Some signs suggesting the presence of an eagle-owl in nature
The Eurasian eagle-owl (Bubo bubo) is Europe’s largest owl. It can be found fairly often in the County of Primorje and Gorski Kotar, particularly in the Littoral and on the Kvarner islands. The habitats it chooses are rocky ravines or ridges that provide a sufficient number of secluded stone ledges, cavities or holes where it can build a nest and roost during the day.
The eagle-owl is difficult to detect when perched on a cliff because the colour of its feathers blends perfectly into its environment. But the primary reason we rarely have the chance to spot one in its habitat is because of its predominantly “night-life” style. However, the presence of an eagle-owl can be established even without a direct sighting, in most cases by hearing its call or by finding signs that suggest one is living in the area.
Typically, birds of prey seek out trees in positions dominating over the surrounding area. Owls are especially fond of cliffs that afford an unhindered view of their territory and serve as an observation post, a place from which it hoots or a place to bring prey. Such spots are characterised by the presence of eagle-owl droppings, feathers or pellets, or by the remains of their prey.
Interestingly, nitrophilic lichens of the genus Caloplaca and Xanthoria appear in spots (for example, a ledge in a cliff) where eagle-owl droppings have accumulated over the years or generations. So the presence of these lichens may also be a clue that eagle-owls once nested in a certain area from which they disappeared over time.