Impact of Sylvatic Plague Vaccine on Non-target Small Rodents in Grassland Ecosystems Gebbiena M. Bron, 1,2 Katherine L. D. Richgels, 2 Michael D. Samuel, 5 Julia E. Poje, 1,3 Faye Lorenzsonn, 2,4 Jonathan P. Matteson, 1 Jesse T. Boulerice, 6 Jorge E. Osorio, 1 and Tonie E. Rocke 2 1 Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin–Madison, Madison, WI 53705 2 U.S. Geological Survey, National Wildlife Health Center, 6006 Schroeder Road, Madison, WI 53711 3 Department of Forest and Wildlife Ecology, University of Wisconsin–Madison, Madison, WI 53706 4 School of Veterinary Medicine, University of Wisconsin–Madison, Madison, WI 53705 5 Wisconsin Cooperative Wildlife Research Unit, U.S. Geological Survey, University of Wisconsin–Madison, Madison, WI 53706 6 Wyoming Game and Fish Department, 528 South Adams Street, Laramie, WY Abstract: Oral vaccination is an emerging management strategy to reduce the prevalence of high impact infectious diseases within wild animal populations. Plague is a flea-borne zoonosis of rodents that often decimates prairie dog (Cynomys spp.) colonies in the western USA. Recently, an oral sylvatic plague vaccine (SPV) was developed to protect prairie dogs from plague and aid recovery of the endangered black-footed ferret (Mustela nigripes). Although oral vaccination programs are targeted toward specific species, field dis- tribution of vaccine-laden baits can result in vaccine uptake by non-target animals and unintended indirect effects. We assessed the impact of SPV on non-target rodents at paired vaccine and placebo-treated prairie dog colonies in four US states from 2013 to 2015. Bait consumption by non-target rodents was high (70.8%, n = 3113), but anti-plague antibody development on vaccine plots was low (23.7%, n = 266). In addition, no significant differences were noted in combined deer mice (Peromyscus maniculatus) and western harvest mouse (Reithrodontomys megalotis) abundance or community evenness and richness of non-target rodents between vaccine-treated and placebo plots. In our 3-year field study, we could not detect a significant positive or negative effect of SPV application on non-target rodents. Keywords: Plague, Yersinia pestis, Sylvatic plague vaccine, Non-target rodents, Peromyscus, Onychomys leucogaster INTRODUCTION An emerging management strategy to reduce pathogen prevalence in wildlife and decrease disease risk to humans and animals is oral vaccination of wild animal populations. Using this method, carnivores have been immunized for rabies control (Slate et al. 2005), and more recently vaccines Electronic supplementary material: The online version of this article (https://doi. org/10.1007/s10393-018-1334-5) contains supplementary material, which is available to authorized users. Correspondence to: Tonie E. Rocke, e-mail: trocke@usgs.gov EcoHealth https://doi.org/10.1007/s10393-018-1334-5 Original Contribution Ó 2018 This is a U.S. government work and its text is not subject to copyright protection in the United States; however, its text may be subject to foreign copyright protection