Barbara Waringer

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Population density and habitat preferences of the Collared Flycatcher (Ficedula albicollis TEMMINCK, 1815) in floodplain forests – A case study from the Donau-Auen National Park, Lower Austria

The Collared Flycatcher (Ficedula albicollis, Temminck 1815, Muscicapidae) is one of a few insectivorous long-distance migrants with a slightly positive population trend. In spring 2015, the habitat preferences of a population in the floodplain forests of the Donau-Auen National Park, Lower Austria, were examined. Assuming that territories in good habitats will be occupied first, the following questions were addressed: In which order are territories established? What are the most important factors for a high quality habitat for Collared Flycatchers in the Donau-Auen? Is an early territory establishment related to a close distance to water bodies and a high insect density? Singing males were counted at randomly chosen points in six survey rounds. Additionally, possible breeding competitors and/or cavity providers, woodpecker holes, standing deadwood, flying insects, vegetation parameters (canopy surface roughness, forest type, forest age) and landscape variables (distance to water bodies and open land) were assessed. A model selection approach was used to identify the factors important for territory presence. 57% of the census points contained territories resulting in a population density of 7.28 territories/10 ha and 21.4 territories/10 ha estimated for a 50 m radius and a 25 m radius around the census points, respectively. The Distance Sampling method estimates densities of 8.68 to 13.72 singing males/10 ha. Canopy surface roughness proved being the best predictor for Collared Flycatcherterritories. Established territories were found with a higher likelihood at sites with higher canopy roughness. Further, territories with higher canopy roughness showed a tendency to earlier occupation. As forestry measures were stopped just recently (20 years ago) and canopy roughness is known to increase with stand age, the habitat quality of the remaining Danube floodplain forests east of Vienna for the Collared Flycatcher will most likely remain similar or will even further increase in the mid to long term.