Differential behavioural flexibility in response to predation risk in native and introduced tropical savannah rodents

Differential predation risk between habitats, or 'the landscape of fear', can have profound impacts on foraging strategies of prey. Few studies, however, have described the landscape of fear in the wild, in relation to predator densities. Using giving-up density experiments, and vertebrate surveys, we described the landscape of fear for two rodent species in relation to actual predator abundances in a tropical savannah. We offered native eastern chestnut mice, Pseudomys gracilicaudatus, and introduced house mice, Mus musculus domesticus, food in the open, and under the cover of grass. When eastern brown snakes, Pseudonaja textilis, were absent, both eastern chestnut and house mice consumed more food items under grass. In habitats where snakes were abundant, however, eastern chestnut mice changed their foraging behaviour, and consumed more food items in the open than under grass. In contrast, non-native house mice reduced their foraging activity under cover, but showed no increase in foraging in the open in the presence of snakes. Thus, native eastern chestnut mice have the ability to change their foraging tactics to adjust their antipredator behaviour to remain successful in the presence of native eastern brown snakes, whereas introduced house mice did not exhibit this behaviour.