Damage to silo bags by mammals in agroecosystems: a contribution for mitigating human-wildlife conflicts

Abstract

Context: Damage to harvest storage systems by mammals and associated postharvest losses generate human-wildlife conflicts. Silo bags have been widely adopted worldwide as a type of temporary harvest storage for agricultural crops. The basis of silo-bag technology is the hermetic condition of the plastic lining. Breaks in this silo-bag lining by mammals generate damage of stored content and are a serious concern for farmers, who generally take actions against wildlife with consequent impacts on the environment. Aims: We described the incidence and intensity of breaks in silo-bag linings by different mammal groups (armadillos, canids and rodents) in agroecosystems of central Argentina, and we analysed the influence of extrinsic and intrinsic factors on patterns of breakage of silo bags, and propose management options based on cultural methods tending to prevent damage and reduce human-wildlife conflicts. Methods: Sampling was conducted during the austral summer and winter of 2018, at three sites in the Pampas of Argentina. At each site, we chose farms that were using at least one silo bag, described silo-bag characteristics, and recorded the number of breaks in silo bags generated by mammals. Key results: We sampled a total of 306 silo bags from 38 farms. Damage incidence by mammals comprised 49% of silo bags sampled. Statistical analyses (GLMMs) revealed that damage intensity generally increased with storage time. Seasonality played a key role, with breakage being higher during summer for armadillos, when they are most active, and in winter for rodents, when they are most abundant. Damage by armadillos exhibited geographic variation and also decreased significantly with increasing distance to the nearest plot edge in which the silo bag was placed. Damage by rodents was higher for bags containing grains rather than forage. Conclusions: Damage to silo bags by mammals was affected by both extrinsic (seasonal and geographical) and intrinsic (stored content, storage time and distance to nearest edge) factors; however, these effects varied according to the mammal group considered. Implications: Relocation of silo bags away from plot edges could significantly reduce damage by armadillos, the most harmful mammals to silo bags.