Detection bias in noninvasive track surveys of mammalian predators in Illinois

We compared the species of mammalian predators detected by track surveys using sooted track plates, natural soil, and fine sand as track-collecting substrates. Some species, such as coyotes, foxes, and bobcats, were detected less frequently by track plates than by more natural substrates. In contrast, raccoons and opossums did not show substrate avoidance. Additional data from camera traps and snow tracking in one study did not reveal any spe-cies of mammalian predators not detected by sand stations. Potential sampling bias due to responses of different species to tracking substrate or baits and lures used as attractants should be kept in mind when designing predator surveys.