Letters to Nature

Nature 414, 195-197 (8 November 2001) | doi:10.1038/35102557; Received 28 June 2001; Accepted 18 September 2001

Determinants of establishment success in introduced birds

Tim M. Blackburn1 & Richard P. Duncan2

  1. School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
  2. Ecology and Entomology Group, Soil, Plant & Ecological Sciences Division, PO Box 84, Lincoln University, Canterbury, New Zealand

Correspondence to: Tim M. Blackburn1 Correspondence and requests for materials should be addressed to T.M.B. (e-mail: Email: t.blackburn@bham.ac.uk).

A major component of human-induced global change is the deliberate or accidental translocation of species from their native ranges to alien environments1, 2, where they may cause substantial environmental and economic damage3, 4. Thus we need to understand why some introductions succeed while others fail. Successful introductions tend to be concentrated in certain regions2, especially islands and the temperate zone, suggesting that species-rich mainland and tropical locations are harder to invade because of greater biotic resistance1, 5, 6, 7, 8, 9. However, this pattern could also reflect variation in the suitability of the abiotic environment at introduction locations for the species introduced3, 9, 10, 11, coupled with known confounding effects of nonrandom selection of species and locations for introduction8, 12, 13, 14. Here, we test these alternative hypotheses using a global data set of historical bird introductions, employing a statistical framework that accounts for differences among species and regions in terms of introduction success. By removing these confounding effects, we show that the pattern of avian introduction success is not consistent with the biotic resistance hypothesis. Instead, success depends on the suitability of the abiotic environment for the exotic species at the introduction site.