Authors: Marcolin, Fabio; Chamberlain, Daniel;Segurado, Pedro;Reino, Luís;

Alien bird species often negatively interact with native bird species leading to local biodiversity loss and trait homogenisation. Our aim was to assess bird communities resilience to alien bird species in highly human-modified landscape. We surveyed 190 randomly distributed points (stratified sampling: urban, agricultural and forest areas) using point counts around the Tagus Estuary area (Portugal). We ran Hierarchical Modelling of Species Communities models to infer bird co-occurences response to landscape composition, phylogeny and species traits. Urban and intensive agricultural areas showed lower species richness compared to forested and extensively managed agricultural areas. Urban and intensive agricultural areas were more suitable for alien bird species, whereas forest areas negatively affected alien bird species presence. We found that extensively managed agricultural areas negatively affected abundance of alien bird species, favouring ground feeding specialist species (e.g. Calandrella brachydactyla). Our results suggest that alien and generalist native species are favoured in anthropic disturbed areas, whereas forest and extensively managed agricultural areas favour native specialist species richness and abundance. Future management strategies should focus on enhancing habitat quality in more anthropized areas to promote avian diversity and improve resilience of bird communities to alien species.