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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'. [ABSTRACT FROM AUTHOR]

Enteric illnesses remain the second largest source of communicable diseases worldwide, and wild birds are suspected sources for human infection. This has led to efforts to reduce pathogen spillover through deterrence of wildlife and removal of wildlife habitat, particularly within farming systems, which can compromise conservation efforts and the ecosystem services wild birds provide. Further, Salmonella spp. are a significant cause of avian mortality, leading to additional conservation concerns. Despite numerous studies of enteric bacteria in wild birds and policies to discourage birds from food systems, we lack a comprehensive understanding of wild bird involvement in transmission of enteric bacteria to humans. Here, we propose a framework for understanding spillover of enteric pathogens from wild birds to humans, which includes pathogen acquisition, reservoir competence and bacterial shedding, contact with people and food, and pathogen survival in the environment. We place the literature into this framework to identify important knowledge gaps. Second, we conduct a meta‐analysis of prevalence data for three human enteric pathogens, Campylobacter spp., E. coli, and Salmonella spp., in 431 North American breeding bird species. Our literature review revealed that only 3% of studies addressed the complete system of pathogen transmission. In our meta‐analysis, we found a Campylobacter spp. prevalence of 27% across wild birds, while prevalence estimates of pathogenic E. coli (20%) and Salmonella spp. (6.4%) were lower. There was significant bias in which bird species have been tested, with most studies focusing on a small number of taxa that are common near people (e.g. European starlings Sturnus vulgaris and rock pigeons Columba livia) or commonly in contact with human waste (e.g. gulls). No pathogen prevalence data were available for 65% of North American breeding bird species, including many commonly in contact with humans (e.g. black‐billed magpie Pica hudsonia and great blue heron Ardea herodias), and our metadata suggest that some under‐studied species, taxonomic groups, and guilds may represent equivalent or greater risk to human infection than heavily studied species. We conclude that current data do not provide sufficient information to determine the likelihood of enteric pathogen spillover from wild birds to humans and thus preclude management solutions. The primary focus in the literature on pathogen prevalence likely overestimates the probability of enteric pathogen spillover from wild birds to humans because a pathogen must survive long enough at an infectious dose and be a strain that is able to colonize humans to cause infection. We propose that future research should focus on the large number of under‐studied species commonly in contact with people and food production and demonstrate shedding of bacterial strains pathogenic to humans into the environment where people may contact them. Finally, studies assessing the duration and intensity of bacterial shedding and survival of bacteria in the environment in bird faeces will help provide crucial missing information necessary to calculate spillover probability. Addressing these essential knowledge gaps will support policy to reduce enteric pathogen spillover to humans and enhance bird conservation efforts that are currently undermined by unsupported fears of pathogen spillover from wild birds. [ABSTRACT FROM AUTHOR]

Agricultural intensification is a leading threat to bird conservation. Highly diversified farming systems that integrate livestock and crop production might promote a diversity of habitats useful to native birds foraging across otherwise‐simplified landscapes. At the same time, these features might be attractive to nonnative birds linked to a broad range of disservices to both crop and livestock production. We evaluated the influence of crop–livestock integration on wild bird richness and density along a north‐south transect spanning the U.S. West Coast. We surveyed birds on 52 farms that grew primarily mixed vegetables and fruits alone or integrated livestock into production. Crop–livestock systems harbored higher native bird density and richness relative to crop‐only farms, a benefit more pronounced on farms embedded in nonnatural landscapes. Crop–livestock systems bolstered native insectivores linked to the suppression of agricultural pest insects but did not bolster native granivores that may be more likely to damage crops. Crop–livestock systems also significantly increased the density of nonnative birds, primarily European Starlings (Sturnus vulgaris) and House Sparrows (Passer domesticus) that may compete with native birds for resources. Models supported a small, positive correlation between nonnative density and overall native bird density as well as between nonnative density and native granivore density. Relative to crop‐only farms, on average, crop–livestock systems exhibited 1.5 times higher patch richness, 2.4 times higher density of farm structures, 7.3 times smaller field sizes, 2.4 times greater integration of woody crops, and 5.3 times greater integration of pasture/hay habitat on farm. Wild birds may have responded to this habitat diversity and/or associated food resources. Individual farm factors had significantly lower predictive power than farming system alone (change in C statistic information criterion (ΔCIC) = 80.2), suggesting crop–livestock systems may impact wild birds through a suite of factors that change with system conversion. Collectively, our findings suggest that farms that integrate livestock and crop production can attract robust native bird communities, especially within landscapes devoted to intensified food production. However, additional work is needed to demonstrate persistent farm bird communities through time, ecophysiological benefits to birds foraging on these farms, and net effects of both native and nonnative wild birds in agroecosystems. [ABSTRACT FROM AUTHOR]

