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

International audienceThere 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. © 202

Conséquences des introductions d’espèces végétales sur les communautés d’invertébrés terrestres des îles subantarctiques

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Conséquences des introductions d’espèces végétales sur les communautés d’invertébrés terrestres des îles subantarctiques

National audienc

Responses of common buzzard (Buteo buteo) and Eurasian kestrel (Falco tinnunculus) to land use changes in agricultural landscapes of Western France

In front of land use changes, there has been a wide decline in biodiversity. In this study, we analysed the numerical response of two diurnal raptor species, the common buzzard and the Eurasian kestrel to different agricultural landscape contexts. We carried out a 3-year survey of the abundance of these two species in three agricultural landscape contexts that are known to form a gradient of land use intensity and hedgerow network fragmentation. We also considered the variation in prey abundance related to these land use changes. The two raptor species showed negative but differentiated response patterns to land use intensification and small mammal abundance. The abundance of the common buzzard decreased significantly with the reduction of hedgerows, woodlots and grasslands areas, as well as with the decrease in prey abundance at the landscape scale. The abundance of the Eurasian kestrel showed the same trend, but fall of abundance was less marked and not significant. This resulted in a reverse ratio of species density according to agricultural intensification and landscape openness. Specific feeding habits, nesting habitats and spatial partitioning in foraging areas could explain the difference in the numerical response observed for these two raptor species. Buzzards forage mainly on highly profitable prey areas and avoid highly fragmented woodland habitats for nesting. Kestrels seem less dependent on semi-natural habitats, are able to nest in more fragmented landscapes and are better adapted to exploit less abundant but more widespread small mammal prey species within the cultivated matrix. The study may help to evaluate carrying capacities of agricultural landscapes in accordance with ecological life traits of these two raptor specie

Conséquences des changements d'usage des terres en zone agricole sur l'architecture d'un réseau trophique prédateurs-proies (rapaces/petits mammifères)

International audienc

Conséquences des changements d'usage des terres en zone agricole sur l'architecture d'un réseau trophique prédateurs-proies (rapaces/petits mammifères)

International audienc