Niche expansion of the common waxbill (Estrilda astrild) in its non-native range in Brazil

Abstract

The geographical range of a species can change over time due to intrinsic or extrinsic factors, but the ecological niche of a species is hypothesized to be conservative and retained in time and space even during biological invasions. It has been documented that some species can experience niche shifts if natural barriers and other constraints are removed, allowing species to occur in areas with characteristics that are different from its native environment. This paper compares the realized ecological niches of the common waxbill (Estrilda astrild) in Africa (the native range) and Brazil (the non-native range) using reciprocal environmental niche modelling to determine if the species conserves its niche during the colonization of a new region. We found that the common waxbill has expanded its ecological niche in Brazil. This process has been facilitated by human interventions in the country’s natural ecosystems. Brazilian localities where the common waxbill is currently reported have higher temperatures, receive more rainfall, and exhibit denser vegetation coverage than the localities in the species’ native range. We suggest that a combination of intrinsic factors (behavior flexibility to explore and adapt to novel environments) and extrinsic factors (multiple introductions, road development and deforestation, Africanization of the tropical grasslands, and lack of competitors) acted together to facilitate the successful establishment of the common waxbill in the major Brazilian ecological regions and enable the expansion of the species’ ecological niche.