Ecology: The recipe for a successful ‘alien’ bird invasion

‘Alien’ bird species are most likely to survive in a new habitat if the environmental conditions are similar to those in its native home, reveals a study in this week’s Nature. The research, which provides a vital insight into the conditions that help some non-native species to thrive, should assist those who seek to curb future invasions.

As human activity continues to reshape the world, non-native species are becoming more of a problem. Alien species sometimes out-compete their native counterparts, and this can lead to the extinction of native species, but it is unclear why some alien species flourish whilst others flounder.

Tim Blackburn and colleagues examined data from more than 4,000 introduction events involving over 700 species of bird. They found that environmental factors are the most important determinant in helping an invasive species to become established. This includes the local climate and the presence of other alien species. Alien species are more likely to settle if they are already pre-adapted to local climatic conditions, and if other alien species are already established. Other factors, such as brood size and the size of the founding population, have a lesser role.

As global trade grows and more species are transported around the world, there will be more opportunities for alien species to establish themselves. The authors highlight the need for enhanced management programmes to prevent or mitigate the negative impacts of these invasions.