Strangers coming from the Sahara: an update of the worldwide distribution, potential impacts and conservation opportunities of alien aoudad

Biological invasions are considered one of the main causes of the current global biodiversity crisis. Many ungulate species have been introduced worldwide, mainly as game animals or e.g. as an attraction in suburban parks. We compiled the available information on distribution, abundance and ecology of the aoudad Ammotragus lervia outside its native range. We showed that the aoudad has established a number of populations in many countries outside its natural range. Alien nuclei have been recorded in at least 10 countries in Europe, Africa and America but it may be an underestimation. Establishment success differs geographically. North American and Spanish populations are large and still expanding, whereas others are small. This difference might be related to a large propagule pressure, but we suggest it might be due to multiple introduction events or better niche suitability. Information on potential impacts of alien populations on natural systems, human activities and disease spread is still scarce. Despite that, the aoudad is already known to be a carrier of parasites, and therefore it has been suggested that further range expansion of the aoudad may affect populations of native ungulates. Alien populations of the aoudad are controlled mainly by hunting, but as it targets mainly weak animals this method may actually improve reproductive success and increase invasive potential. Since prevention, early detection and eradication of small/isolated populations of invasive species are highly recommended, early and selective culling should be carried out to reduce population increase of this alien ungulate.