Habituation, task solving and memorization may facilitate biological invasions: the Starling example

Invasions ecology deals more and more with behavioural characteristics of invasive species. Particularly, research have focused on the personality of invaders and on their way of coping with novelty in new habitats. Traits of neophobia may limit individuals in their exploration of novel objects or the consumption of novel foods, they may stop the access to valuable ressources. Actually, in novel environments like cities, food can be unreachable in throwaway dishes with lids or hidden in the garbage or even close to frightening objects. Animals may either left the place and waste these resources, or they can express low neophobia from the beginning and manipulate the objects to reach food. They may also habituate progressively to the context and use the ressources. Here we analyzed the behavioural responses of individuals from three populations of European starling Sturnus vulgaris: a population anciently settled in a rural region, a population that has recently colonized a urban area and a population of wintering migrant birds. We used a series of tests in order to explore if individuals would habituate to a novel object and if they could remember it eight months later. We explored if individuals would be less neophobic when confronted to two novel objects successively and we tested them in a learning task involving a novel object and an attractive food. Our results show that Sturnus vulgaris habituates rapidly to novel objects and that categorization facilitates neophobia lost when confronted to two different novel objects. Initially young birds appeared to be more skilled than adults in the learning task. Individuals from this species seem to be able to remember an object durably. We suggest that habituation, task solving and memorization are three mechanisms enhancing biological invasions.