COMMON TOAD DECLINE NOT LINKED TO SURROUNDING LANDSCAPE

Amphibians are experiencing the steepest declines of any vertebrate group. Not only rare species are affected, also species considered widespread and resilient are in decline. In this study we investigated the extent of decline of Common Toad (Bufo bufo) populations in Flanders. Additionally, we examined whether population trends can be explained by the surrounding landscape, as first step to unravel causes of decline. 

Common toad, Bufo bufo (© Ellen Blomme)

We received data collected by volunteers of Natuurpunt Studie during toad patrol actions. These patrols are performed year after year, which creates a rare opportunity to quantify long-term population trends at a regional scale. Toad patrol actions were performed across Flanders, allowing us to estimate population trends for over 200 locations, confirming a widespread decline. These site-specific trend values were used to test associations with landscape characteristics (identity, structure and land use change) at different spatial scales.

Key findings

• In Flanders there is a substantial decline with nearly 39% of the populations decreasing, while only 10% showed an increase. Among the declining locations, 40% have reached densities so low that patrol efforts have been discontinued.

• Landscape characteristics do not explain decline:

  None of the landscape variables showed an association with the population trends. This suggests that the decline in Flanders is not primary driven by the surrounding landscape. Nevertheless, specific land use combinations or small landscape elements can still impact toad populations.

Future perspectives

Here we showed that landscape is not one of the primary drivers of decline. However, the decline of toad populations is probably driven by multiple interacting stressors. Other possible causes are contaminants, connectivity loss, invasive species, climate change, loss of genetic diversity and diseases.

Want to learn more?

You can read the full scientific study here. This research part of the OSSOBufo project, supported by the Special Research Fund of Ghent University (BOF23/GOA/008), investigating causes of decline of the Common Toad (Bufo bufo). If you want to learn more about this project, you can visit the project page on our website.