4.3. Conservation and management implications
Our study shows the negative impacts that alien species have on native
bird communities, and also show that the functional and taxonomic
diversity that alien species contribute does not compensate for that
caused by the loss of native species. Urban and agricultural landscapes
were more vulnerable to alien bird species invasion and, since we should
also rely on these disturbed areas for biodiversity conservation (Batáry
et al., 2020), future management strategies must prioritize habitat
restoration in these areas (e.g. increasing urban green spaces,
improving heterogeneity features in agricultural landscapes) to minimise
the chances of establishment of alien species, and to increase the
resistance of invaded communities. In our study region at least, this
should include the classification of the near-ubiquitous Feral Pigeon as
an alien species. Restoration strategies are well supported by the EU
“Nature Restoration Law” (i.e. European Green Deal) and should be
implemented along the impact assessment of alien birds on native bird
communities, through functional and phylogenetic perspective, instead of
focusing on a single alien species or diversity metric. Nonetheless,
future study following this direction, would need to include also the
three metrics of beta-diversity to have a better understanding of the
role of alien species on biodiversity and ecosystem functioning ofinvaded communities (Soares et al., 2022).