Abstract
Abstract 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 in modulating 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 had lower prevalence in more intensive orchards or were 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 sustaining 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.
Highlights
Fleshy fruit crops represent an abundant food source that can contribute to sustain frugivorous birds in agricultural landscapes (Rey, 2011), which can result in conflicts with farmers (Lindell, 2020)
While negatively affecting the wider bird community, our results suggest that olive farming intensification can contribute to sustaining large numbers of frugivorous birds in the Mediterranean region
We tested the following hypothesis: (a) The availability of ripe olives is higher in more intensive olive orchards, though it may decline rapidly due to high harvest efficiency; (b) olive abundance and landscape coverage by olive orchards positively affect the richness and abundance of frugivorous species; and (c) structural simplification in more intensive orchards and landscape coverage by olive farming negatively affects overall species richness and abundances, that of non-frugivorous species
Summary
Fleshy fruit crops (e.g. grapes, olives, berries) represent an abundant food source that can contribute to sustain frugivorous birds in agricultural landscapes (Rey, 2011), which can result in conflicts with farmers (Lindell, 2020). Like other fruit crops (Rime et al, 2020), olive cultivation has fast intensified during the past decades (Sánchez-Martínez & Paniza Cabrera, 2015; Tous et al, 2010), but little is known about how this affects wintering birds Gaining such understanding is important to inform bird conservation and management in intensive fruit crops. Intensification may bring benefits through increased olive availability in highly productive orchards (Muñoz- Cobo & Montesino, 2003; Rey et al, 1996), though consequences may be negative, for non-frugivorous species, due to structural orchard simplification (Costa et al, 2020; Morgado et al, 2020) and landscape homogenisation reducing the availability of alternative habitats (Santana et al, 2017). We tested the following hypothesis: (a) The availability of ripe olives is higher in more intensive olive orchards, though it may decline rapidly due to high harvest efficiency; (b) olive abundance and landscape coverage by olive orchards positively affect the richness and abundance of frugivorous species; and (c) structural simplification in more intensive orchards and landscape coverage by olive farming negatively affects overall species richness and abundances, that of non-frugivorous species
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