Effects of agriculture development on vole dynamics and conservation of Montagu's harrier in western French wetlands

摘要: Abstract Nesting populations of Montagu's harrier (Circus pygargus) are declining in most parts Europe; France, western marshes remain the important nesting sites terms breeding pairs. In this open field landscape dominated by grasslands, common vole (Microtus arvalis) displays regular population outbreaks and constitutes a favourite prey raptor. Twelve years data indicate significant variations size young harriers produced, which correlate with yearly differences densities. Up to 10 ago, these were traditionally used as extensive pastures but recent agricultural changes have resulted almost 50% being converted drained production, already observed many localities region next our study area. Our data, together previous collected from 1968 region, demonstrate that decrease frequency intensity peaks. A summer density 100 voles/ha appears threshold value support good success harriers. These modifications fluctuation pattern suggest French could be endangered future under current trends changes.