Camera trap data suggest uneven predation risk across vegetation types in a mixed farmland landscape

Ground-nesting farmland birds such as the grey partridge (Perdix perdix)
have been rapidly declining due to a combination of habitat loss, food
shortage and predation. Predator activity is the least understood factor,
especially its modulation by landscape composition and complexity. An
important question is whether agri-environment schemes such as flower
strips are potentially useful for reducing predation risk, e.g., from red
fox (Vulpes vulpes). We employed 120 camera traps for two summers in an
agricultural landscape in Central Germany to record predator activity
(i.e., the number of predator captures) as a proxy for predation risk and
used generalized linear mixed models (GLMMs) to investigate how the
surrounding landscape affects predator activity in different vegetation
types (flower strips, hedges, field margins, winter cereal and rapeseed
fields). Additionally, we used 48 cameras to study the distribution of
predator captures within flower strips. Vegetation type was the most
important factor determining the number of predator captures and captures
rates in flower strips were lower than in hedges or field margins. Red fox
capture rates were the highest of all predators in every vegetation type,
confirming their importance as a predator for ground-nesting birds. The
number of fox captures increased with woodland area and decreased with
structural richness and distance to settlements. In flower strips, capture
rates in the centre were approximately 9 times lower than at the edge. We
conclude that the optimal landscape for ground-nesting farmland birds
seems to be open farmland with broad extensive vegetation elements and a
high structural richness. Broad flower blocks provide valuable,
comparatively safe nesting habitats and the predation risk can further be
minimized by placing them away from woods and settlements. Our results
suggest that adequate landscape management may reduce predation
pressure.