Invasive species (species that have successfully overcome the barriers of transport, introduction, establishment, and spread) are a risk to biodiversity and ecosystem function. Introduction effort is one of the main factors attributed to invasion success, but life history traits are also important as they influence population growth. In this contribution, we first investigated life history traits of the Barbary ground squirrel, Atlantoxerus getulus, a species with a remarkably low introduction

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... ffort, and studied whether their exceptional invasion success is due to a very fast life history profile through a comparison of these traits to other successfully invaded mammals. We then examined whether number of founders and/or a fast life history influences invasion success of squirrels. We found that Barbary ground squirrels were on the fast end of the fast-slow continuum, but their life history is not the only contributing factor for their invasion success, as the life history profile is comparable to other invasive species that do not have such a low introduction effort. We also found that neither life history traits nor number of founders explained invasion success of introduced squirrels in general. These results contradict the concept that introduction effort is the main factor explaining invasion success, especially in squirrels. Instead, we argue that invasion success can be influenced by multiple aspects of the new habitat or the biology of the introduced species.