Spadefoot Toad Populations Show Conservation Paradox in the Netherlands
A flourishing population of the common spadefoot toad (Pelobates fuscus) has been discovered in the coastal dunes of the Netherlands, presenting a conservation paradox. This comes as the species has experienced a rapid decline in its natural habitat in the south and east of the country. The discovery, detailed in research published in February 2023 in Amphibia-Reptilia, has prompted scientists to investigate the origins of this introduced population.
Researchers are utilizing mitochondrial DNA (mtDNA) barcoding to determine the provenance of the spadefoot toads found in the dunes. The study, originally documented on February 22, 2023, aims to understand how this introduced population came to thrive while the native populations struggle.
Road Mitigation Efforts and Toad Mortality
Elsewhere in the Netherlands, efforts are underway to mitigate the impact of roads on common toad (Bufo bufo) populations. A study conducted by researchers at Wageningen Environmental Research examined the effectiveness of amphibian tunnels and drift fences in reducing road mortality. The research, published in February 2019, involved a capture-mark-recapture study to evaluate the performance of these mitigation measures.
The study found that only 31% of marked common toads utilized the tunnels to cross the road. Researchers assessed several factors that might explain this low usage rate, including the distance between the toads’ initial capture location and the nearest tunnel, the distance traveled along the fences, the number of toads moving in the wrong direction after encountering the fences, and the time elapsed between the first and last capture of each toad group.
Despite the mitigation measures, 28% of migrating toads – both marked and unmarked – still ended up on the road surface. The installation of the tunnels and fences led to an approximate 75% decrease in migrating population numbers.
Biodiversity Awareness on University Campuses
On , World Biodiversity Day 2024 marked the beginning of a series of activities at the University of Twente campus focused on raising awareness about biodiversity. One article in this series highlighted the migration patterns of the common toad (Bufo bufo). Volunteers have been instrumental in expanding the scope of these biodiversity initiatives.
The University of Twente’s efforts reflect a broader concern for amphibian conservation in the Netherlands, as both spadefoot toads and common toads face challenges from habitat loss, road mortality, and potentially other environmental factors. The contrasting situations – a declining native spadefoot toad population alongside a thriving introduced one – underscore the complexities of conservation efforts and the need for continued research to understand the dynamics of these populations.
Further research is needed to fully understand the long-term implications of the introduced spadefoot toad population and to optimize road mitigation strategies for common toads and other amphibian species in the Netherlands.