Background: Maternal antibodies are believed to play an integral role in protecting immunologically immature wildpasserines from environmental antigens. This study comprehensively examines the early development of the adaptive immune system in an altricial-developing wild passerine species, the house sparrow (Passer domestics), by characterizing the half-life of maternal antibodies in nestling plasma, the onset of de novo synthesis of endogenous antibodies by nestlings, and the timing of immunological independence, where nestlings rely entirely on their own antibodies for immunologic protection. Methodology/Principal Findings: In an aviary study we vaccinated females against a novel antigen that these birds would not otherwise encounter in their natural environment, and measured both antigen-specific and total antibody concentration in the plasma of females, yolks, and nestlings. We traced the transfer of maternal antibodies from females to nestlings through the yolk and measured catabolisation of maternal antigen-specific antibodies in nestlings during early development. By utilizing measurements of non-specific and specific antibody levels in nestling plasma we were able to calculate the half-life of maternal antibodies in nestling plasma and the time point at which nestling were capable of synthesizing antibodies themselves. Based on the short half-life of maternal antibodies, the rapid production of endogenous antibodies by nestlings and the relatively low transfer of maternal antibodies to nestlings, our findings suggest that altricialdeveloping sparrows achieve immunologic independence much earlier than precocial birds. Conclusions/Significance: To our knowledge, this is the first in depth analyses performed on the adaptive immune system of a wild-passerine species. Our results suggest that maternal antibodies may not confer the immunologic protection or immune priming previously proposed in other passerine studies. Further research needs to be conducted on other altricial passerines to determine if the results of our study are a species-specific phenomenon or if they apply to all altricialdeveloping birds. [ABSTRACT FROM AUTHOR]

Abstract: Establishment and spread of Ornithonyssus sylviarum were documented through time on sentinel hens (50 per house of 28,000–30,000 hens) in the first egg production cycle of three large commercial flocks (12 houses) of white leghorn hens. Mites were controlled using acaricide, and the impacts of treatment on mite populations and economic performance were documented. Mite prevalence and intensity increased rapidly and in tandem for 4–8 weeks after infestation. Intensity declined due to immune system involvement, but prevalence remained high, and this would affect mite sampling plan use and development. Early treatment was more effective at controlling mites; 85% of light infestations were eliminated by a pesticide spray (Ravap), versus 24% of heavy infestations. Hens infested later developed lower peak mite intensities, and those mite populations declined more quickly than on hens infested earlier in life. Raw spatial association by distance indices (SADIE), incorporating both the intensity and distribution of mites within a house, were high from week-to-week within a hen house. Once adjusted spatially to reflect variable hen cohorts becoming infested asynchronously, this analysis showed the association index tended to rebound at intervals of 5–6 weeks after the hen immune system first suppressed them. Large, consistent mite differences in one flock (high vs. low infestation levels) showed the economic damage of mite parasitism (assessed by flock indexing) was very high in the initial stages of mite expansion. Unmitigated infestations overall reduced egg production (2.1–4.0%), individual egg weights (0.5–2.2%), and feed conversion efficiency (5.7%), causing a profit reduction of $0.07–0.10 per hen for a 10-week period. Asynchronous infestation patterns among pesticide-treated hens may have contributed to a lack of apparent flock-level economic effects later in the production cycle. Individual egg weights differed with mite loads periodically, but could be either higher or lower, depending on circumstances and interactions with hen weight. Individual hen weight gains were depressed by high/moderate mite loads, but the heavier hens in a flock harbored more mites. This led to compensatory weight gains after mites declined. Tradeoffs between resource allocation to body growth or production versus immune system function appeared to be operating during the early and most damaging mite infestation period, when high egg production was beginning and the hens were gaining weight. The results were related to other studies of mite impact on domestic hens and to wild bird–ectoparasite studies. Much of the mite economic damage probably is due to engaging and maintaining the immune response. [Copyright &y& Elsevier]

Growers may be more likely to adopt wildlife-friendly practices if they perceive that beneficial species are present and conservation actions are successful. At the same time, a farm's landscape and regional context may influence whether biodiversity, including wild birds, are likely to provide ecosystem services or disservices. Here, across two Bird Conservation Regions in the western USA, we assessed a feedback loop that links growers' attitudes towards birds, farming practices, and bird assemblages' hypothesized impacts. To do so, we paired a grower questionnaire survey, bird point count surveys, and farm management and landscape classifications. We found that growers generally exhibited more positive attitudes towards raptors than songbirds and allies (e.g., flycatchers, woodpeckers, hummingbirds). Attitudes towards raptors were more positive when farms were embedded in more natural landscapes and had greater proportions of nonnative birds. Growers held more positive attitudes towards songbirds and allies related to production (yields, crop quality, insect control) when their farms were in the Northern Pacific Rainforest region and were embedded in more natural landscapes. Growers' attitudes towards songbirds and allies related to disease/infrastructure (food safety, animal disease, building/machinery damage, vertebrate control) were more positive in the Northern Pacific Rainforest region as landscapes became more natural, but these relationships did not hold for Coastal California. However, growers' attitudes towards birds were mostly unrelated to the practices used on the farm. Understanding these feedback loops is crucial to increasing uptake of and retention in conservation programs for rapidly declining farmland bird communities. • We link growers' attitudes, bird communities, and bird ecological roles on farms. • Grower attitudes were influenced by the ecological roles of birds on-farm. • Growers with positive attitudes towards birds managed farms with higher conservation value. • Promoting beneficial birds in less natural landscapes may improve attitudes and conservation. [ABSTRACT FROM AUTHOR]