturnal and poorly studied species, including bats, small mammals and stridulating bush crickets. These species are often neglected in biodiversity monitoring because of the time and labour required to survey them.
The data help to answer two important questions: does the existing network of protected areas adequately safeguard these populations, and where should future efforts to protect the Polesian wilderness be focused?
The multi-taxa approach used in the study is vital because many of these understudied species are threatened by human activities and the fragmentation of natural areas, yet are seldom considered when conservation strategies are developed.
Recording wildlife across the landscape
During the acoustic survey conducted in 2019–2022, sound recorders were deployed at 506 sampling points across the Ukrainian and Belarusian part of Polesia. In total, the survey produced 2,884 nights of data, equivalent to 34,000 monitoring hours.
Using a combination of machine learning and subsequent manual verification, the team identified 644,543 vocalisations from 15 bat species, 6,130 vocalisations from six species or groups of small mammals, 17,153 stridulations from 17 bush cricket species, and 99,902 vocalisations from 13 species of nocturnal birds.
The researchers then used statistical models to create detailed maps predicting the distribution and activity levels of these species across the entire 151,000 km² study area. The authors also analysed how the distribution of these animals overlaps with the existing network of protected areas and highlighted the territories that could be most important for conservation. These include areas supporting a high diversity of species or serving as critical strongholds for animals threatened with extinction globally or within Europe.
Assessing the protected area network
When mapping the distribution of the target taxonomic groups, the researchers took the locations of nationally protected areas and Emerald Network sites into account. They analysed the overlap between strongholds for the surveyed species and areas with protected status.
Their analysis confirmed the value of nationally protected areas. Existing national parks and nature reserves in Polesia support a greater variety of birds and bats, as well as higher levels of acoustic activity, used as a proxy for abundance, for most of these species than comparable unprotected land.
This suggests that the current protected area network, originally designed to safeguard better-known species, is already providing important, previously undocumented benefits for the region’s lesser-known wildlife. The findings provide further evidence of the value of legal protection and the practical conservation measures that accompany it.
Identifying gaps in protection
However, the study also revealed a critical finding: between two-thirds and nearly 90% of the biodiversity hotspots identified are located outside the current protected area network. This represents a significant gap. According to the research, an estimated 14,000 to 16,000 additional square kilometres of land would require targeted conservation measures for each animal group.
The maps created during the study can help identify and prioritise new areas for protection, especially those that serve as key habitats for multiple species. The PAM data indicate that Emerald Network sites are associated with high concentrations of bats and small mammals and high levels of acoustic activity.
Unfortunately, these sites currently lack legal protection and practical conservation measures in Ukraine. This study provides evidence to support future advocacy focused on safeguarding these sites and the species they support, which in turn provide food for predators and contribute to the wider ecosystem.
An efficient tool for conservation
The authors of the study emphasise that PAM is highly efficient in terms of the resources required and the quantity and value of the scientific data obtained. Despite Polesia’s challenging terrain and limited road access, each fieldworker can deploy five to ten acoustic recorders in a single day.
Unlike traditional research methods, this work does not necessarily require species-specific knowledge and can be carried out by volunteers or non-experts. More than 500 sites can be surveyed in fewer than 200 days of fieldwork, including the deployment and collection of recording devices.
At the same time, PAM provides a relatively straightforward way to collect data on multiple taxonomic groups simultaneously, including rare, cryptic and nocturnal species that are typically understudied. It enables researchers to rapidly map the distributions of multiple species across extensive and understudied landscapes.
These data can support site-based conservation, long-term population monitoring, phenological studies and the assessment of restoration efforts. Combining PAM with traditional research methods can produce particularly valuable results. These opportunities are important for conservation practice not only in Polesia, but around the world.
This article was originally published on the Polesia website. Read the full study here.
