The presence of an invasive bird, the Common Starling, in an urban landscape: habitat use and relationships with other bird species

The Common Starling (Sturnus vulgaris) is an invasive bird introduced in Argentina in the 1980's that shares flocks with both native and exotic birds. Analyzing interspecific relationships and habitat use of introduced species is crucial to understand the invasion process and to alert for negative impacts on biodiversity. We conducted bird counts from April 2015 to March 2016 in a town from east-central Argentina to assess relationships between starling abundance, bird community attributes, and a group of birds as potential competitors for food. We analyzed the relationship between lawn cover and starling abundance. The starling was strongly positively associated with total bird abundance, and negatively with total bird richness and diversity, whereas the abundance and richness of the group of potential competitors showed a weak negative association with starling abundance. We found positive relationships with the abundance of native birds (Rufous-bellied Thrush Turdus rufiventris, Shiny Cowbird Molothrus bonariensis, Bay-winged Cowbird Agelaioides badius and Eared Dove Zenaida auriculata), as well as negative relationships with (Monk Parakeet (Myiopsitta monachus) and Picui Ground-dove Columbina picui) and exotic birds (Rock Dove Columbia livia and House Sparrow Passer domesticus). Moreover, starlings were positively related to lawn cover. Negative associations with local species could be the result of either competition for resources or differences in habitat use, whereas positive associations could represent advantages related to food accessibility and reduction in predation risk, or similarities in habitat use in Argentina. Our results represent a first step to understand the ecology of this invasive species, as well as to identify native species under potential ecological threat.