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The paradox of invasion in birds: competitive superiority or ecological opportunism?

Overview of attention for article published in Oecologia, December 2011
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The paradox of invasion in birds: competitive superiority or ecological opportunism?
Published in
Oecologia, December 2011
DOI 10.1007/s00442-011-2203-x
Pubmed ID

Daniel Sol, Ignasi Bartomeus, Andrea S. Griffin


Why can alien species succeed in environments to which they have had no opportunity to adapt and even become more abundant than many native species? Ecological theory suggests two main possible answers for this paradox: competitive superiority of exotic species over native species and opportunistic use of ecological opportunities derived from human activities. We tested these hypotheses in birds combining field observations and experiments along gradients of urbanization in New South Wales (Australia). Five exotic species attained densities in the study area comparable to those of the most abundant native species, and hence provided a case for the invasion paradox. The success of these alien birds was not primarily associated with a competitive superiority over native species: the most successful invaders were smaller and less aggressive than their main native competitors, and were generally excluded from artificially created food patches where competition was high. More importantly, exotic birds were primarily restricted to urban environments, where the diversity and abundance of native species were low. This finding agrees with previous studies and indicates that exotic and native species rarely interact in nature. Observations and experiments in the field revealed that the few native species that exploit the most urbanized environments tended to be opportunistic foragers, adaptations that should facilitate survival in places where disturbances by humans are frequent and natural vegetation has been replaced by man-made structures. Successful invaders also shared these features, suggesting that their success is not a paradox but can be explained by their capacity to exploit ecological opportunities that most native species rarely use.

Mendeley readers

The data shown below were compiled from readership statistics for 214 Mendeley readers of this research output. Click here to see the associated Mendeley record.

Geographical breakdown

Country Count As %
United States 5 2%
Spain 3 1%
Austria 2 <1%
Italy 1 <1%
France 1 <1%
Switzerland 1 <1%
Brazil 1 <1%
South Africa 1 <1%
New Zealand 1 <1%
Other 5 2%
Unknown 193 90%

Demographic breakdown

Readers by professional status Count As %
Student > Ph. D. Student 52 24%
Student > Master 42 20%
Researcher 41 19%
Student > Bachelor 20 9%
Other 13 6%
Other 31 14%
Unknown 15 7%
Readers by discipline Count As %
Agricultural and Biological Sciences 124 58%
Environmental Science 46 21%
Psychology 4 2%
Arts and Humanities 4 2%
Unspecified 2 <1%
Other 8 4%
Unknown 26 12%