Non-native spruce plantations represent a suitable habitat for Tengmalm’s Owl (Aegolius funereus) in the Czech Republic, Central Europe

Abstract

Anthropogenic activity can lead to deforestation and subsequent dramatic impacts on forest-dwelling animal species. In this study, we investigated the habitat use of a forest raptor (Tengmalm’s Owl Aegolius funereus) in an air-polluted area of the Ore Mountains (Czech Republic) that has been restored by non-native spruce. Based on a 14-year Tengmalm’s Owl nest-box breeding dataset, we found that the percentage of native Norway Spruce forest was higher for occupied nest boxes than for unoccupied ones within close surroundings of the nest (buffer radius of 25 m). Meanwhile, the percentage of non-native Blue Spruce (originally from Northern America) was higher for occupied nest boxes than for unoccupied ones within the home-range breeding area (buffer radius of 750 m). Moreover, the surroundings of non-predated nests (radius of 750 m) showed a higher percentage of Blue Spruce and a lower percentage of deciduous trees than surroundings of nests predated by Pine Martens. Although small mammal availability was not affected by habitat categories, we found a positive correlation between the percentage of Apodemus mice in the diet of owls and the percentages of both Blue Spruce and open forest area within the foraging area radius (750 m). We suggest that adult owls and young fledglings use remnants of tall, old-growth Norway Spruce forests as a safe refuge against avian predators, while secondary stands of non-native Blue Spruce are suitable for hunting both main prey types (Apodemus mice and Microtus voles), and also ensure good protection against nest predation by Pine Martens.