Bird predation affects diurnal and nocturnal web-building spiders in a Mediterranean citrus grove

Mestre, Laia; García, Núria Fernández; Barrientos, J. A.; Espadaler, Xavier; Piñol, Josep

doi:10.1016/j.actao.2013.01.001

Cited by 14 publications

(10 citation statements)

References 28 publications

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“…; Maas, Clough & Tscharntke ; Mestre et al . ). Overall, increases in most predatory arthropods and decreases in individual herbivores due to bird exclusion suggest mesopredator release and may at least partly explain the ambivalent effects of birds on cacao yield in our study, although food web data will be necessary to confirm this.…”

Section: Discussionmentioning

confidence: 97%

“…The exact mechanism is unclear, as the fogging data show only a trend towards increases in predator densities at canopy cover below 30% for ants and small web spiders with increases and decreases at canopy cover above 50% for larger web spiders and earwigs, respectively. Generally, increased abundances of predators, such as ants, spiders and earwigs, under bird exclusions, are common (Gunnarsson 2007;Williams-Guill en, Perfecto & Vandermeer 2008;Piñol et al 2010;Maas, Clough & Tscharntke 2013;Mestre et al 2013a). Overall, increases in most predatory arthropods and decreases in individual herbivores due to bird exclusion suggest mesopredator release and may at least partly explain the ambivalent effects of birds on cacao yield in our study, although food web data will be necessary to confirm this.…”

Section: A N O P Y C O V E R -D E P E N D E N T E F F E C T S O F Amentioning

confidence: 99%

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How ants, birds and bats affect crop yield along shade gradients in tropical cacao agroforestry

Gras

Tscharntke

Maas

et al. 2016

Journal of Applied Ecology

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1. Tropical agroforests are diverse systems where several predator groups shape animal communities and plant-arthropod interactions. Ants, birds and bats in particular can reduce herbivore numbers and thereby increase crop yield. However, the relative importance of these groups, whether they interact, and how this interaction is affected by management and landscape context, is poorly understood. 2. We jointly manipulated access of ants, birds and bats in Indonesian smallholder cacao agroforestry across gradients of shade and distance to natural forest. We quantified arthropod abundance, pest damage and yield. 3. In control treatments, yield was highest under 30-40% canopy cover. Ant exclusion strongly reduced yield (from 600 to 300 kg ha À1 year À1 ) at 15% canopy cover. Bird exclusion impaired yield (from 400 to 250 kg ha À1 year À1 ) at 60% and enhanced yield (from 600 to 900 kg ha À1 year À1 ) at 15% canopy cover, while bats had no effect. Yield increased with forest proximity, a pattern not related to predator access. 4. No interactive effects among predator exclusions on yield, pest damage and arthropod communities were found. Ant exclusion increased numbers of herbivores below 30% canopy cover, without reducing spider abundances. Bird exclusion reduced herbivore and increased spider abundances. 5. Synthesis and applications. Using exclusion studies, we estimated that ants and birds cause cacao yield to vary between 100 and 800 kg ha À1 year À1 , depending on shade-tree management. In all but the most shaded agroforests, ants were pivotal in supporting yields. Yields under low-canopy cover were strongly dependent on access by predator groups, with birds reducing rather than increasing yield. Hence, cacao farmers should refrain from disturbing ant communities and maintain 30-40% shade-tree canopy cover not only for ecophysiological reasons but also to buffer variability in predator communities.

