Case study of the spatial relationship between bat pass frequency and artificial light pollution along a bike trail in Portage County, Ohio

Abstract

Northeastern Ohio bats are important in maintaining insect populations, thus minimizing crop damage. However, because bat populations are decreasing due to factors such as habitat loss and White Nose Syndrome, attention should be placed on evaluating habitat requirements to maximize conservation efforts. Understanding anthropogenic disturbances such as ecological light pollution, as an indicator of bat habitat quality, has been historically neglected. Studies have shown that the presence of light pollution can alter the activity of several animals, including bats (Frank 1988; Svensson and Rydell 1998; Yurk and Trites 2000; Rydell 2006; Santos and others 2010). To better understand the effects of light pollution on bat activity, this study examined frequency of bat activity along a light gradient at a field site in Portage County, Ohio in the summer of 2014. Spatial modeling of bat pass frequency suggested greatest activity in regions of medium light intensities, versus high and low light intensities. A preliminary species identification study indicated the presence of hoary, eastern red, and big brown bats, all of which tend to prefer lit environments and thus are likely foraging in the lit areas at the field site. As activity was lowest in the brightest areas, a threshold might exist beyond which light-tolerant bats at this site will avoid. Light-avoiding species present in Portage County and neighboring Summit and Trumbull Counties may be deterred by the light gradient at the field site. This study suggests that artificial light may be a variable of concern for bat populations at this location and that the effects of light should be studied further to better understand how different bat species react to light. Moreover, bat species composition should be determined at the field site in order to promote holistic bat habitat management plans.