A study led by Pau Lucio Puig, professor at the Gandia Campus of the Polytechnic University of Valencia, analyzes how the abandonment of agricultural land and its subsequent colonization by invasive plants are favoring the proliferation of the common waxbill (Estrilda astrild), a small exotic passerine bird of African origin that has spread throughout much of the Iberian Peninsula. The study, entitled Association patterns between farmland abandonment and the non-native Common Waxbill (Estrilda astrild) in the eastern Iberian Peninsula, has been published in open access in the Journal of Ornithology and can be consulted at the following link: https://link.springer.com/article/10.1007/s10336-025-02257-5

The introduction of exotic species is one of the main threats to biodiversity on a global scale, giving rise to significant ecological and economic impacts. In agricultural and peri-urban environments, landscape transformation, crop abandonment, and the presence of invasive vegetation create new ecological opportunities that some exotic species can exploit very effectively.

In this context, the study shows that the common waxbill has a remarkable ability to adapt to humanized landscapes, especially in abandoned agricultural fields, where it feeds opportunistically on both native and exotic seeds. The results reveal that the presence of the waxbill is positively associated with two of the most pernicious and widespread invasive plants globally, the pampas grass (Cortaderia selloana) and the giant reed (Arundo donax), which provide shelter and, in the case of pampas grass, also food through their seeds.

The Common Waxbill breeds continuously from May to approximately October, reaching its maximum densities in late autumn. The community-level study showed that when and where the common Waxtill was present, it dominated bird communities.

The study highlights how agricultural abandonment and subsequent colonization by invasive plants facilitate the expansion of exotic birds, potentially altering the functioning of Mediterranean ecosystems. The authors stress the need to strengthen long-term monitoring programs and implement landscape management measures aimed at curbing the expansion of invasive species and exploring the impacts they may have on native bird communities.

Photograph: Jesús Vilaplana