Index Line Catches as a Basis of Population Studies on Small Mammals

Abstract

The studies were carried out in southern Sweden and dealt with factors affecting index line catches and the ratio between index line catches and population density. There is a pronounced repellant effect from trapped sexually inactive animals in multiple catching traps when the catch approaches 1 animal per trap. During these conditions animals which become active soon after the traps are set will be over-represented. The catch is also influenced by the type of trap and bait used. In order to obtain unbiased samples there should be many single catching traps per trapping point. It was possible to transfer line values to population density by combined index line/removal captures. The relations between index line catch and population density were very different in the species Apodemus flavicollis, A. sylvaticus and Clethrionomys glareolus; the catch of the first one being proportionally greatest. There was no significant evidence of different trappability of the species during the year. Pe3loMe B RO)HOII MBeLgHH IIPOBOARHJI H3y1eHHe ycJIOBHIA, onpegeiisoimx OTJIOB rp]I3YHOB H COOTHouIeHSH Me)Kgy HIOTHOCTbhO HOnyHlyHA H HHHeKCOM OTYIOBa. EBInO yCTaHOBJIeHO, TO, ecJIH B JIOBYLIKY ,AJISI MHorOKpaTHrO OTJIOBa ioiagaeT OAHO )ICHBOTHoe, OHO OKa3bIBaeT onpege~ieHHoe OTiiyrHsaioinee BJ15IHHe Ha xgpyriae oco6H. B 3THX YCJIOBHsX WKHBoTHme, npoxogmsge B aKTHBHOe COCTOAHHe BCKope 0nocJie YCTaHOBKH JIOBymeK, iPieACTaBJIeHbI TaM B H36bITKe. OTJOB 3aBHCHT TaKxce OT THIIa JIOByLUeK H xapaKTepa npHMaHKH. B gen~ix noJIy'IeHHR HaH6ojiee o6seKTHBHBIX C6OPOB HeO6XOgHMO CTaBHTb 6oni0Z oe KOjI1H'eCTBO JIOBymeK giiA OAHHO'IHOrO OTROBa B KaxCgOrl H3 HCCJiegyeMbIX TO'eK. flpeACTaBji5eTC B03MO)KHBIM OnpegeJ'IHT]6 IIJIOTHOCTB HoryjiHLHH rpbI3yHOB HO KoM6HHHpOBaHHbIM gaHHBIM Be3IH'IHHbI OTJIOBa (OTCYTCTBHe B JIOBymnKax. COOTHOLLieHHI4 Mem)wy HHAexKCOM OTJIOBa H IIJIOTHOCTbIO HOIYJ15RIHH CHJRLHO pa3JIH'aIOTCS y BHAOB Apodemus flavicollis, A. sylvaticus R Clethrionomys glareolus. Y nepBoro H3 HHX 3TH BeJIH'HHbI HaH6oJree nporopLRHOHaJIbHbI. OnpegewieHHLIX gaHHbIX Ho Ce3OHHOtA 4HaMHKe OTJIOBa He nOjiyqeHO. Manuscript accepted April 1967. 18* OIKOS 18, 2 (1967) This content downloaded from 157.55.39.215 on Wed, 31 Aug 2016 04:34:29 UTC All use subject to http://about.jstor.org/terms