The European serin is a species with a circum-Mediterranean distribution at a global scale (BirdLife International, 2024). In Europe it currently occupies the entire continent, as during the 19th century it expanded northwards and eastwards until it covered its whole range (Keller et al., 2020). In Spain it occupies the entire territory, including Ceuta, Melilla, and both archipelagos, but it is absent from alpine areas above the treeline and from treeless steppe habitats (Borràs and Senar in SEO/BirdLife, 2022).

The European serin occupies the whole Community of Madrid, including urban areas. It is absent from high mountain areas. It inhabits shrubland, irrigated crops, and gardens (Díaz et al., 1994).

In the national park it is found mainly in the southeastern half, in lower-altitude areas and suitable habitats on the foothills. In the central and northern parts of the park, where higher elevations and denser forests, meadows, and rocky areas predominate, its presence is more sporadic. It is common around La Pedriza, the Hoya de San Blas, and the foothill zones below the Sierra de los Porrones and La Maliciosa.