Agricultural intensification heightens food safety risks posed by wild birds

Abstract

Abstract Agricultural intensification and simplification are key drivers of recent declines in wild bird populations, heightening the need to better balance conservation with food production. This is hindered, however, by perceptions that birds threaten food safety. While birds are known reservoirs of foodborne pathogens, there remains uncertainty about the links between landscape context, farming practices, and actual crop contamination by birds. Here, we examine relationships between landscape context, farming practices, and pathogen contamination by birds using a barrier‐to‐spillover approach. First, we censused bird communities using point count surveys. Second, we collected 2,024 faecal samples from captured birds alongside 1,215 faecal samples from brassica fields and food processing areas across 50 farms spanning the USA West Coast. We then estimated the prevalence of three foodborne pathogens across landscape and livestock intensification gradients. Finally, we quantified the number of plants with faeces. Campylobacter spp. were detected in 10.2% of faeces from captured birds and 13.1% of faeces from production areas. Non‐native birds were 4.1 times more likely to have Campylobacter spp. than native birds. Salmonella spp. were detected in 0.2% of faeces from production areas and were never detected in captured birds. We detected evidence of Shiga toxigenic E. coli in one sample across the >3,200 tested. Campylobacter spp. prevalence in faeces from production areas increased with increasing mammalian livestock densities in the landscape but decreased with increasing amounts of natural habitat. We encountered bird faeces on 3.3% of plants examined. Despite the impact on pathogen prevalence, amount of natural habitat in the landscape did not increase the number of plants with bird faeces, although on‐farm mammalian livestock density slightly did. Synthesis and applications. Food safety and wildlife conservation are often thought to be in conflict. However, our findings suggest that natural habitat around farms may reduce crop contamination rates by birds. This is perhaps because natural habitat can promote native birds that are less likely to harbour foodborne pathogens or because it decreases contact with livestock waste. Our results suggest that preservation of natural habitats around farms could benefit both conservation and food safety, contrary to current standards for ‘best practices’.