Decline and Extinction of the Italian Agile Frog Rana latastei from Core Areas of Its Range

SIMPLE SUMMARY: The Habitats Directive is the main legislative tool to protect European biodiversity and aims to ensure the persistence of species listed in its annexes. Here, we document the changes in abundance and occurrence of the Italian agile frog (Rana latastei) within Monza Park, which currently represents the area closest to the type locality of the species. We found that the range of the species inside the park strongly contracted in the early 2000s due to the destruction of breeding sites. Then, around 2021, the species completely disappeared from the area, probably due to the joint effects of inappropriate management and droughts. The extant legal protection did not prevent the local extinction of the Italian agile frog from a core area of its range; hence, we call for more effective tools for the conservation of European biodiversity. ABSTRACT: Detecting the trends of species and populations is fundamental to identifying taxa with high conservation priority. Unfortunately, long-term monitoring programs are challenging and often lacking. The Italian agile frog Rana latastei is endemic to Northern Italy and adjacent countries, is considered vulnerable by the IUCN, and is protected at the European level. However, quantitative estimates of its decline are extremely scarce. In this study, we document the trends in abundance and distribution of Rana latastei within Monza Park, which currently represents the area closer to the type locality of the species and holds unique genetic features. Wetlands within the park were monitored from 2000 to 2023; counts of egg clutches were taken as a measure of reproductive output and the abundance of breeding females. In 2000, the species occurred over a significant proportion of the park. Total abundance showed strong yearly variation but remained rather constant from 2000 to 2019. However, Rana latastei disappeared from the park around 2021 and was never detected in 2022–2023. The decline is probably related to the joint effect of multiple factors, including the conversion of breeding sites for farming, inappropriate water management, invasive alien species, and severe drought. The local extinction of Rana latastei occurred despite legal protection, highlighting the need for more effective and stringent tools for the conservation of European biodiversity.