Like other major grassland ecoregions around the world, the Pampas in southeastern South America have suffered significant impacts over the last 400 years. Livestock grazing, agriculture, and, more recently, afforestation have led to substantial habitat alteration, resulting in negative impacts on grassland specialists. A primary example is the Pampas Meadowlark (Leistes defilippii), a globally threatened blackbird mainly restricted to large tracts of well-conserved native grasslands. While its former range covered most of the Pampas biome across eastern Argentina, Uruguay, and southern Brazil, it now survives in only a few localities within the first two countries. According to the latest data, only one to two thousand birds remain.

However, in the spring of 2016, for reasons not yet fully understood, the main nesting site was abandoned. Most concerningly, the birds could not be relocated elsewhere. In late 2016, a post-breeding flock was found, but bird numbers were significantly below historic records. In the following years, indirect evidence suggested a possible link between the disappearance of the birds and the use of a veterinary product that may have affected critical food resources, such as insect larvae. This potential connection has not yet been thoroughly investigated.

Surveys conducted over the past several years have documented a worrying decline, characterized by sparse records of a handful of individuals and abandoned nesting sites. However, a new conservation opportunity emerged in 2025 as approximately 35–45 pairs of meadowlarks reoccupied historic breeding grounds. Although these numbers are far from pre-2016 figures, these findings represent the most significant news for the breeding meadowlarks of the 'Campos de El Tapado' KBA in 10 years.