Preserving wintering frugivorous birds in agro‐ecosystems under land use change: Lessons from intensive and super-intensive olive orchards

Fleshy-fruit production is becoming more intensive worldwide, but how this
affects frugivorous birds is poorly known. In the Mediterranean region,
intensive and super-intensive olive orchards are fast expanding,
potentially affecting millions of wintering songbirds. Here we test the
idea that intensification may benefit frugivorous birds, at least locally,
due to increased fruit availability, while negatively affecting the wider
wintering bird community due to intensive management, structural
simplification and landscape homogenisation. We estimated olive abundance
and surveyed birds in early, mid- and late winter, at traditional,
intensive, and super-intensive orchards in southern Portugal. We used
Hierarchical Modelling of Species Communities to relate species richness,
prevalence and abundance to management intensity, winter period, olive
availability and landscape context, and evaluated the role of frugivory on
observed responses. Olive availability was much higher throughout the
winter in more intensive than in traditional orchards, both in trees and
on the ground. Frugivorous bird abundance was higher in more intensive
orchards, and the most abundant frugivorous species (blackcap, song
thrush, robin) were positively affected by olive availability and/or
increasing landscape cover by olive orchards, while intensification level
had relatively minor effects after accounting for other variables.
Non-frugivorous richness and abundance were higher in traditional
orchards, and many non-frugivorous species were less prevalent in more
intensive orchards or negatively affected by landscapes dominated by olive
cultivation. Synthesis and applications. While negatively affecting the
wider bird community, our results suggest that olive farming
intensification can contribute to sustain large numbers of frugivorous
birds in the Mediterranean region. As frugivorous birds are not seen as
damaging by olive farmers, there is an opportunity to promote their
conservation in intensive and super-intensive orchards, which requires
management to increase habitat heterogeneity, and to reduce risks such as
mortality associated with mechanical harvest and contamination with
pesticide residues. Overall, we recommend that efforts to manage farmland
biodiversity should consider the impacts and conservation opportunities of
fruit crop intensification.