Trophic relationships of the common vole in cultivated fields

3100 ha, 2 winters, I summer. estimates of vole numbers incr by 25% to allow for non-trappables. Microtus 1-300/ha in fields, forest rodents 7-43/ha. Weasels estimated from 26 captures in 30 straps over 150 ha = 328 ha/weasel, probably underestimated especially as weasels in stacks not counted. 100 weasel scats analysed – ate a third of body weight (90 g) per day. When voles low all predators together accounted for 79% of total mortality, but when high only 11%. Key predator was fox, then cats, then weasels. Less pressure on forest rodents when Microtus high. Relative functional response clear. Ecological efficiency weasels 0.56%, accounted for 18% of individual Microtus. Concludes predators unable to prevent an outbreak.

Author L. Ryszkowski, J. Goszczynski and J. Truszkowski
Year 1973
Secondary title Acta Theriologica
Volume 18
Number 7
Pages 125-165