Wildlife health and supplemental feeding: A review and management recommendations

Humans provide supplemental food to wildlife under many contexts, ranging from professional feeding areas for game species to backyard bird feeders. Such resources benefit wildlife by providing reliable resources during periods of food shortages, but may also alter the risk of pathogen transmission and development of disease. While several reviews have summarized the detrimental effects of supplemental food on infection risk, we conducted a comprehensive review to quantify support for mechanisms by which intentional wildlife feeding influences host condition (i.e. malnutrition and stress) and pathogen transmission on a global scale and provide a framework to mitigate these risks. We also examined whether the purpose of feeding, whether for game management, conservation, tourism, or in residential areas, influenced health outcomes. We found 115 studies that evaluated the health of wildlife with supplementary feeding, representing 68 species in 35 countries, although nearly half (46% of studies) were from North America. Supplemental feeding tended to increase the risk of pathogen transmission by increasing contact rates between hosts (95%) and promoting pathogen accumulation at feeders or the surrounding environment (77%). Provisioned food was also often a source of immunosuppressive contaminants (80%). Feeding associated with tourism frequently increased wildlife stress, rates of injury, pathogen prevalence, or malnutrition (85%), while feeding for conservation purposes had mostly positive effects on wildlife health (63%). We recommend adopting feeding practices that validate the nutritional appropriateness of wildlife feed for the target species, make food available at lower densities for short periods at unpredictable times and places to prevent aggregation, and avoid feeding during times of migration, pulses of new recruits, and epidemics. These strategies will help retain the recreational and management benefits of wildlife provisioning while mitigating negative effects for many species around the world. (C) 2016 Elsevier Ltd. All rights reserved.