Behind the Iron Curtain: Socio-economic and political factors shaped exotic bird introductions into Europe

Little is known about how socio-economic factors quantitatively contribute to shaping introductions of exotic species in space and time. Here, we discover that socio-economic, historical and political factors are largely responsible for shaping exotic bird introductions into Europe. We find that the Cold War and its resulting commercial alliances in Eastern vs. Western Europe led to contrasting patterns in the numbers, composition and origin of birds introduced into each of the two European blocs. The isolation of the Eastern European bloc from the west during the Cold War led to a decline in the number of birds introduced, the number of introduction events and the number of bird species established. Birds introduced during the Cold War originated largely from economically allied countries of each of the two blocs. The Cold War provided a hitherto unexpected benefit to the Eastern European bloc by limiting exotic species introductions, and subsequent population establishment, due to its restrictions on international trade. We suggest that work on the factors shaping invasive species establishment, spread and impacts should incorporate a socio-economic context. Given the ongoing increase in human movement and trade in Europe and the integration of most former Eastern European countries to the European Union, clear policies should be urgently established to prevent inflow of exotic species into formerly more isolated regions and reduce the risk of future biotic invasions.