Where alien birds will go next: environmental factors predict risk

Once a bird has established itself as an alien species in a new region, living alongside native birds, it's most likely to continue spreading to other areas where those same native birds are also present, according to a new UCL-led study. The new study, published in Nature Ecology & Evolution , improves on existing methods to predict the spread of alien species. They found that areas such as the Himalayas and parts of sub-Saharan Africa, which so far have not seen many alien species, could be under threat in coming decades. Senior author Dr Alex Pigot (UCL Centre for Biodiversity & Environment Research) said: "Alien species - those that have been introduced to new areas outside their native range - are one of the leading causes of global biodiversity loss. Driven by human actions, alien species also represent a growing threat to food security, human health and many economies. Predicting where they will spread next, so that we can find ways to mitigate the damage, is an urgent global challenge." The researchers reviewed data from 339 bird species which have already become established as an alien species outside of their native range, distributed all across the globe. To see if they could predict, in hindsight, where these alien species had spread, they first investigated how similar areas across the globe are in terms of their existing native bird species - what is called biotic similarity.