Pattern of distribution of the American bullfrog Rana catesbeiana in Europe

Despite early reports of its presence, no recent data exist on the distribution of the American bullfrog in Europe, the causes of introduction, or the trends of populations. We monitored the European situation at two spatial scales. In SW France, we performed call surveys over 2,500 wetlands. We found bullfrogs over about 2,000 km2, apparently the European area in which the strongest expansion of bullfrogs is taking place. In addition, we used questionnaires to investigate the situation at the continental scale. At least 25 independent introductions occurred in Europe; eradication attempts were successful three times, and bullfrog populations are present in five countries. Education programs and monitoring are necessary to reduce the rate of introduction and to start management action as soon as possible.