THÈSE - Université de Franche-Comté

SYNTHESIS AND IMPLICATIONS FOR CONTROL OF A. TERRESTRIS POPULATIONS
The present study demonstrated a bottom-up regulation of the dynamics of vole populations
on a parcel scale. It suggests a strong relationship between the growth and the abundance of A.
terrestris populations and their optimal habitat, whose characteristics can be modified by
certain farming practices and grassland management.
Our study showed that more intensive grassland management was favourable to A. terrestris
populations. This may be explained by the fact that grassland management may indirectly
favour T. europaea populations and provide better shelter against predators (Jacob & Brown
2000) and thermal variations (Jacob & Halle 2001). In contrast, practices like harrowing,
ploughing and grazing are unfavourable as they disturb soil burrows and vegetation cover.
However, as described by Jacob & Halle (2001), we found that each of these favourable and
unfavourable practices must be sufficiently intensive and repeated (frequent mowing and soil
work, intensive grazing) to have a long-term effect on vole populations.
However, we can not exclude that other variables could also affect the A. terrestris population
increase on a parcel scale. These variables could include soil and vegetation characteristics,
the landscape context and the farming management in adjacent areas. Indeed, theoretical
approaches have shown that dispersal alone conditional on the properties of local population
dynamics can explain density variations in lattice models (Ranta 1998). The role of predation
may also account for inter-annual variations of small mammal population density (Hanski et
al. 2001). Thus, on a larger scale, the role of arrangement of habitats and farming practices in
population dynamic control subsidiary or complementary to predation and parasitism (Newey
et al. 2005) cannot be discarded.
The interpretation of our results and their subsequent application in a control strategy will
have to consider (i) the phase of the population cycle (Edge et al. 1995), (ii) the spatial scale at
which control is to be carried out, (iii) the intensity and the duration of the disturbing farming
practices (Jacob 2003), (iv) the farming practice history in the area under study.
Chemical rodenticides currently used to prevent extensive crop damage are also hazards to
non-target animals and auxiliary fauna (foxes, buzzard, etc…) (Brakes & Smith 2005). They
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