2015, Peisley, Rebecca K, Saunders, Manu, Luck, Gary W

Wild fauna occur in every agroecosystem and their interactions with crops can influence yields positively or negatively. Research on the impact of fauna activity on agricultural production focuses mostly on either the costs (e.g. crop damage) or benefits (e.g. pollination) of this activity, with few studies addressing cost-benefit trade-offs in the same context. This has resulted in an incomplete understanding of the implications of fauna activity in agroecosystems. Through a systematic review of the literature, we connect disparate studies to promote a more holistic approach to research on wild fauna in agriculture. We identified 281 studies that quantified a cost and/or benefit of fauna activity in crop systems. Overall, 53.0 % of studies examined the costs of insect and/or bird activity, 37.7 % of studies examined benefits and just 9.3 % of studies covered both costs and benefits of insect and/or bird activity simultaneously. Most birds studied were omnivorous (44.8 %), granivorous (29.0 %) or insectivorous (16.6 %), while insect studies focused on pollinators (42.2 %) or borers (17.5 %). There were clear geographic patterns for studies, with a bias towards studies of the costs of bird activity in North America and studies of benefits in Central America/Caribbean. Most studies on benefits occurred in perennial crops and most cost studies in annual crops. Our results highlight the disjointed nature of research into the cost–benefit trade-offs of fauna activity, and it is essential that future studies examine these trade-offs in order to develop sustainable agricultural strategies that limit production losses while maximising the delivery of ecosystem services from fauna.

2017, Peisley, Rebecca K, Saunders, Manu, Luck, Gary W

Context: Birds active in vineyards in south-eastern Australia can reduce or enhance crop yields via their foraging activities (e.g. by consuming grapes or by preying on grape-eating species). Aims: We examined the effectiveness of artificial perches in encouraging predatory birds into vineyards to scare frugivorous birds and consequently reduce the damage they cause to grapes. Methods: We monitored 12 artificial perches for 4 months during the growing season, spread over six vineyards in north-eastern Victoria, and compared bird damage to grapes at these sites with control sites without perches. Key results: We found that raptors did not use the artificial perches. However, the large and aggressive Australian magpie (Cracticus tibicen) commonly used perches and we recorded 38 513 perch visits by this species. Grapevines around perch sites suffered >50% less grape damage (4.13% damage per bunch) than control sites (8.57% damage per bunch). Conclusions: Our results suggest that providing artificial perches in vineyards can play a role in reducing frugivore damage to grapes. However, the effectiveness of perches can vary under different environmental conditions and certain perch types are not suitable for all predatory or aggressive birds. Implications: Future research should focus on the potential role of large-bodied and competitively aggressive species such as the Australian magpie in altering the activity of smaller frugivorous birds in vineyards, and also on the optimum height and location of artificial perches within vineyards to increase visitation by other predatory or aggressive bird species.

2016, Saunders, Manu, Peisley, Rebecca K, Rader, Romina, Luck, Gary W

Ecological interactions between crops and wild animals frequently result in increases or declines in crop yield. Yet, positive and negative interactions have mostly been treated independently, owing partly to disciplinary silos in ecological and agricultural sciences. We advocate a new integrated research paradigm that explicitly recognizes cost-benefit trade-offs among animal activities and acknowledges that these activities occur within social-ecological contexts. Support for this paradigm is presented in an evidence-based conceptual model structured around five evidence statements highlighting emerging trends applicable to sustainable agriculture. The full range of benefits and costs associated with animal activities in agroecosystems cannot be quantified by focusing on single species groups, crops, or systems. Management of productive agroecosystems should sustain cycles of ecological interactions between crops and wild animals, not isolate these cycles from the system. Advancing this paradigm will therefore require integrated studies that determine net returns of animal activity in agroecosystems.

2016, Peisley, Rebecca K, Saunders, Manu, Luck, Gary W

Birds active in apple orchards in south-eastern Australia can contribute positively (e.g., control crop pests) or negatively (e.g., crop damage) to crop yields. Our study is the first to identify net outcomes of these activities, using six apple orchards, varying in management intensity, in south-eastern Australia as a study system. We also conducted a predation experiment using real and artificial codling moth (Cydia pomonella) larvae (a major pest in apple crops). We found that: (1) excluding birds from branches of apple trees resulted in an average of 12.8% more apples damaged by insects; (2) bird damage to apples was low (1.9% of apples); and (3) when trading off the potential benefits (biological control) with costs (bird damage to apples), birds provided an overall net benefit to orchard growers. We found that predation of real codling moth larvae was higher than for plasticine larvae, suggesting that plasticine prey models are not useful for inferring actual predation levels. Our study shows how complex ecological interactions between birds and invertebrates affect crop yield in apples, and provides practical strategies for improving the sustainability of orchard systems.

2017, Peisley, Rebecca K, Saunders, Manu, Robinson, Wayne A, Luck, Gary W

Scavenging birds can provide ecosystem services to pastoralists by contributing to the breakdown of animal carcasses that can harbour and spread disease. However, these benefits have yet to be quantified in Australia. We monitored rabbit carcasses using motion-sensor cameras to identify beneficial avian scavengers across four landscape types (forest, riparian, fields with large isolated trees, and open fields) on a pastoral property in north-central Victoria. We quantified the ecosystem service of carcass breakdown by measuring the per cent weight loss of carcasses exposed to scavenging birds compared to carcasses excluded from birds. Seven of the twenty-four bird-accessible carcasses were attacked by raptors in 2014, and three in 2015. When a raptor attacked a carcass, there was a significantly higher median per cent weight loss of the carcass (16.67%, interquartile range (IQR) = 8.33-100.0) compared with sites where no bird attacks occurred (6.65%, IQR = 3.03-12.06). Our results indicate that raptors are major contributors to carcass breakdown in grazing landscapes and may potentially contribute to reducing the spread of diseases such as blowfly strike and leptospirosis. Maintaining key habitat features for these species (e.g. large isolated trees) is essential for raptor conservation and maximising the ecosystem services they provide.