167 Lynx, n. s. (Praha), 41: 167–173 (2010). ISSN 0024-7774 (print), 1804-6460 (online) Influence of some methodological modifications on trapping efficiency and mortality of small terrestrial mammals (Rodentia) Vplyv niektorých metodických modifikácií na efektivitu odchytu a mortalitu drobných zemných cicavcov (Rodentia) Peter LEŠO & Rudolf KROPIL Department of Forest Protection and Wildlife Management, Technical University in Zvolen, Faculty of Forestry, T. G. Masaryka 20, SK–960 53 Zvolen, Slovakia; leso@vsld.tuzvo.sk, kropil@vsld.tuzvo.sk received on 15 June 2010 Abstract. Live trapping of small terrestrial mammals was carried out in a mature fir-beech forest. Influence of trap type, bait type and frequency of checks on trapping effectiveness and mortality was examined. Two dominant rodent species Apodemus flavicollis and Myodes glareolus were used as model animals. The mean effectiveness of the Chmela-type live traps reached 37.27%. On the contrary, the effectiveness of pitfalls was only 0.56%. An extremely low number of shrews was captured using both trap types. Trap- ping efficiency was similar for dry cat food and rolled oats, regardless of the rodent species. Apodemus flavicollis showed a significant difference in trapping frequency between day and night. The activity of Myodes glareolus was more even. Both species showed a higher mean number of individuals captured from sunset to midnight than from midnight to sunrise. Mortality of the model species was 5–17 times lower when carrying out four checks per day in comparison to the standard number of two checks. Key words. Live traps, pitfall traps, trapping efficiency, bait, time activity, mortality, Apodemus flavicollis, Myodes glareolus. INTRODUCTION The study of small mammal assemblages requires trapping data. The effort to obtain these data is complicated by differences in body size and microhabitat use among species, which can affect species- and trap-type-specific probabilities of captures (MCCAY et al. 1998, WHITTAKER & FEL- DHAMER 2000). Many studies have showed that different trap types show different effectiveness in capturing a particular species or group of species (WIENER & SMITH 1972, PELIKÁN et al. 1977, SLADE et al. 1993, WOODMAN et al. 1996, WHITTAKER et al. 1998, STANKO et al. 1999). The capture probability of different species may also be influenced by choice of the bait used for trapping (BEER 1964, LAURANCE 1992, WILLAN 1986, WOODMAN et al. 1996) and by the trapping design (PELIKÁN et al. 1975, ZUKAL & GAISLER 1992, MCCAY et al. 1998). In the present study, we tested two types of live traps, two types of bait and capability in different times of day. The influence of doubled trap checks was also discussed in relation to mortality and calculated density.