Wildlife triangle

Wildlife triangle data, winter census Species-specific annual snow-track counts and average snow-track abundance indices in 50 × 50 km grid cells. The snow-track abundance index for a wildlife triangle (a ~12 km line transect) is calculated as N / (km_counted × snow_days). Here N is the number of snow-tracks crossing the transect line. The denominator stands for counting effort, consisting of the kilometers counted (km_counted) multiplied with the number of days during which tracks have accumulated (snow_days). The snow days are counted from last snowfall, or from the timing of a pre-mapping of snow-tracks, which prevents from recounting the tracks during the actual survey. The presented index for a given species, year and grid cell is calculated as the arithmetic mean index over all triangles, whose point of gravity are within the focal grid cell. In addition to the species-specific average abundance indices, also the number of snow tracks recorded, and the number of triangles counted are reported. The grid is constructed according to the ETRS-TM35FIN -coordinate system and the grid cell locations are given using the lower left corner coordinates (“lon” and “lat”).