Land use changes and raptor population trends: A twelve-year monitoring of two common species in agricultural landscapes of Western France

Abstract

There are serious concerns about the ecological degradation caused by modern agriculture and its impact on top-chains predators. But, scientists still disagree on how to assess which are the winners and losers of Anthropocene biodiversity changes.In this field of research, many studies have been carried out on passerine birds but long-term ones, and especially on raptors, are still missing. Our study reports a twelve-year survey on two diurnal common raptors (the Buzzard, Buteo buteo and the Eurasian kestrel, Falco tinnunculus) facing recent land use changes in Western France farmland landscapes. Precise remote sensing data were analyzed each year, allowing us to precisely describe land use changes and stability along this time series.Buzzards showed reduced abundances in intensified landscapes and responded negatively to wood habitat instability while kestrels were more abundant and stable when areas of meadows increased. According to life history traits of these two-raptor species, we may suppose that buzzards, as generalist predators, mainly suffer of nesting site decrease while kestrels suffer of food depletion and namely voles living in meadows.No decreasing or increasing regional or local trends was observed for buzzards during these 12-years confirming that populations seem adjust their numbers to fit to local resources. Inversely, kestrels exhibit significant population collapses at both regional and local scales.If limiting wood habitats fragmentation or disturbance would optimize buzzard densities, drastic management measures improving surfaces and quality of grassland habitats will be necessary to reverse the decline of the Eurasian kestrel, highlighted by this study.

Keywords

• Raptor
• Long term survey
• Trends
• Landscape dynamics
• Ecological indicators