Sighting frequency decreases over two decades in three populations of Testudo hermanni from central Italy

摘要: Sighting frequency of tortoises (Testudo hermanni), standardized by the number person-hours field effort, was studied between 1992 and 2013 at three different study areas in central Italy. Although tortoise sightings fluctuated substantially across years among areas, there a significant declining trend all with GLM analyses showing also interaction area sampling year. The decreasing higher Castel Fusano than other two sites, yearly being independent search effort areas. These trends may indicate population declines, because no explanations seem plausible. Total rainfall from previous autumn to period positively correlated only one locality. juvenile did not vary significantly years, thus indicating that simple differences detectability cannot explain observed patterns. Summer fires forest overgrowing decline (Castel Oriolo) whereas we were able identify any specific reason for third (Manziana).