Agricultural intensification heightens food safety risks posed by wild birds

1. 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. 2. 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 2024 faecal samples from
captured birds alongside 1215 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. 3. Campylobacter spp. were detected in 10.2% of faeces
from captured birds and 13.1% of faeces from production areas. Nonnative
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 1 sample across the >3200 tested. 4.
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. 5. We encountered
bird faeces on 3.3% of plants examined. Despite the impact on pathogen
prevalence, landscape context did not increase the number of plants with
bird faeces, although on-farm mammalian livestock density slightly did. 6.
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.”