Grazing pressure on grass meadows by red deer

Grazing by wildlife on agricultural land is widespread across geographical
regions, and can cause human-wildlife conflicts due to reduced crop yield
when the grazing pressure is high. Growing red deer (Cervus elaphus)
populations in Europe calls for an increased understanding of their
grazing patterns to mitigate damages. We quantified how red deer grazing
pressure (grazing presence and grazing level) on agricultural grass
meadows (n = 60) in Norway varied across multiple spatial scales. We used
a nested, hierarchical study design transcending from broad scale (meadows
across the landscape) to intermediate (between nearby meadows) and local
(within-meadow) scale, allowing us to identify at which scale the
variation in grazing pressure was strongest. We estimated how grazing was
determined by broad-scale factors influencing forage availability and
quality through population density, distance to coastline and differences
between the first versus second harvest, by intermediate-scale factors in
terms of meadow management causing differences in botanical composition
and quality, and by local-scale factors in terms of perceived predation
risk and disturbance. At broad scale, higher population densities were
associated with higher grazing pressure, and more grazing occurred before
the first compared to the second harvest. Intermediate-scale factors
explained the most variation of grazing pressure from red deer, with
higher grazing pressure on newly renewed meadows compared to other nearby
meadows. On local scale, more grazing occurred closer to the forest edge,
providing cover, and further away from infrastructure, with increased risk
and disturbance. Overall, our study highlights how drivers of grazing
pressure on agricultural land vary across spatial scales. Population
reductions on broader scale may have some effect in reducing the grazing
pressure, but renewed meadows will nevertheless attract red deer causing
higher grazing pressure compared to neighbouring meadows. This insight is
crucial for determining effective mitigation strategies facing rising red
deer populations across Europe.