Abstract
Individual variation in behavioural traits (including responses to social cues) may influence the success of invasive populations. We studied the relationship between sociality and personality in invasive cane toads (Rhinella marina) from a recently established population in tropical Australia. In our field experiments, we manipulated social cues (the presence of a feeding conspecific) near a food source. We captured and compared toads that only approached feeding sites where another toad was already present, with conspecifics that approached unoccupied feeding sites. Subsequent laboratory trials showed correlated personality differences (behavioural syndromes) between these two groups of toads. For example, toads that approached already-occupied rather than unoccupied feeding sites in the field, took longer to emerge from a shelter-site in standardized trials, suggesting these individuals are ‘shy’ (whereas toads that approached unoccupied feeding stations tended to be ‘bold’). Manipulating hunger levels did not abolish this difference. In feeding trials, a bold toad typically outcompeted a shy toad under conditions of low prey availability, but the outcome was reversed when multiple prey items were present. Thus, both personality types may be favored under different circumstances. This invasive population of toads contains individuals that exhibit a range of personalities, hinting at the existence of a wide range of social dynamics in taxa traditionally considered to be asocial.
Highlights
Many scientific studies have attempted to predict ecological traits that render a species more or less likely to become a successful invader [1,2,3,4]
The time taken for a toad to approach the experimental light was influenced by the presence of a conspecific already feeding under the light, demonstrating that social facilitation occurs in free-ranging cane toads
We identified variation in foraging decisions made by freeranging cane toads, based upon their sociality level as evaluated by their willingness to approach a novel unoccupied foraging site
Summary
Many scientific studies have attempted to predict ecological traits that render a species more or less likely to become a successful invader [1,2,3,4]. Behavioural traits such as ‘personality’ have been included only recently in this context [3,4,5,6,7,8,9]. Bold organisms may be more prone to explore the new area, to utilize resources in highly disturbed sites, or to displace native competitors from preferred resources [6,10,11]. Range expansion in passerine birds (Sialia mexicana) is related to behavioural traits: more aggressive individuals displace interspecific competitors from places that eventually are occupied by less aggressive individuals [13]
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