Data on the Study of Bird Distribution in Bulgaria in the Last 45 Years (1976-2020)

Unpublished data of field observations in many regions of Bulgaria in the last 45 years cover a total of 199 species (57 families, 18 orders), representing 47 % of recent country's bird fauna. They were registered in 1929 sites/species (many of them not existing at present, abandoned or destroyed) of 24 provinces (of total of 28), both in breeding and non-breeding season. Most of them are located far of popular bird-watching points, being less visited and remained beyond of common ornithological interest (border, high-mountain, or large agricultural or industrial regions). Among the observed birds, 82 species (40 %) are included in the Bulgarian Red Data Book. Three species are extinct, 13 – critically endangered, 26 – endangered, 36 – vulnerable, 3 – nearly threatened, and 1 – least concern.