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

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.

Persistence of Seed Dispersal in Agroecosystems: Effects of Landscape Modification and Intensive Soil Management Practices in Avian Frugivores, Frugivory and Seed Deposition in Olive Croplands

“…In an increasing number of cases, this maintenance of herbaceous cover is combined with organic farming, but the area dedicated to organic olive growing is still a minority in the region. Modern hedge-like plantations, although rapidly proliferating are still marginal in the region, and convey a new and different facet of the intensification of olive production that is not considered in the present study (see Morgado et al, 2021, for the effects of superintensive olive farming in avian frugivore abundance and richness). Olive trees in all the localities were more than 30-years old and were grown with a plantation frame of 7 × 8 m or frequently higher.…”

“…The increasing area occupied by olive grove-dominated landscapes not only threatens frugivorous/insectivorous bird communities, it also lessens their functional complementarity and diminishes the connectivity, and potential regeneration of, the persisting remnant patches of seminatural woodland habitat within these landscapes. There is a current expansion of olive groves, toward superintensive olive growing in hedges, which could further aggravate the ongoing loss of frugivore diversity and frugivory in olive groves (but see Morgado et al, 2021) due to the deep structural modification of this agroforest-like agroecosystem. These threats could be generalized to most olive growing areas of the Mediterranean Basin since land conversion to olive cultivation by intensive and superintensive practices is being pursued throughout the entire region.…”

“…Olive cropland has expanded at the expense of Mediterranean native forest, woodlands, and scrublands (seminatural woodland habitats, SNWH hereafter), particularly rich in fleshy-fruited plant species (Herrera, 1984a;Jordano, 1984) and where avian seed dispersal by birds represents a major driver of woody vegetation recovery and the long-term dynamics of ecological communities Alcántara, 2000, 2014;Perea et al, 2021). However, unlike some notable information on avian frugivore abundance and diversity (Rey, 1993(Rey, , 1995(Rey, , 2011Morgado et al, 2021), data on frugivory and seed dispersal in olive grove landscapes is anecdotal, restricted to fruit consumption during winter by the most abundant frugivores, or taken from a single or a small number of localities (Jordano and Herrera, 1981;Rey, 1992;Blanco et al, 1994;Rey and Valera, 1999;Delibes et al, 2012;Perea and Gutiérrez-Galán, 2016).…”

“…This form of intensification has raised environmental concerns, especially from the recent advent of the superintensive hedge-like plantations, because it involves important structural changes and increased input demand that affects biodiversity and sustainability. Moreover, the accelerated expansion of hedge-type plantations demands new agricultural lands and the transformation of other (typically annual) croplands and/or traditional olive groves of old trees into this novel form of plantation (Moreira et al, 2019;Morgado et al, 2020Morgado et al, , 2021. Olive tree density based intensification is unevenly distributed in the Mediterranean region, with the traditional density frames still representing the vast majority in major olive producer countries, such as Spain, Tunisia, Italy, Greece, and Morocco (Vilar and Pereira, 2018).…”

Unmasking the perching effect of the pioneer Mediterranean dwarf palm Chamaerops humilis L.

“…humilis in the late-successional plot could be related to some of them producing fleshy fruits (e.g. Rubus ulmifolius , Asparagus aphyllus ), acting thus as an additional attractant for frugivorous birds [ 77 – 79 ]. Richness of beneficiaries was also found positively related to the number of seeds found on C .…”