Behavioural drivers of survey bias: interactive effects of personality, the perceived risk and device properties.

Detecting small mammal species for wildlife research and management typically depends on animals deciding to engage with a device, for instance, by entering a trap. While some animals engage and are detected, others do not, and we often lack a mechanistic understanding of what drives these decisions. As trappability can be influenced by traits of personality, personality has high potential to similarly influence detection success for non-capture devices (chew-track cards, tracking tunnels, etc.). We present a conceptual model of the detection process where animal behaviours which are detected by different devices are grouped into tiers based on the degree of intimacy with a device (e.g., approach, interact, enter). Each tier is associated with an increase in the perceived danger of engaging with a device, and an increase in the potential for personality bias. To test this model, we first surveyed 36 populations of free-living black rats (Rattus rattus), a global pest species, to uniquely mark individuals (n = 128) and quantify personality traits. We then filmed rat behaviour at novel tracking tunnels with different risk-reward treatments. As predicted, detection biases were driven by personality, the bias increased with each tier and differed between the risk treatments. Our findings suggest that personality biases are not limited to live-capture traps but are widespread across devices which detect specific animal behaviours. In showing that biases can be predictable, we also show biases can be managed. We recommend that studies involving small mammal sampling report on steps taken to manage a personality-driven bias.

A mechanistic understanding of prebaiting to improve interaction with wildlife management devices.

BACKGROUND: Prebaiting is a technique involving early deployment of 'unarmed' devices (e.g. baits and traps) to increase efficacy of wildlife management. Although commonly used, the mechanisms by which prebaiting works are poorly understood. We propose three mechanisms by which prebaiting may increase device interaction probabilities; (1) overcoming neophobia towards novel devices, (2) a 'trickle in' effect increasing time for animals to encounter devices; and (3) social information transfer about rewards associated with devices. We conducted a survey of 100 articles to understand how prebaiting has been used. We then tested our proposed prebaiting mechanisms using a global pest (black rats, Rattus rattus) examining how uniquely marked free-living rats responded to a common yet novel monitoring technique (tracking tunnels). RESULTS: No studies in our dataset tested how prebaiting functioned. Most studies (61%) did not propose a mechanism for prebaiting, but overcoming neophobia was most commonly mentioned. We only found partial support for the overcoming neophobia hypothesis in our field test. We found the dominant mechanism operating in our system to be the 'trickle in' effect with the proportion of individuals visiting the device increasing over time. We found no support for social information transfer as a mechanism of prebaiting. CONCLUSION: Applying a mechanistic understanding of how prebaiting functions will improve the efficacy of management devices. Our results suggest that prebaiting allows time for more rats to encounter a device, hence surveys in our system would benefit from long prebaiting periods. © 2021 Society of Chemical Industry.

Testing transgenerational transfer of personality in managed wildlife populations: a house mouse control experiment.

Pest species control operations are most effective if every individual in a population is targeted. Yet, individual personality drives variation in animal responses to devices such as traps and baits. Failing to account for differences in behavior during control operations may drive a selective removal, resulting in residual animals with biased expressions of personality. If these biased traits are passed onto offspring, control operations would become increasingly problematic. To test if biased trait expressions in founding populations are passed on to offspring, we quantified personality traits in wild-caught house mice (Mus musculus) and created founder populations selected for biased (high, low) or intermediate expressions of activity. We released the behaviorally biased populations into outdoor yards to breed to the F1 generation and, 10 weeks later, removed the mice and quantified the personality traits of the offspring. Despite the strong personality bias in founder populations, we observed no transgenerational transfer of personality and detected no personality bias in the F1 generation. Our results provide reassuring evidence that a single intensive control operation that selects for survivors with a personality bias is unlikely to lead to a recovering population inherently more difficult to eradicate, at least for house mice.