Increasing predation risk with light reduces speed, exploration and visit duration of invasive ship rats (Rattus rattus)

Exploiting predation cues to deter pests remains an untapped management tool for conservationists. We examined foraging and movement patterns of 20 wild ship rats (Rattus rattus) within a large, outdoor ‘U maze’ that was either illuminated or dark to assess if light (an indirect predation cue) could deter rodents from ecologically vulnerable locations. Light did not alter rats’ foraging behaviour (latency to approach seed tray, visits to seed tray, time per visit to seed tray, total foraging duration, foraging rate) within the experimental resource patch but three of seven movement behaviours were significantly impaired (53% fewer visits to the maze, 70% less exploration within the maze, 40% slower movement within the maze). The total time males spent exposed to illumination also declined by 45 minutes per night, unlike females. Individual visits tended to be longer under illumination, but the latency to visit and the latency to cross through the U maze were unaffected by illumination. Elevating predation risk with illumination may be a useful pest management technique for reducing ship rat activity, particularly in island ecosystems where controlling mammalian predators is paramount to preserving biodiversity.