Mudanças no uso e na cobertura do solo impulsionam a expansão geográfica da ave migratória Sporophila lineola na América do Sul

Abstract

The homogenization of habitats and landscape changes for anthropic land use are some of the main threats to global biodiversity. These changes can directly alter landscape characteristics, influencing the occurrence and permanence of species in a given location. Several species of birds associated with agricultural land in Europe, the so-called “farmland birds”, are experiencing severe population declines since the 1970s, mainly due to habitat loss driven by the intensification of agriculture. However, contrary to what has been documented for these birds in temperate regions, many birds associated with agricultural areas in South America, which are analogous to European farmland birds, have expanded their ranges in recent decades. The reconstruction of the expansion history of these birds can reveal important ecological aspects for understanding the dynamics of shrinkage and expansion of bird populations associated with these environments. Given the above, we investigated the temporal dynamics of the geographic distribution of a tropical migratory bird associated with anthropic environments: Sporophila lineola. We aim to investigate the hypotheses that: i) S. lineola expanded its geographic distribution to southeastern and southern regions of Brazil during the last 100 years and ii) this expansion was driven by changes in land use and land cover, with the species preferring anthropic habitats. We used data from the literature, museum specimens and citizen science to unravel the species range area. In addition, we used historical maps to access land cover and land use changes. Our findings confirm the hypothesis that S. lineola expanded its geographic distribution to southeastern and southern Brazil in the last 100 years. Towards the southeast, its expansion started in the 1940s, and its expansion to south in the 1990s. Our results also support the hypothesis that the expansion of S. lineola is related to changes in land use and land cover, being the species generally found in anthropic areas and not in natural areas, whether forests or savannas. The documentation of this process allows us to relate the alteration of habitats with their successful occupation by opportunistic species and provides us with an alert about how anthropic alterations in the landscape can play a decisive role in the dynamics of species occupation. While some species benefit from such changes, others are harmed, which can be influenced not only by the degree of human interference in the landscape, but also by the time of occurrence of these changes. The European experience with farmland birds has a lot to teach us about how the history of landscape changes can influence the conservation status of a species, launching a reflection on how well-established populations of little conservation concern can become vulnerable in the future. It is not the purpose of this study to determine what will be the conservation status of S. lineola and other South American farmland birds in the future, but just to debate it. Given the dramatic global changes underway, this study proves to be a provocative invitation to reflect on how these changes will influence South American farmland birds.