High predictability in introduction outcomes and the geographical range size of introduced Australian birds: a role for climate

Abstract

Summary 1.We investigated factors hypothesized to influence introduction success and subsequent geographical range size in 52 species of bird that have been introduced to mainland Australia. 2. The 19 successful species had been introduced more times, at more sites and in greater overall numbers. Relative to failed species, successfully introduced species also had a greater area of climatically suitable habitat available in Australia, a larger overseas range size and were more likely to have been introduced successfully outside Australia. After controlling for phylogeny these relationships held, except that with overseas range size and, in addition, larger-bodied species had a higher probability of introduction success. There was also a marked taxonomic bias: gamebirds had a much lower probability of success than other species. A model including five of these variables explained perfectly the patterns in introduction success across-species. 3. Of the successful species, those with larger geographical ranges in Australia had a greater area of climatically suitable habitat, traits associated with a faster population growth rate (small body size, short incubation period and more broods per season) and a larger overseas range size. The relationships between range size in Australia, the extent of climatically suitable habitat and overseas range size held after controlling for phylogeny. 4. We discuss the probable causes underlying these relationships and why, in retrospect, the outcome of bird introductions to Australia are highly predictable.

What determines the impact of alien birds and mammals in Europe?

“…Establishment is more likely for, amongst other things, populations of generalist and behaviourally flexible species released in larger numbers (Cassey et al 2004b;Forsyth et al 2004;Sol et al 2005bSol et al , 2008Jeschke and Strayer 2006;Blackburn et al 2009a, b). What determines the extent of spread following establishment is poorly understood, although data for alien birds in New Zealand and alien mammals in Australia show that species with higher population growth rates and released in larger numbers end up with wider distributions (Duncan et al 1999;Forsyth et al 2004; but see Duncan et al 2001). We can now add to this catalogue the traits relevant for the magnitude of alien bird and mammal impacts.…”

Strong human association with plant invasion success for Trifolium introductions to New Zealand

“…Species with larger native ranges may have achieved greater intentional and unintentional propagule pressure (43), facilitating rapid spread. Alternatively or additionally, such species may have spread quickly because of ecological versatility (41,42) or preadaptation to the New Zealand climate (15,48). Finally, species with longer flowering periods, particularly in New Zealand, tended to spread more rapidly (Table S10); this attribute is often associated with invasion success (49), via mechanisms such as associated longer fruiting period and increased seed transport probability.…”

“…The number of biomes in which a species occurred (diversity of conditions tolerated) was determined by overlaying the native range onto a World Wildlife Fund biome map (71). A climate match index was calculated as the number of 10Ј ϫ 10Ј latitude-longitude grid cells in New Zealand that had a 95% or better match to the climate of any 10Ј ϫ 10Ј grid cell in the species' native range (15). Climate match was calculated by using the Euclidean distance-based CLIMATE algorithm (72) and a global meteorological dataset (73).…”

“…This stage-based approach has improved our understanding of animal invasions (15)(16)(17)(18), but its application to plants has been hindered by a lack of comprehensive data on which species have succeeded or failed at each stage.…”

Australasian bird invasions: accidents of history?

“…The most consistent and powerful predictor of invasion success for birds in Australasia has been shown repeatedly to be introduction effort by humans-both in terms of the number of individual birds released (often termed 'propagule pressure'), and the number of separate attempts at release (see Newsome & Noble 1986;Veltman et al 1996;Duncan 1997;Green 1997;Duncan et al 1999;Blackburn & Duncan 2001a;Duncan et al 2001;Duncan et al 2003). Similarly strong relationships have been found when examining large mammal and insect invasions (see Daehler & Strong 1993; and references cited therein).…”