OCCUPANCY OF AVIAN FORAGING GUILDS IN SOYBEAN FIELDS AND BORDERS IN ENTRE RÍOS, ARGENTINA: RESPONSES TO VEGETATION STRUCTURE AND PREY RESOURCES

ANDREA GOIJMAN; MICHAEL J.CONROY; VANINA VARNI; JEFFREY J. THOMPSON; MARÍA ELENA ZACCAGNINI

Avian Research

BMC

Año: 2020 vol. 11

2053-7166

Bird conservation, and associated ecosystem services, is challenged by agricultural intensification and expansion. In Pampas grassland and Espinal forest ecoregions of east-central Argentina these processes have been ongoing and rapid, requiring the assessment of their impact on biodiversity so as to recommend management alternatives. The objective of this study was to gather evidence to inform decision-making for bird conservation in agroecosystems, focusing on foraging guilds and potential ecosystem services provided. I evaluated the effects of land use on birds at a regional scale in the Pampas and Espinal, using 10 years of a regional bird monitoring program, modeling occupancy with hierarchical multi-species dynamic models using a Bayesian approach. At a local scale, I evaluated factors influencing the use of soybean fields and borders by birds, using bird surveys and arthropod sampling in 78 borders and 20 soybean fields, in four crop stages for two years. I analyzed bird occupancy using multiple-groups single-season models, separating field interior and edges, and fitting Poisson mixed models for counts of the orders of arthropods consumed by birds. I used structured decision making (SDM) to find optimal management strategies to integrate bird conservation with soybean agriculture. I demonstrated how the regional scale results can be used as a tool for decision-making, mapping species-based spatial distributions over time. Although potential ecosystem services offered by birds were distributed throughout the study area, few species could provide them in crop dominated areas. Most raptors, unlike other guilds, were associated with soybean. Most insectivore gleaners seemed unaffected by crops, suggesting their perception of landscape at smaller scales. Birds in soybean fields are mainly those common in agroecosystems, some likely providing pest control service, while most guilds benefited from native trees in borders. Counts of arthropods preyed by birds remained mostly constant throughout the soybean cycle. Finally, I identified the objectives of the SDM process: maximizing insectivorous birds and farmers? well-being, while minimizing management costs. Reducing insecticide applications in soybean, and either planting trees in borders or no management, were the best decisions dependent on constraints of cost allocation and percent of managed border.