The ongoing processes of urbanization, illegal construction, uncontrolled and unplanned loggings are hampering the habitats of rare and delicate animal species. One of these rare species are boreal owls, living in a forest mountainous ecosystem of Vareš area. Due to overexploitation of forests, a large portion of forests are becoming coppice forests, which results in owls having no place to make their nests. Without mature trees, there are no hollows in trees, so owls have to nest in alternative locations, becoming more vulnerable to predators and negative weather conditions. Additionally, ornithofauna in Vareš area is understudied, so CENER 21 came up with a project Research on boreal and forest owls in Vareš area, including active measures of protection.

The main goal of the project was to investigate endangered and vulnerable species of boreal and forest owls in the Vareš area as well as to implement active protection measures to increase the number of young owl individuals. The focus of the research were three boreal owl species which includes:

  • Eurasian Pygmy-Owl (Glaucidium passerinum);
  • Boreal owl (Aegolius funereus);
  • Ural owl (Strix uralensis), but also the
  • Tawny owl (Strix aluco).

These owl species are classified as endangered or vulnerable species in the Red List of Fauna of the Federation of Bosnia and Herzegovina, and are on the list of Annex I of the European Union Birds Directive. Up to date, there was no systematic research done on boreal and forest owls in BiH, although they are endangered and represent a significant sustainability factor for agriculture and forestry, regulating the number of rodents – well known infectious disease vectors.

The project included three phases:

  • Phase 1 – the research of owl species at 90 locations at the wider area of Crepulje hill, Vranjkovci, Pogari as well as area of Zvijezda mountain, from the tunnel Ponikva to village Oćevija on the east and Zubeta village on south (spring and autumn, 2019)
  • Phase 2 – implementing of active protection measures – placement of 36 owl nesting houses in the areas where boreal owls were detected in the previous phase (autumn, 2019)
  • Phase 3 – monitoring the occupancy of owl houses (spring, 2020)
Distribution of owls/Project archive

A total of 35 territories of boreal and forest owl species were mapped during the phase 1, out of which 15 territories of small owl, 14 territories of boreal owl and 6 territories of long-tailed owl, while forest owl was not mapped in the study area at all. During the second phase, 21 nesting houses were placed for boreal owls, 10 for long-tailed owl and 5 for forest owl, which makes a total of 36 owl nesting houses at three study areas: Semizova Ponikva – Vranjkovci; mountain Zvijezda and upper stream of river Tribija. Monitoring results of the owl houses occupancy indicated that houses were uninhabited during spring 2020.

Locations where owls have been recorded/Project archive

To conclude, this research has shown that Zvijezda mountain and wider area of Semizova Ponikva – Vranjkovci location are characterized by a good population of boreal owl species: Eurasian pygmy owl (Glaucidium passerinum – small owl); Boreal owl (Aegolius funereus); Ural owl (Strix uralensis – long-tailed owl). By implementing active protection measures, the first study area for owl monitoring in Federation of BiH has been established. The area represents a pre-condition to gather data on behavior, nesting and reproduction of boreal owl species as well as significant method for active protection of owls, by increasing the nesting owl couples. Owl nesting houses placed in the area of Semizova Ponikva – Vranjkovci, mountain Zvijezda and upper stream of Tribija river, represent the first and only study area for active protection and long-term monitoring of owl population in Bosnia and Herzegovina.

Throughout 10 year-period, this area shall provide valuable data on density and population state, nest size, nesting success rate, morphometric characteristics of local owl species as well as bird migrations marked with bird rings by recently established bh. Centre for bird marking. Moreover, monitoring results indicate the complexity of owl species and their complexed behavior principles. Although supreme predators, owls are extremely sensitive to various factors, including the most important: disturbing, destroying of the habitat, unstable weather conditions as well as lack of food, which could cause complete or partial absence of owl nesting. The lack of food is the most probable reason for owls not inhabiting nesting houses placed within this research.

In the next 10 to 15 years, activities on research and protection of owls will continue, depending on the resiliency of nesting houses. Besides, additional mountain areas are planned to be included – where similar study areas would be established, enabling higher quality of results.

This research represents a pioneering project of active protection of endangered bird species in BiH and represents a model for the implementation of active protection programs for other species as well. CENER 21 team is proud to be the pioneer of this kind of research and hopes are that the results will be helpful for decision makers in the area of forestry and nature protection.

The project is funded by the Environmental Protection Fund of the FBiH, through the Public Call for environmental non-profit organizations in Federation of BiH.