Mapping movements of alien bird species

The global map of alien bird species has been produced for the first time by a UCL-led team of researchers. It shows that human activities are the main determinants of how many alien bird species live in an area but that alien species are most successful in areas already rich with native bird species. 'One of the main ways humans are altering the world is by moving species to new areas where they do not normally occur. Our work shows why humans have been moving these 'alien? bird species around for the last 500 years - primarily through colonialism and the increasingly popular cage bird trade ­- and why some areas end up with more species than others,' explained supervising author, Professor Tim Blackburn (UCL Genetics, Evolution & Environment and ZSL). For the study, published today in PLOS Biology , the researchers collected and analysed data on the movement of almost 1,000 alien bird species between 1500 and 2000 AD. This was used to create a new open access database* which was then analysed for patterns in the context of historical events and natural environmental variation. More than half of all known bird introductions were found to occur after 1950, likely driven by the cage bird trade, and the researchers say this trend is expected to continue.