Colonization speed is the ratio distance/time calculated site by site, from the initial releasing point (Site 1, Gandoulet), reference point. The horizontal axis of the graph indicates the number of years since the first releasing.

Before 1989, colonization speed varied from 73 to 3260 m/year, with a median value of 186 m/year (mean: 508.07m/year). From 1990 to 1999, colonization speed varied from 55 to 908 m/year, with a median value of 188 m/year (mean: 235.89m/year). From 2000 to 2009, colonization speed varied from 14 to 762 m/year, with a median value of 215.5 m/year (mean: 259.03m/year).

The analysis by step of 10 years showed that colonization speed have few evolved across time, with median speeds lower than 400 m/year. The only exception corresponds to site n° 39 (d'Ourseyre) for which, 3 years after beginning of introduction, the distance was 9780 m South-West of Gandoulet, corresponding to an outstanding speed of 3260 m/year!!

Flying over the points with the mouse let appear their coordinates (settlement year, speed in m/year).