Increased Visitation at Urban Water Sources by Bats and Raccoons: Implications for Cross-species Transmission of Rabies

Abstract

Abstract We examined the potential for urban water sources to act as centers for rabies transmission from bats to mesocarnivores in the arid southwestern United States where free water is often limited. Because residential housing can act as den and roost sites for both mesocarnivores and bats, we also examined the effect of housing density on abundance. Using ultrasonic acoustic recorders to assess bat activity and camera traps to estimate mesocarnivore abundance, we compared 14 pairs of wet and dry locations over two years by surveying twice during the summer, once prior to summer monsoons and once during the monsoon season, when surface waters were more available. Number of calls for all bat species combined were greater at wet sites compared to dry sites and calls of two bat species often associated with rabies, big brown bat (Eptesicus fuscus) and silver-haired bat (Lasionycteris noctivagans), were recorded more at wet sites than dry sites in the monsoon season. In both years, raccoons (Procyon lotor) were photographed more often at wet sites while striped skunks (Mephitis mephitis) and gray foxes (Urocyon cinereoargenteus) were less likely to be detected at wet sites. Bat, fox and raccoon abundance was not associated with housing density while striped skunks showed a positive correlation with housing density. Higher abundance of bats at urban waters could increase potential for cross-species transmission of rabies from bats to mesocarnivores primarily for raccoons.