Learning and experience drive predatory success in a wild olfactory predator, the black rat Rattus rattus

Some individuals within a predator population inflict disproportionate impacts on prey. Undermining the behaviour of these ‘rogues’ is crucial when prey is of conservation concern, but challenging when little is understood about how these behaviours develop or their prevalence among demographic groups. We undertook a multi-stage experiment with wild black rats Rattus rattus to test if experience created ‘rogue’ individuals and then if subsequent predatory behaviour differed. Individually marked rats were exposed to quail eggs on multiple nights during an initial training phase, then an unrewarding bird odour for several nights before exposure to another quail egg. Rats that found multiple eggs during the initial training phase continued to hunt eggs in the final phase, but individuals finding only one egg initially did not. Our results underline the importance of reinforcement in foraging behaviour within wild animals, suggesting that ‘rogue’ behaviour is facilitated by repeat experiences and may be difficult to undermine once developed.

捕食者种群中的部分个体，会对猎物造成远超其种群占比的影响。当猎物为保护物种时，管控这类‘异类掠食者（rogues）’的行为至关重要，但由于我们对这类行为的形成机制，或是其在种群不同类群中的流行程度知之甚少，相关工作往往极具挑战性。我们针对野生黑家鼠（Rattus rattus）开展了多阶段实验，以验证过往经历是否会催生‘异类掠食者（rogues）’，以及后续的掠食行为是否会因此产生差异。在初始训练阶段，佩戴个体标记的黑家鼠需在多晚的时间内接触鹌鹑卵；随后，让它们连续数晚接触无奖励的鸟类气味，之后再将其暴露于鹌鹑卵环境中。初始训练阶段中找到多枚鹌鹑卵的个体，在最终阶段仍会持续猎食鸟卵；而初始阶段仅找到一枚卵的个体则未表现出此类行为。我们的研究结果凸显了野生动物觅食行为中强化机制的重要性，表明‘异类掠食者’行为可通过重复经历得以强化，且一旦形成便难以被削弱。