Native predators can learn new prey cues to overcome naivete and hunt novel alien prey

Abstract

Biological invasions continue to rise globally, increasing the frequency of novel ecological interactions and the potential for naivete. Native predators can defend against invasion by alien prey species through biotic resistance, but initial predator naivete towards novel alien prey can allow prey to establish. Here we test if predator naivete can be overcome via a learned association between novel prey cues and a food reward, and if this conditioning increases predator motivation to hunt novel alien prey. We exposed free-living native bush rats (Rattus fuscipes) to repeated bouts of novel alien cockroach (Nauphoeta cinerea) odour and food rewards over an 11-day training period. We then conducted a simulated invasion, comparing the survival rates of sentinel cockroach prey in sites with trained and untrained rats. Cockroaches in sites with trained rats were 46 % more likely to be found and consumed over the invasion period than prey in sites with untrained rats. Also, the number of food rewards taken during training was correlated with the number of prey consumed on the first night of the invasion. Our results suggest that predators can overcome their naivete to novel prey through learning and that pre-exposing free-living predators to novel prey cues can subsequently increase predation rates on novel alien prey.