Consequences of Anthropogenic Resources for the Cross-Scale Dynamics of an Enteric Pathogen in an Avian Host

城市化正在全球范围内扩张，预计未来40年，全球三分之二的人口将居住在城市。城市化导致许多野生动物物种减少，但一些物种利用城市和郊区栖息地人类提供的新资源，特别是食物。野生动物生态因人类有意（如鸟类饲养者）或意外（如垃圾）喂食而发生的变化，可改变它们对传染病的暴露程度和易感性。当人类提供的食物导致野生动物高密度聚集，并与它们自然不会接触的物种混合，增加它们接触病原体的机会时，就会发生这种情况。补充饲料还可以通过增强身体状况和免疫防御来影响动物抵抗感染的能力；另外，人类改变的饮食可能会改变它们肠道细菌的组成，增加它们对感染的易感性。该研究项目直接研究了提供给野生动物的食物是否会改变它们与病原体的相互作用，从个体宿主的定植到疾病在景观中的传播，以及与人类相关的疾病风险。研究人员将重点研究肠道病原体沙门氏菌与南佛罗里达州白鹮之间的相互作用；这些涉禽最近从在天然湿地觅食转向城市公园，在那里它们以剩饭和人们的施舍为生。研究人员将使用实验、实地观察和无线电跟踪技术来调查城市饮食如何通过改变个体鸟类的状况和免疫防御，以及白鹮在不同地点和栖息地类型的运动和群集行为来影响沙门氏菌感染。将建立数学模型来预测与城市公园中人类喂养有关的感染传播。通过城市白朱鹭的高知名度和公众吸引力，研究人员将让公民科学家志愿者报告他们的观察结果，并将参与外展工作，向公众宣传喂养野生动物对健康的影响。这个跨学科项目也将为本科生、研究生和研究专业人员提供大量培训机会，包括来自代表性不足群体的个人。这项研究代表了迄今为止最全面的研究，即在人类主导的栖息地中，野生动物对食物资源变化的反应如何影响它们与传染病的相互作用。活动包括实地研究、圈养挑战实验和数学建模，以解决三个问题：(i)供应如何影响病原体的易感性、脱落和对个体宿主的影响？（二）供应如何影响地方规模的接触和传播动态？（iii）在景观水平上，供应如何改变宿主运动、病原体传播和影响？第一个问题将通过量化个人层面的饮食、免疫防御、病原体脱落和城市和自然栖息地的状况/健康指标来回答。研究人员将通过野生和圈养鸟类进一步测试胃肠道微生物群是否依赖于饮食和栖息地类型。第二个问题将通过宿主接触的测量来解决，包括城市和自然栖息地的种群规模和物种组成，并通过测量沙门氏菌的流行率和基因型来解决。第三个问题将通过使用地理空间跟踪技术和公民科学报告来描述朱鹭的运动特征，并确定栖息地使用和感染指标的生态相关性来解决。实地和实验工作将直接为将饮食与病原体传播联系起来的数学模型提供信息，以预测感染流行率和影响的变化。这一建模框架可以更广泛地应用于了解其他野生动物物种及其病原体如何应对未来的城市化和食物资源的相关变化。

Urbanization is expanding at a global scale, with two-thirds of the world's people expected to reside in cities in the next 40 years. Urbanization causes many wildlife species to decline, but some species capitalize on new resources, especially food, provided by humans in urban and suburban habitats. Shifts in wildlife ecology in response to intentional (e.g., bird feeders) or accidental (e.g., garbage) feeding by humans can alter their exposure and susceptibility to infectious diseases. This can happen when human-provided food causes wildlife to gather at high densities and mix with species they naturally would not contact, increasing their exposure to pathogens. Supplemental feeding could also affect an animal's ability to fight infection by boosting body condition and immune defense; alternatively, human-altered diets might change the makeup of their gut bacteria and increase their, susceptibility to infection. This research project directly examines whether food provided to wildlife changes their interactions with pathogens, from the colonization of individual hosts to disease spread across the landscape, with associated disease risks for humans. The researchers will focus on interactions between the gut pathogen Salmonella and White Ibis in South Florida; these wading birds have recently shifted from feeding in natural wetlands to urban parks, where they subsist on leftover food and handouts from people. The researchers will use experiments, field observations and radio-tracking technology to investigate how urban diet influences Salmonella infection through changes in condition and immune defense of individual birds, and movement and flocking behaviors of White Ibis across different sites and habitat types. Mathematical models will be developed to forecast the spread of infection in relation to human feeding in urban parks. Through the high visibility and public appeal of urban White Ibises, the researchers will involve citizen scientist volunteers in reporting their observations, and will engage in outreach efforts to educate the public on the health-related effects of feeding wildlife. This interdisciplinary project will also provide numerous opportunities for training undergraduates, graduate students, and research professionals, including individuals from underrepresented groups.This research represents the most comprehensive study to date of how wildlife responses to changing food resources in human-dominated habitats influence their interactions with infectious diseases. Activities integrate field studies, captive challenge experiments and mathematical modeling to address three questions: (i) How does provisioning influence pathogen susceptibility, shedding, and impacts on individual hosts? (ii) How does provisioning influence local-scale contacts and transmission dynamics? and (iii) How does provisioning alter host movements, pathogen transmission and impacts at the landscape level? The first question will be answered by quantifying individual-level diet, immune defense, pathogen shedding and indicators of condition/health in urban and natural habitats. The researchers will further test whether gastrointestinal microbiota depend on diet and habitat type through work with wild and captive birds. The second question will be addressed through measures of host contact, including flock size and species composition in urban and natural habitats, and by measuring the prevalence and genotypes of Salmonella. The third question will be addressed by using geospatial tracking technology and citizen science reporting to characterize the movements of ibises, and identify ecological correlates of habitat use and infection metrics. Field and experimental work will directly inform a mathematical model that links diet to pathogen spread, to predict changes in infection prevalence and impacts. This modeling framework can be applied more broadly to understand how other wildlife species and their pathogens might respond to future urbanization and associated shifts in food resources.