The main aim of this paper is to analyze the effect of wind farms on population trends of breeding passerines assessing between years changes in abundance of the bird species under examination. The surveys were realized in a pilot area 4 years before and 4 after the wind farm construction, by means of the point count method. The collected data were then statistically analyzed using TRIM (TRends & Indices for Monitoring data) software, developed for the analysis of count data obtained from monitoring wildlife populations. Then, in order to evaluate whether the obtained population trends were influenced by the presence of the wind farm, they were compared with the national trends of the same passerine species during the same period. The results showed that during the wind farm construction phase some species had a decreasing trends but all of them increased their trends when the wind turbines were operating.