DOI: 10.6084/m9.figshare.23940456.v1
title: Data from: Non-native Red-billed Blue Magpie <i>Urocissa erythrorhyncha</i> expanded in lowlands with moderate forest cover, with no significant impact on native common bird occupancy, in Shikoku, southern Japan

description: We established an efficient method of surveys and analyses for understanding the distribution and impacts of the non-native Red-billed Blue Magpie (<i>Urocissa erythrorhyncha</i>) that has recently colonized forests in Shikoku, southern Japan. Specifically, we evaluated the effectiveness of playback surveys for enhancing the magpie detectability, and revealed drivers of the magpie distribution by the occupancy model that considers non-detected individuals in surveys and survey condition effects on them. Using this model, we mapped the potential distribution of suitable habitats across Shikoku. Furthermore, we also obtained the detection/non-detection data of native bird species [Narcissus Flycatcher (<i>Ficedula narcissina</i>), Varied Tit (<i>Poecile varius</i>), Japanese Tit (<i>Parus minor</i>), Japanese Bush Warbler (<i>Cettia diphone</i>)], and evaluated the impacts of the magpie on these native species occupancies using the multispecies occupancy model that considered interspecific interactions (i.e., co-occurrence or mutually exclusive occurrence patterns). Analysis codes under R and data for them are included in this dataset.NatFore: the proportion of natural forests to overall forests, calculated within 100 m as the detection radius for the magpieForest: forest cover (the proportion to lands) within multiple radii from sites (100 m, 200 m, 400 m, 600 m, 800 m, and 1000 m)Dem: the mean elevation within 100 m from each survey point, calculated using the elevational data that were provided by CGIS Japan and derived from the 10-m Digital Elevation Model (http://cgisj.jp/download_type_list.php)TPI: Topographic Position Index at a 250 m × 250 m scale, calculated by taking the difference between the elevation of the survey points and the mean elevation of the surroundings, and its negative value indicates a valley floor or concave, while a positive value indicates a ridge or convexdistance: the distance from the release pointSanjak: Detection (1) or Non-detection (0) of Red-billed Blue Magpie (4.3 means data from the third sampling in April)Date: survey season, the number of elapsed days (i.e., April 1 = 1)Time: survey time (Morning or Evening)Call: six types (A-F) of playback calls, included as categorical explanatory variables to express whether each call type is before (0) or after (1) playbackUguisu: Detection (1) or Non-detection (0) of Japanese Bush WarblerShijukara: Detection (1) or Non-detection (0) of Japanese TitYamagara: Detection (1) or Non-detection (0) of Varied TitKibitaki: Detection (1) or Non-detection (0) of Narcissus Flycatcherpred: predicted occupancy of Red-billed Blue Magpir across Shikokufarea: forest cover within a 600-m radius from the center of each cell (i.e., the average value of 11,289 cells) using the 10-m land-use mapdem: the mean elevation within the 100-m radius from the center of each cell (i.e., the average value of 317 cells) using 10-m DEM