title: Human impacts and the global distribution of extinction risk.
abstract: Understanding the global geographical distribution of extinction risk is a key challenge in conservation biology. It remains controversial, however, to what extent areas become threat hotspots simply because of high human impacts or due to predisposing ecological conditions. Limits to the taxonomic and geographical extent, resolution and quality of previously available data have precluded a full global assessment of the relative roles of these factors. Here, we use a new global database on the geographical distributions of birds on continents and continental islands to show that, after controlling for species richness, the best predictors of the global pattern of extinction risk are measures of human impact. Ecological gradients are of secondary importance at a global scale. The converse is true for individual biogeographic realms, within which variation in human impact is reduced and its influence on extinction risk globally is therefore underestimated. These results underline the importance of a global perspective on the mechanisms driving spatial patterns of extinction risk, and the key role of anthropogenic factors in driving the current extinction crisis.
authors.affiliation: Biodiversity & Macroecology Group, Department of Animal & Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK.
authors.forename: Richard G
authors.initials: RG
authors.lastname: Davies
authors.forename: C David L
authors.initials: CD
authors.lastname: Orme
authors.forename: Valerie
authors.initials: V
authors.lastname: Olson
authors.forename: Gavin H
authors.initials: GH
authors.lastname: Thomas
authors.forename: Simon G
authors.initials: SG
authors.lastname: Ross
authors.forename: Tzung-Su
authors.initials: TS
authors.lastname: Ding
authors.forename: Pamela C
authors.initials: PC
authors.lastname: Rasmussen
authors.forename: Ali J
authors.initials: AJ
authors.lastname: Stattersfield
authors.forename: Peter M
authors.initials: PM
authors.lastname: Bennett
authors.forename: Tim M
authors.initials: TM
authors.lastname: Blackburn
authors.forename: Ian P F
authors.initials: IP
authors.lastname: Owens
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Gaston
mesh_terms: D000818:Animals; D044822:Biodiversity; D001717:Birds; D003247:Conservation of Natural Resources; D016208:Databases, Factual; D003710:Demography; D004777:Environment; D005843:Geography; D006801:Humans; D008962:Models, Theoretical; D011157:Population Dynamics