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Recent foodborne illness outbreaks have heightened pressures on growers to deter wildlife from farms, jeopardizing conservation efforts. However, it remains unclear which species, particularly birds, pose the greatest risk to food safety. Using11,000 pathogen tests and 1565 bird surveys covering 139 bird species from across the western United States, we examined the importance of 11 traits in mediating wild bird risk to food safety. We tested whether traits associated with pathogen exposure (e.g., habitat associations, movement, and foraging strategy) and pace-of-life (clutch size and generation length) mediated foodborne pathogen prevalence and proclivities to enter farm fields and defecate on crops. Campylobacter spp. were the most prevalent enteric pathogen (8.0%), while Salmonella and Shiga-toxin producing Escherichia coli (STEC) were rare (0.46% and 0.22% prevalence, respectively). We found that several traits related to pathogen exposure predicted pathogen prevalence. Specifically, Campylobacter and STEC-associated virulence genes were more often detected in species associated with cattle feedlots and bird feeders, respectively. Campylobacter was also more prevalent in species that consumed plants and had longer generation lengths. We found that species associated with feedlots were more likely to enter fields and defecate on crops. Our results indicated that canopy-foraging insectivores were less likely to deposit foodborne pathogens on crops, suggesting growers may be able to promote pest-eating birds and birds of conservation concern (e.g., via nest boxes) without necessarily compromising food safety. As such, promoting insectivorous birds may represent a win-win-win for bird conservation, crop production, and food safety. Collectively, our results suggest that separating crop production from livestock farming may be the best way to lower food safety risks from birds. More broadly, our trait-based framework suggests a path forward for co-managing wildlife conservation and food safety risks in farmlands by providing a strategy for holistically evaluating the food safety risks of wild animals, including under-studied species.

Farmland diversification practices (i.e., methods used to produce food sustainably by enhancing biodiversity in cropping systems) are sometimes considered beneficial to both agriculture and biodiversity, but most studies of these practices rely on species richness, diversity, or abundance as a proxy for habitat quality. Biodiversity assessments may miss early clues that populations are imperiled when species presence does not imply persistence. Physiological stress indicators may help identify low-quality habitats before population declines occur. We explored how avian stress indicators respond to on-farm management practices and surrounding seminatural area (1-km radius) across 21 California strawberry farms. We examined whether commonly used biodiversity metrics correlate with stress responses in wild birds. We used ∼1000 blood and feather samples and body mass and wing chord measurements, mostly from passerines, to test the effects of diversification practices on four physiological stress indicators: heterophil to lymphocyte ratios (H:L), body condition, hematocrit values, and feather growth rates of individual birds. We then tested the relationship between physiological stress indicators and species richness, abundance, occurrence, and diversity derived from 285 bird point count surveys. After accounting for other biological drivers, landscape context mediated the effect of local farm management on H:L and body condition. Local diversification practices were associated with reduced individual stress in intensive agricultural landscapes but increased it in landscapes surrounded by relatively more seminatural area. Feathers grew more slowly in landscapes dominated by strawberry production, suggesting that nutritional condition was lower here than in landscapes with more crop types and seminatural areas. We found scant evidence that species richness, abundance, occurrence, or diversity metrics were correlated with the individual's physiological stress, suggesting that reliance on these metrics may obscure the impacts of management on species persistence. Our findings underscore the importance of considering landscape context when designing local management strategies to promote wildlife conservation.Algunas veces se considera a las prácticas de diversificación agrícola (es decir, los métodos usados para producir alimentos de manera sustentable mediante el enriquecimiento de la biodiversidad en los sistemas de cultivo) como benéficas para la agricultura y la biodiversidad, pero la mayoría de los estudios sobre estas prácticas dependen de la riqueza, abundancia o diversidad de especies como indicadores de la calidad del hábitat. Las valoraciones de la biodiversidad pueden ignorar las señales tempranas de una población en peligro cuando la presencia de la especie no implica persistencia. Los indicadores de estrés fisiológico pueden auxiliar en la identificación de hábitats de baja calidad antes de que ocurra la declinación poblacional. Analizamos las respuestas de los indicadores de estrés en aves al manejo en las granjas y áreas seminaturales circundantes (1 km de radio) de 21 cultivos de fresas en California. Evaluamos si las medidas comunes de biodiversidad se correlacionan con las respuestas al estrés de las aves silvestres. Usamos aproximadamente mil muestras de sangre y plumas y medidas de masa corporal y cuerda alar, la mayoría de paseriformes, para analizar los efectos de las prácticas de diversificación sobre cuatro indicadores de estrés fisiológico: la relación heterófilos/linfocitos (H:L), condición corporal; valores hematocritos; y la tasa de crecimiento de las plumas en aves individuales. Después probamos la relación entre los indicadores de estrés fisiológicos y la riqueza, abundancia, presencia y diversidad de especies tomadas de 285 conteos por puntos de aves. Después de considerar otros factores biológicos, el contexto del paisaje medió el efecto de la gestión de las granjas locales sobre la H:L y la condición corporal. Las prácticas locales de diversificación estuvieron asociadas con una reducción en el estrés individual en los paisajes con agricultura intensiva; sin embargo, el estrés aumentó en los paisajes rodeados por áreas relativamente más seminaturales. Encontramos poca evidencia que respalde que las medidas de riqueza, abundancia, presencia y diversidad de especies estuvieran correlacionadas con el estrés fisiológico de los individuos, lo que sugiere que depender de estas medidas puede nublar el impacto de la gestión sobre la persistencia de las especies. Nuestros descubrimientos apuntalan lo importante que es considerar el contexto del paisaje cuando se diseñan las estrategias de gestión local para promover la conservación de la fauna.农田多样化实践(即通过提高耕作系统的生物多样性来可持续生产的方法)有时被认为有益于农业和生物多样性, 但对这些实践的研究大多依赖于物种丰富度、多样性或丰度作为栖息地质量的评估指标。当物种的出现并不意味着持续存在时, 生物多样性评估可能会错过种群受到威胁的早期线索。生理压力指标可能有助于在种群数量下降前识别低质量的栖息地。本研究探讨了 21 个加州草莓农场中鸟类压力指标对农场管理和周围半自然区域 (半径 1 公里) 的响应。我们研究了常用的生物多样性指标是否与野生鸟类的压力响应相关。我们使用了主要来自于雀形目鸟类的约 1,000 份血液和羽毛样本以及身体质量和翼弦的测量值, 以检验多样化实践对4个生理压力指标的影响, 这些指标分别为异嗜性细胞与淋巴细胞的比率 (H:L)、身体状况、血细胞压积值和鸟类个体的羽毛生长速度。接下来, 我们检验了生理压力指标与 285 项鸟类点计数调查得到的物种丰富度、丰度、出现率和多样性之间的关系。在考虑了其他生物驱动因素后, 我们发现景观环境介导了当地农场管理对 H:L 和身体状况的影响。在密集型农业景观中, 当地的多样化实践伴随着个体压力的降低, 但在被相对较多的半自然区域包围的景观中, 多样化实践则会导致个体压力增加。在以草莓生产为主的景观中, 鸟类羽毛生长更慢, 表明这里的营养状况不如有更多作物类型的景观和半自然区域的景观。没有充足证据表明物种丰富度、丰度、出现率或多样性指标与个体生理压力相关, 这表明对这些指标的依赖可能掩盖了管理对物种续存的影响。我们的研究结果强调了在设计当地管理策略以促进野生动物保护时考虑景观环境的重要性。【翻译: 胡怡思; 审校: 聂永刚】.