Post-fledging habitat selection of a Purple Heron Ardea purpurea revealed by GPS/GSM telemetry

The Purple Heron is a species of conservation concern in Europe, mainly threatened by the 23progressive degradation and reductionof wetlands. For future conservation practice, it is of pivotal 24importance to gather detailed knowledge of its habitat preferences. In June2018, a nestling of Purple Heron25from a sub-Alpine Lake in Northern Italy was equipped with a GPS/GSM device.Habitat selection during the 26post-fledging period (mid-July to mid-October) was analysed by superimposing the GPS locations to a fine-27grained field-based map, discerning 14 habitat classes as well as narrow(<2 m)and wide(>=2m)ditches.The 28contours of the home range were defined as the 99% kernel calculated on all the gathered locations, which 29were successively sub selected only retaining 2,017 locationsrepresenting the position of the bird every hour 30and all day long. Within the home range, the habitat availability was estimated by generating 10,000 random 31distributions of the locations.We firstly verified whether wide ditches were more frequently used by the 32heron if compared to narrow ones. Eventually, we calculated the ratio between the number of true and 33random locations falling into the different habitat classes, obtaining a series of class-specific selection ratios. 34We found a significant preference towards wide ditches compared to narrow ones. Freshly renewed 35reedbeds and cattail beds were strongly favoured, while high-bearing sedges and Black Alder were also 36significantly preferred but with lower indices. All the remaining habitats, including mature reedbeds, were 37significantly avoided. Our results reinforce the indicationthat the protection of minor landscape elements as 38ditches and small patches of wet habitats may be of pivotal importance to foster the long-term conservation 39of bird communities linked to the residual wetlands of the sub-Alpine belt.