The large-scale field experiment on the interaction between the least weasel (Mustela nivalis nivalis) and its main prey species, the field vole (Microtus agrestis), continued during 1999. In nature, the numbers of weasels follow the numbers of voles with a time lag. In this experiment we have released captive-born least weasels in order to eliminate this time lag in the weasels numerical response. Altogether 120 weasels have been released in different study areas since 1996. The study sites are three large islands (5-10 km2) in big lakes in southern and central Finland. On these experimental islands and on adjacent control islands the dynamics of voles have been monitored by live trapping and by a small quadrat method. The experiment also involves avian predator and small game censuses. The captive breeding program of least weasels has been continued in the facilities provided by the Lammi Biological Station. Altogether 44 litters have been born since the program started in 1 996. 16 litters were born in 1999. Unfortunately, the mortality was highest in this year due to high temperatures and heavy flea infestation during the critical period for young weasels. This project is funded by the Academy of Finland (a grant to I. Hanski, H.Henttonen and H. Lindén).
Vastaava tutkija
Hanski Ilkka, Lammin biologinen asema, Lammin biologinen asema Hankkeen kesto 1998 -
Asiasanat
populaatioekologia, peto-saalissuhde, myyrä
Hankkeen vaihe: päättynyt
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