Common vole numbers in relation to the utilization of burrow systems

Abstract

Populatio n dynamic s of th e commo n vole Microtus arvalis (Pallas, 1779), change s in th e numbe r of burro w systems, an d their utilization wer e studie d in perennia l crops of differen t regions of Polan d in 1970—1979. A multi-yea r cycle in commo n vole numbers wa s found . In th e norther n region of Poland , maximu m pea k numbers reache d 350 individuals/ha , an d in th e souther n region mor e tha n 1000 individuals/ha . An increas e in commo n vol e numbers in the multi-yea r cycl e w a s positively correlate d wit h th e numbe r of burro w systems. Highest increase s in commo n vol e numbers wer e observe d in autumn , an d lowest in spring. Pe r unit increas e in th e numbe r of burro w systems, t h e rat e of growt h in commo n vol e numbe r increased in th e years of pea k numbers an d decreased in th e years of decline. Th e percentag e of occupie d burro w systems (colonies) an d the numbe r of individuals pe r burro w system increase d wit h growin g populatio n size, b u t a t a declining rate . Multi-yea r an d annua l change s in commo n vol e numbers wer e mor e affecte d by change s in th e numbe r of occupied burro w systems tha n by change s in th e numbe r of individuals p e r system. Onl y in th e periods of numbers decline, the y mostly de - pende d on change s in the density of colony members. Th e factors underlyin g difference s in mea n numbers of M. arvalis in differen t regions of Polan d ar e discussed.