The Global Distribution and Drivers of Alien Bird Species Richness

Abstract

Alien species are a major component of human-induced environmental change. Variation in the numbers of alien species found in different areas is likely to depend on a combination of anthropogenic and environmental factors, with anthropogenic factors affecting the number of species introduced to new locations, and when, and environmental factors influencing how many species are able to persist there. However, global spatial and temporal variation in the drivers of alien introduction and species richness remain poorly understood. Here, we analyse an extensive new database of alien birds to explore what determines the global distribution of alien species richness for an entire taxonomic class. We demonstrate that the locations of origin and introduction of alien birds, and their identities, were initially driven largely by European (mainly British) colonialism. However, recent introductions are a wider phenomenon, involving more species and countries, and driven in part by increasing economic activity. We find that, globally, alien bird species richness is currently highest at midlatitudes and is strongly determined by anthropogenic effects, most notably the number of species introduced (i.e., “colonisation pressure”). Nevertheless, environmental drivers are also important, with native and alien species richness being strongly and consistently positively associated. Our results demonstrate that colonisation pressure is key to understanding alien species richness, show that areas of high native species richness are not resistant to colonisation by alien species at the global scale, and emphasise the likely ongoing threats to global environments from introductions of species.

Insights from modeling studies on how climate change affects invasive alien species geography

“…As a result, most of the research on IAS and climate change is conducted on species that affect upper‐middle to high‐income countries. Yet, it is most likely that future hotspots of invasions might be located in newly industrialized and developing economies (see Dyer et al., 2017 for birds). Another potential bias comes from the lack of distinction between native and alien ranges where climate change effects can be divergent, as recently suggested for three invasive freshwater macrophytes that were predicted to increase in their alien range but decrease in their native range (Gillard, Thiebaut, Deleu, & Leroy, 2017).…”

The global avian invasions atlas, a database of alien bird distributions worldwide

“…This will enable future research to incorporate a measure of colonisation pressure ( sensu 14 ) into analyses, a variable that is an important determinant of alien species richness 15 but is usually unavailable.…”

Avian SDMs: current state, challenges, and opportunities

“…To investigate how and to what extent SDMs have been used in avian invasion biology, we carried out a literature search (see Supplementary material Appendix 1 and Table 1 for details on search procedures and the papers identified). Given the vast amount of data available on bird introductions (Blackburn et al 2009), it is surprising to see that our literature review uncovered only 27 papers applying SDMs to study avian invasions dealing with less than 10% of the 420 species that have established non-native populations worldwide (Dyer et al 2017). Moreover, studied species come from only 11 families, with Anatidae (15 species), Phasianidae (6), Estrildidae (5) and Psittacidae (4) being the most prevalent -the very taxa from which a higher than expected number of invasive bird species derive (Blackburn et al 2009).…”