Most certainly the death of the birds was caused by electric shock. Two of the Imperial Eagles were found near the protected area "Kamenski Bair." One of them was an adult, the other - in the fourth immature plumage. The third bird, also in immature plumage, was found near one of the breeding pairs of Imperial eagles in the valley of the Tundza River. Two of the birds were found in September and November 2016, and the third - on February 23, 2017 by teams of Bulgarian Society for the Protection of Birds (BSPB) during a specialized study aimed to identify the riskiest power lines in areas which are critical for the Imperial eagle in Bulgaria.
The results of the studies and the satellite tracking of Imperial Eagles from Bulgaria showed that 80% of the young birds and a significant percentage of the adult birds are killed by electric shocks.
In order to protect the population of the globally threatened Imperial Eagle and reducing deaths caused by contact with the electricity network, "EVN Bulgaria Elektrorazpredelenie” in partnership with BSPB implement the project "Life for Safe Grid", funded by the LIFE Programme of the European Union.
So far, the project secured 476 hazardous electrical pillars of the Municipality of Sliven. Another 15 km overhead line with "bare" wires near Harmanli was replaced with PAS system with insulated wires. The biggest activity of the project includes the complete removal of aboveground power lines in some of the most important Imperial eagle areas in Natura 2000 zone "Sakar" and replacing them with underground cable. In 2016 in the Municipality of Topolovgrad were laid 43 km underground cable lines and removal of overhead power lines is pending. By this way we will achieve a full elimination of this kind of danger to birds.
Activities by securing the distribution network continued in 2017 with replacing 30 km conventional overhead lines in the Municipalities of Elhovo and Topolovgrad with completely insulated (PAS system), as well as installation of protective insulation pillars in Sliven.