EN
The reliability of the estimation of residency time of the bank vole Clethrionomys glareolus (Schreber, 1780) and the yellow-necked mouse Apodemus flavicollis (Melchior, 1834) in open populations was assessed by halving the 6-week intervals between trapping sessions. The status of "single-capture" individuals was identified to estimate the probability that they are native young rather than adult invaders. We found that the majority of "single-session" individuals constituted true transients that were present in the study plot for a short time only. They were young, immature rodents with a small body mass and a small number of captures. The probability that the "single-session" individuals stay on the plot for a longer time was 0.35 and 0.37 for voles and mice, respectively. These ostensible transients were trap-prone, fully-grown, mature adults, that revealed their presence on the plot already at the beginning of each trapping session. We found that "single-capture" individuals were mainly young, immature rodents that were not retrapped. The probability that the single-capture rodents are mature individuals, with a longer residency time, was 0.10 and 0.18 for voles and mice, respectively.