Abstract
Invasive mammalian predators are linked to terrestrial vertebrate extinctions worldwide. Prey naïveté may explain the large impact invasive predators have on native prey; prey may fail to detect and react appropriately to the cues of novel predators, which results in high levels of depredation. In Australia, the feral cat (Felis catus) and the red fox (Vulpes vulpes) are implicated in more than 30 animal extinctions and the naïveté of native prey is often used to explain this high extinction rate. Reptiles are one group of animals that are heavily preyed upon by F. catus and V. vulpes. However, very few studies have examined whether reptiles are naive to their cues. In this study, we examine the ability of two native reptile species (Morethia boulengeri and Christinus marmoratus) to detect and distinguish between the chemical cues of two invasive predators (V. vulpes and F. catus) and three native predators (spotted-tailed quoll, Dasyurus maculatus; dingo, Canis lupus dingo; eastern brown snake, Pseudonaja textilis), as well as two non-predator controls (eastern grey kangaroo, Macropus giganteus and water). We conducted experiments to quantify the effects of predator scents on lizard foraging (the amount of food eaten) during 1 h trials within Y-maze arenas. We found both study species reduced the amount they consumed when exposed to predator scents—both native and invasive—indicating that these species are not naive to invasive predators. An evolved generalized predator-recognition system, rapid evolution or learned behaviour could each explain the lack of naïveté in some native Australian reptiles towards invasive predators.
Highlights
Invasive mammalian predators are linked to terrestrial vertebrate extinctions worldwide
The ability of prey to accurately recognize olfactory cues and deploy anti-predator response is vital for avoiding predation, yet prey that have not co-evolved with a particular predator species may be naive to olfactory cues [9]
A key finding of our study is that both prey species responded to the olfactory cues of invasive predators in a way that is likely to diminish the risk of predation
Summary
Invasive mammalian predators are linked to terrestrial vertebrate extinctions worldwide. In Australia, the feral cat (Felis catus) and the red fox (Vulpes vulpes) are implicated in more than 30 animal extinctions and the naıveteof native prey is often used to explain this high extinction rate. Prey naıveteis highly problematic when a predator is introduced to a new region, as it can expose native prey to an enhanced risk of depredation [10,11] This may explain why invasive predators have had such a devastating impact on native prey—for example, Doherty et al [12] found that invasive mammalian predators are implicated in 58% of modern extinctions of birds, mammals and reptiles. There is some evidence to support this—Spencer [11] found that Murray River turtles (Emydura macquarii) failed to change their nesting behaviour to minimize the predation risk of offspring when exposed to olfactory cues of introduced red foxes, but did change their behaviour when exposed to olfactory cues of the native eastern quoll (Dasyurus viverrinus)
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