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Section: Discussionmentioning

confidence: 97%

Section: A N O P Y C O V E R -D E P E N D E N T E F F E C T S O F Amentioning

confidence: 99%

How ants, birds and bats affect crop yield along shade gradients in tropical cacao agroforestry

Gras

Tscharntke

Maas

et al. 2016

Journal of Applied Ecology

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“…Given the importance of herbivorous arthropod suppression for plant communities, including crops, further research into the factors underlying spatial and phylogenetic variation in bird and bat predation is encouraged. Moreover, birds and bats also frequently limit numbers of arthropod predators such as ants and spiders (Van Bael et al., ; Mooney et al., ; Mestre et al., ; Karp & Daily, ; but see e.g. Hooks et al., ; Borkhataria et al., ; Maas et al., ; Michel et al., ; Fig.…”

Section: Effects On Food Websmentioning

confidence: 99%

Bird and bat predation services in tropical forests and agroforestry landscapes

et al. 2015

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Understanding distribution patterns and multitrophic interactions is critical for managing bat‐ and bird‐mediated ecosystem services such as the suppression of pest and non‐pest arthropods. Despite the ecological and economic importance of bats and birds in tropical forests, agroforestry systems, and agricultural systems mixed with natural forest, a systematic review of their impact is still missing. A growing number of bird and bat exclosure experiments has improved our knowledge allowing new conclusions regarding their roles in food webs and associated ecosystem services. Here, we review the distribution patterns of insectivorous birds and bats, their local and landscape drivers, and their effects on trophic cascades in tropical ecosystems. We report that for birds but not bats community composition and relative importance of functional groups changes conspicuously from forests to habitats including both agricultural areas and forests, here termed ‘forest‐agri’ habitats, with reduced representation of insectivores in the latter. In contrast to previous theory regarding trophic cascade strength, we find that birds and bats reduce the density and biomass of arthropods in the tropics with effect sizes similar to those in temperate and boreal communities. The relative importance of birds versus bats in regulating pest abundances varies with season, geography and management. Birds and bats may even suppress tropical arthropod outbreaks, although positive effects on plant growth are not always reported. As both bats and birds are major agents of pest suppression, a better understanding of the local and landscape factors driving the variability of their impact is needed.

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“…The main predators of spiders are birds [28,58]. Gunnarsson's (1998) field experiment clearly showed that spiders were considerably more abundant on branches protected against birds compared to control branches exposed to bird predation [31].…”

Section: Discussionmentioning

confidence: 99%

Impact of Habitat Complexity on Body Size of Two Spider Species, Alopecosa cuneata and A. pulverulenta (Araneae, Lycosidae), in River Valley Grasslands

Stańska¹,

Stański²,

Wielgosz³

et al. 2018

Pol. J. Environ. Stud.

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Many studies have shown that vegetation structure and habitat complexity affect taxonomic composition, functional diversity, and the number of individuals in spider assemblages. These factors also affect spider body size, but mechanisms responsible for that are still not well understood. In our research, we examined the relationship between the body size of spiders from two species -Alopecosa cuneata and A. pulverulenta -and environmental factors such as habitat type and habitat complexity. Our research was conducted in the Bug River Valley on 12 plots covering three types of habitats: mesic meadow, sandy grassland, and xerothermic grassland. Spiders were collected in 2007-08 from April to mid-November using pitfall traps. In total we measured 334 males and 168 females of Alopecosa cuneata and 315 males and 104 females of A. pulverulenta. The generalized linear mixed model revealed that individuals of Alopecosa cuneata as well as A. pulverulenta reached larger sizes in more complex vegetation, whereas the habitat type did not affect the spider body size. One of the likely mechanisms responsible for a larger body size in more complex habitats is predator pressure. Birds as the main predators of spiders, being selective in their choice of prey, may collect larger spiders with higher intensity than smaller ones. We suggest that more complex habitats with dense vegetation provide better shelter for large spiders, which allows them to avoid predators. Our results indicate that habitat complexity may be an important determinant of body size distribution in spider assemblages.

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Bird predation affects diurnal and nocturnal web-building spiders in a Mediterranean citrus grove

Cited by 14 publications

References 28 publications

How ants, birds and bats affect crop yield along shade gradients in tropical cacao agroforestry

How ants, birds and bats affect crop yield along shade gradients in tropical cacao agroforestry

Bird and bat predation services in tropical forests and agroforestry landscapes

Impact of Habitat Complexity on Body Size of Two Spider Species, Alopecosa cuneata and A. pulverulenta (Araneae, Lycosidae), in River Valley Grasslands

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