Scavengers reduce potential brucellosis transmission risk in the Greater Yellowstone Ecosystem

Abstract

AbstractScavengers likely play an important role in ecosystem energy flow as well as disease transmission, but whether they facilitate or reduce disease transmission is often unknown. In the Greater Yellowstone Ecosystem, scavengers are likely to reduce the transmission and subsequent spread of brucellosis within and between livestock and elk by consuming infectious abortion materials, thereby removing the infectious agent from the landscape. We used remote cameras to monitor the time to removal of simulated abortion materials by scavengers at 264 sites from February to June in 2017 and 2018 and assessed the effects of habitat and land management on time to removal in southwest Montana. Time to removal of fetal materials decreased in grassland habitats ( = 2.9 d, credible interval = [1.8–5.0]) in comparison to sagebrush habitats ( = 5.4 d [3.4–9.3]) and forest habitats ( = 5.2 d [3.3–9.0]). In addition, there was an 88% probability that time to removal of fetal materials was slower at sites where mammalian scavengers were actively reduced ( = 6.5 d [3.4–12.8]) compared to sites with no scavenger reduction ( = 4.1 d [2.3–7.8]). Our research indicates that if elk and livestock are commingling during the brucellosis risk period, there is a 90% probability that abortion materials will be removed by scavengers within 16 d across all sites. Coyotes, red foxes, golden and bald eagles, Corvus spp., and turkey vultures were the dominant scavengers, removing 90% of the fetal materials. Actions to maintain the breadth and diversity of scavengers on the landscape are potential management options that could reduce disease transmission risk to livestock in a system where the wildlife reservoir is difficult to address.