Following alien birds along the pathway to impact
Tim Blackburn
Department of Genetics, Evolution & Environment, Centre for Biodiversity &
Environment Research, London, UK
t.blackburn@ucl.ac.uk
Biological invasions by alien species represent one of the primary ways in
which human activities are changing global biodiversity. Alien invaders can
have substantial effects on the ecosystems into which they have been
introduced, and on human economic and social enterprises in those same areas.
Yet, not all species become invaders, and not all invaders have deleterious
impacts, suggesting that there must be variation in factors that determine
success or failure.
My talk will be divided into two parts. In the first, I will discuss how
evidence from one particular taxonomic group, birds, helps us to understand
what drives the invasion process by alien species. I focus on birds because old
and new data are giving us new insights into the patterns and processes
underlying invasions by species in this taxon. I will describe how new data are
revising our view of the magnitude and extent of alien bird invasions, helping
to trace the history of introductions, and identifying the drivers of alien species
establishment and spread.
In the second part, I will consider variation in alien species impacts, and
in particular present a new method we have developed to help evaluate and
compare (and hopefully eventually to predict) the magnitudes of environmental
impacts of different alien species. The method can integrate impacts that
concern different levels of ecological complexity (from effects on individual
behavior to ecosystem dynamics), measured on a wide range of metrics, across
many different spatial and temporal scales. Our hope is that the method will
help with efforts to determine and prioritize appropriate management actions
for alien taxa with environmental impacts, and can also be extended to provide
a similar tool for taxa with socio-economic impacts.