The exponential model was fitted on the population census data from the RGPH (“recensement général de la population et de l’habitat”) done at the Firaisana level in 1993 combined with a more recent population census data done between 2004 and 2009 at the Fokontany level. On the left figure, the delimitation of the Firaisana (black lines) and Fokontanys (grey lines) covering our study areas (red lines) are represented on the map of Madagascar. On the right figure, the population evolution for each Firaisana is represented by two grey dots connected by a grey line. The mean exponential growth population model is represented by a plain black line. The mean population growth rate was estimated at 3.39%.yr−1 . The 95% confidence envelop including the Firaisana variability is represented with dashed black lines.