Photo 1. A boreal owl in an unusual type of habitat, the sub-Mediterranean forest at the foot of Mt Obruč (Photo by Nina Trinajstić)
A BOREAL OWL AT THE FOOT OF MT OBRUČ
In Croatia, birdwatchers are a “rare species” and bird sightings are few. That’s why any interesting sighting deserves to be mentioned. Such is the sighting of a boreal owl, which our colleague Nina documented with her camera on 11 February 2018 in the Zala region not far from Podkilavac at the foot of Mt Obruč. What makes this sighting so intriguing is the fact that the boreal owl is rarely found in our country because it is almost exclusively tied to Eurasian and North American boreal coniferous forests. Further south, it can find suitable habitats only in mountainous areas where coniferous forests grow, and in such places it can be considered a (post-) glacial relict.
Based on the sightings of owls of the boreal forest, such as the boreal owl, collected over the past decades by bird-watchers, researchers have been able to learn much about the interesting periodical fluctuations of small mammal populations (that are the prey of owls) in the northern regions of Eurasia and North America. One of the consequences of these fluctuations is the nomadic migration (> 100 km) of some owls of the boreal forest, in particular the boreal owl, from their usual boreal habitats towards the south, to the region of deciduous forests, for example. This migration takes place when the populations of small mammals are in decline, particularly in winter, when food is scarce as it is.
We will probably never know how, from where or why the boreal owl sighted came to the currently snow-covered Mt Obruč, but that does not make this sighting any less important. It is also interesting to note that a few years ago another boreal bird – the three-toed woodpecker – was also sighted on Mt Obruč. http://www.ju-priroda.hr/novosti.asp?id=novosti/62-troprsti-djetlic.html.