**4. Discussion**

Based on the occurrences as rare winter vagrants in the neighboring Balkan countries, [7] (1990) list two additional species as probable for the Bulgarian avifauna—*S. ulula* (subspecies *S. u. ulula* Linnaeus, 1758.) and *B. scandiacus*. In the last more than three decades, there have been no sightings of both species, but we do not rule out the possibility of their records. Both species have a propensity for non-periodic long winter migrations to the south.

*Owls (Strigiformes Wagler, 1830) in Bulgaria: Past and Present (A Review of the Fossil Record… DOI: http://dx.doi.org/10.5772/intechopen.107371*

#### **Figure 4.**

*A shot Eagle owl (Bubo bubo bubo). Near Town of Belogradchik (Vidin Region, NW Bulgaria). 01.10.1993. Photograph: Zlatozar Boev.*

*B. scandiacus* is already established in the country, albeit in the Late Pleistocene, and for *S. ulula*, its Late Pleistocene presence has recently been established in the Eastern Palearctic as far south as even North Vietnam [46].

Although all owls in Bulgaria are protected by law, numerous are the hazards that still cause their death. The road kills from traffic have the most significant impact. In the open plain and lowland landscapes of Southern Bulgaria, Barn owls especially often die like this. However, they are not the only victim of the roads among the owls. Some species preferring woodlands and forest habitats also die in the same way on mountain roads (**Figure 5**).

At night, owls easily find the still warm bodies of killed or injured birds and small mammals on the roadway and swoop down on easy prey. In such situations on the road, blinded by the powerful headlights of cars, they are run over. Barn owls often die like this every year in southern Bulgaria.

#### **Figure 5.**

*A Tawny owl (Strix aluco aluco) run over on the road. Studenets Natura 2000 Special Protected Area (NC Bulgaria. Photograph: 12.11.2009. Zlatozar Boev.*

#### **Figure 6.**

*A Little owl (Athene noctua indigena) died from the 230-volt electric voltage on open power lines in the village of Archar (Vidin Region, NW Bulgaria). Photograph: 12.11.2009. Zlatozar Boev.*

A special survey of a 68-kilometer section of the Thrace highway between the cities of Pazardzhik and Plovdiv found that seven individuals of *A. otus* and five individuals of *T. alba* died in 20 days [47].

Some other relatively rare factors also contribute to owl mortality. In the urban areas (even rural), owls are sometimes injured and being killed by the electricity power as a result of flying into overhead wires (**Figure 6**). Unfortunately, not only small owls such as Little owls, but also the largest Eagle owls die from an electric shock from a short circuit. Such a case is presented by [48], making a proposal to replace electric poles or secure them with respect to birds. More than 30 years have passed since then, but today the situation is not much different.
