This year’s amphibian rescue season has come to an end. Due to the weather conditions, the season was unusually long; we conducted rescue operations on 40 evenings, with an average of 6 volunteers participating each night. Warm and rainy days in February and March drew amphibians out, but because the nights remained cold, most amphibians migrated only during the early part of the night. As a result, migration was gradual, and we rescued an average of 150 amphibians per evening. On the busiest night, we rescued as many as 582 amphibians. This spring was therefore very different from last year, when on the peak night we rescued 1,829 amphibians.
Such gradual migration requires much more effort from the rescue teams, and this year the volunteers contributed a total of 500 hours of their free time. Their perseverance paid off, as we rescued 7,232 amphibians, including 5,761 common toads, 657 green frogs, 567 common toad, 153 brown frogs, and 6 green tree frogs. Despite all our efforts, we still recorded 3,109 road-killed amphibians, and many more were likely overlooked, as carcasses quickly disappear from the road. Overall, we rescued about 70% of the amphibians we observed.
At the start of the season, the goal of rescuing 10,000 amphibians proved too ambitious, but our campaign was nonetheless very successful. In other parts of Slovenia, the number of rescued amphibians was up to 90% lower than last year, whereas at Lake Cerknica we experienced only a 15% decrease. Fluctuations in population numbers are a natural occurrence and can result from various factors affecting juvenile development, such as droughts in 2021 and 2022. In wetter years, like 2023, amphibians can reproduce more successfully, though the effects may be observed with a delay of several years.
Because of these fluctuations, it is crucial to rescue amphibians during their spring migration. Road mortality has such a significant impact that only 20% or fewer of migrating amphibians manage to cross safely without assistance. This means that without intervention, population numbers tend to spiral downward over time, leading toward local extinction — with serious negative consequences for both the ecosystem and humans.
It is therefore important to provide amphibians and other wildlife with the safest possible passage across roads. In the meantime, we can assist them through volunteer rescue actions. We would like to sincerely thank all the volunteers who participated in this year’s campaign, especially Veronika, Slavica, and Helena. Thank you to Maruša and Radio 94 for radio support, and to donor Eva for helping us purchase the first 100 meters of fencing. Thanks also to the Herpetological Society, which lent an additional 200 meters of amphibian fencing. We are grateful to the Slovenian Infrastructure Directorate for providing extra traffic signs, and to Notranjska Park, the Municipality of Cerknica, and the landowners where the fences were installed for their support. Finally, we thank all drivers for their patience on the roads.
Article prepared by Rudi Kraševec, biologist at Notranjska Park and a volunteer with the Guardians of Amphibians Lake Cerknica "Cuprnške Žabe".
