Density and composition of breeding bird communities in lowland forests

Bird communities were studied during three consecutive years (2020–2022) in forest fragments from the Western Upper Thracian lowland, Bulgaria. In total, 62 bird species with 4922 individuals were registered using point count methodology. Relative species abundance and frequency for all species was calculated. Density for the most abundant 19 species for the whole study area was estimated using DISTANCE software. Area-specific densities were estimated for nine species in nine of the studied forests. The results showed overall high species richness, which is consistent with other surveys in deciduous lowland forests. The most abundant species for the whole area made up to 61% of all registered species (Luscinia megarhynchos, Fringilla coelebs, Streptopelia turtur, Turdus merula, Oriolus oriolus, Sylvia atricapilla). The estimated densities were consistent with other studies in similar forest habitats. Species with the highest density was found to be Great tit D = 1.29 (1.14 – 1.46), followed by Hawfinch, European turtle dove, Common chaffinch, European robin and Blackbird, whereas specialist species (e.g. forest-interior) were less abundant. Eurasian hoopoe was found with lower densities for the whole territory D = 0.27 (0.23 – 0.31), while the Robin had the highest estimation for the forest of Begovo D = 2.28 (1.36 – 3.85).