In order to protect hibernating bats effectively, more knowledge about mortality factors is needed. This study proved the wood mouse (Apodemus sylvaticus) actively predates on bats. Fresh remains made by the wood mouse can be identified due to a typical pattern of lesions. This study was conducted in the province of Zuid-Holland, between the cities of Den Haag (The Hague), Leiden and the town of Wassenaar (between 52-070 and 52-090N, 4-180 and 4-210E). During a preliminary investigation with a trail camera, we were able to prove that wood mice actively searched for prey. Thereafter, remains of partially eaten bats have been collected and inspected in the laboratory. Bats which had not died of predation were excluded from the analysis. The remains that we found showed the typical pattern of lesions attributable to predation by wood mice. The skin of the victims is scraped clean. In the process of eating all the soft tissue, the skin is turned inside out, including the skin around the skull and hind legs. We found a total of 214 remains of predated bats during the 12 years. The resulting data are presented in this dataset. Files Distance to entrance Status: status of observation, this is a filter for fresh remains. Date: date of the observation of the remains. Note: observations were made each 2 weeks, not necessarily the date of death. Species: fresh remains of what bat species Location: name of hibernacula, location of observation N of animals: number of fresh remains Distance: distance to the exit (in meters) Oak and predation Winter: the period between September and April is defined as the winter of the year starting in January Predation: N of fresh remains found in one winter Cumulative N of bats: The cumulative population, based on the maximum population size of each site. Mast production of the common oak (kg): kg of acorns. We used annual data on the seed production of common oak collected by the ‘Vereniging Wildbeheer Veluwe’ in the province of Gelderland as a measure for the availability of acorns in our study area. Predation and winter population Winter: the period between September and April is defined as the winter of the year starting in January Predation: the Number of predated bats Max N: the maximum population size Location: the hibernacula

{"references": ["Haarsma, A. J., & R. Kaal (2016). Predation of wood mice (Apodemus sylvaticus) on hibernating bats. Population Ecology, 1-10."]}