The timid invasion: Behavioural adjustments and range expansion in a non-native rodent

Animal behaviour can moderate or favour biological invasion processes, and the native fauna’s ability to adapt. The importance of behavioural traits for colonization success remains debated, as well as the nature of behavioural traits that facilitate colonization. We investigated behavioural responses associated with risk-taking and exploration, in both non-native bank voles (Myodes glareolus, N = 225) accidentally introduced to Ireland a century ago, and in native wood mice (Apodemus sylvaticus, N = 189), that decline in numbers with vole expansion.
We repeatedly sampled behavioural responses in three colonization zones: source (2 sites), expansion edge (4) and pre-arrival(2).  Only source and edge zones are occupied by bank voles, for more than 80 years and 1-4 years, respectively.
Individuals of both species varied consistently in risk-taking and exploration, and mice had not adjusted their behaviour to the presence of non-native voles, as their behaviour did not differ between the..., Trapping
Rodents were trapped in single-capture Longworth traps (Penlon Ltd., Oxford, UK) which were pre-baited with seeds from commercial bird feed for 2 nights prior to trapping. At each site, 24 traps were set in lines with 10 m spacing between them. Traps were baited and set overnight and checked and deactivated in the morning. Animals were kept inside their traps in the shade until testing, with replenished food and pieces of carrots and cucumber as water sources. Trapping was not conducted during rainy days. Sites were visited for two trapping sessions within 4 days and re-visited after 2–4 weeks to allow repeated testing on recaptured individuals. 

Behavioural tests

For behavioural testing, we adopted two standardized behavioural tests that are commonly used in animal personality studies of small mammals to assess boldness and spatial exploration in a novel environment. The set-up combined the dark-light test and the open-field test and was adjusted to be executed under field c..., Standard programm to open tables (e.g. Excel, OpenOffice Calc)., # The timid invasion: Behavioural adjustments and range expansion in a non-native rodent

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The dataset contains data on bank vole and wood mouse individuals captured on different sites in Ireland. Sites differed based on whether or not the invasive bank vole was present and for how long the invasive species had already been present. Captured individuals were tested in behavioural tests to assess exploration and risk-taking behaviour. Behavioural data was sampled repeatedly. Individuals of both species varied consistently in risk-taking and exploration, and mice had not adjusted their behaviour to the presence of invasive non-native voles, as their behaviour did not differ between the zones.
Voles at the expansion edge were initially more risk-averse but habituated to repeated testing situation, compared to voles that were consistently less timid risk-averse in the source population, indicating spatial sorting for risk-taking propensity along the expansion front

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