Past and present existence of Spermophilus citellus in Hungary with a forecast of its population using time series models

The European ground squirrel (EGS) is an endangered burrowing rodent of Central and South-Eastern European dry grasslands with a declining population trend. Its prehistoric and historical distribution ranges and population trend have not been analysed until now. In this study we addressed these gaps and aimed to give a comprehensive view on the species history and forecast its population trend in light of past management actions. We collected data on the location and extinction of local colonies in Hungary from archaeological, geographical, and document archives and Hungarian monitoring databases. Statistical analysis focused on forecasting the trend and quantifying the change in the number of populations since 1964 by two-times interrupted autoregressive integrated moving average and Bayesian structural time-series models. Paleontological evidence indicated widespread distribution of the genus Spermophilus in Hungary in the last 1.45 million years. EGS has continuously inhabited this area for 2000 years. Documentary evidence supported that EGS inhabited 94 % of the area of Hungary if we assume a meta -population structure until the 2nd half of the XX th century. From 1964 EGS colonies showed a sharply declining trend until 2012. After 2012, the trend levelled out, however, the analysis could not exclude random fluctuations behind that positive change in the trend. The halt in decline may be attributed to the start of coordinated conservation reintroductions. Results indicated that translocations could provide a useful tool for species protection despite failures of translocations, though further data will be required to clearly accept or refute this metapopulation.