Location: Foodborne Toxin Detection and Prevention Research
Project Number: 2030-42000-054-006-R
Project Type: Reimbursable Cooperative Agreement
Start Date: Jan 1, 2022
End Date: Dec 31, 2023
Birds introduce complex food-safety risks, as they carry multiple pathogens, are difficult to exclude from farms, and regularly defecate on crops. Yet very few wild bird species have been studied, and those that have form a minority of farm bird communities. Moreover, existing studies stop at examining pathogen prevalence in birds and do not holistically assess food-safety risk. For a species to pose a significant risk, it must carry pathogens, visit fields, defecate on crops, and produce feces that support pathogen survival. Here, we propose to first identify species that carry pathogenic E. coli, Salmonella, and Campylobacter by coupling existing studies with assays of field-collected feces. Second, we will survey birds and collect feces on 15-20 farms near rangeland, natural habitats, or other farms to determine which species enter farms and defecate on crops and in which contexts. Third, we will compare E. coli survival between feces placed on different substrates (crops, organic/conventional soils, plastic mulch) and between feces from different species. Finally, we will compile holistic risk assessments for >50 species into a photographic guide to help growers identify and manage birds. Ultimately, we hope to help growers implement practices that bolster beneficial species without compromising food safety.
We will produce holistic food-safety risk assessments for wild birds on produce farms in California. We have already assembled a database of ~10,000 pathogen tests across ~100 bird species (i.e., Campylobacter spp., Shiga-toxin producing E. coli, and Salmonella spp. assays). First, we will capture wild birds on or near farms, collect their feces, and test them for each pathogen, prioritizing birds that are poorly represented in our database, especially those that use nest boxes. Second, we will quantify how proximity to rangeland affects bird abundance on farms and identify species most likely to defecate on crops. Specifically, across 15-20 farms, we will census birds, collect feces, and use DNA barcoding to identify which species produced ~1000 fecal samples. Third, we will conduct laboratory and field experiments to estimate E. coli survival curves in bird feces from different species, placed on lettuce, organic/conventional soils, or plastic mulches. Finally, we will combine our data on pathogen prevalence, defecation rates, and pathogen survival to develop risk assessments for common farmland bird species.