Danube Delta is the second largest river delta in Europe, after Volga Delta, and the best preserved on the continent. Sacalin Island is a strictly protected area of the Danube Delta, declared biosphere reserve since 1938. The impact of human regarding the use of the same territories or interest in eating the same food resources disturbed bird’s habitats. The aim of this study was to investigate the distribution and ecology of passerine birds (Passeriformes) on the Sacalin Island in relation with anthropic changes. Data were obtained through the establishment of a permanent ringing station in Sacalin Island, with the support of the Romanian Ornithological Central and Nos Oiseaux Institute in Switzerland. As a working methodology, observations and bird ringing were made throughout the years 2007-2013, and distribution and ecology were analyzed. A total number of 6619 Passeriformes were collected, belonging of 13 familia. Among Passeriformes collected from Sacalin Island, Sylvidae familiae was the most divers with 14 species, followed by Muscicapidae with 8 species, Fingilidae (5 species), Turdidae (4 species), Paridae (3 species), Paradoxornithidae and Motacillidae (2 species) and Emberizidae, Oriolidae, Corvidae, Laniidae, Troglodytidae, and Hirundinidae with 1 species respectively. The predominant number of birds was found in Muscicapidae familiae (36.51%), followed by Sylviidae (29.65%), Turdidae (13.05%), Paridae (8.68% ), Laniidae (6.78%), Fringiliidae (2.07%), Troglodytidae (0.98%), Motacilidae (0.60%), Paradoxomithidae (0.51%), Oriolidae (0.50%), Emberizidae (0.40%), Corvidae (0.18%) and Hirundinidae (0.05%). In conclusion, our data suggest that the Sacalin Island is an area with a wide diversity of bird’s fauna, uncovering the ecology and distribution of birds could greatly improve the knowledge of bird’s dynamics and behavior.