In many countries, the implementation of measures to protect declining species has led to the recolonization of some areas by bird species within their historic range. There is, however, a lack of quantitative tools for exploring and projecting such large-scale dynamics.
The Grey Heron (Ardea cinerea) is now a common species in France, however this has not always been the case. Indeed it was almost eradicated from France in the late nineteenth century by hunting and destruction. The species has been protected in France since 1975. After It’s protection after it was in 1975 that its staff has experienced impressive dynamic, enabling it to realize a recolonization of its former range repair.
We investigate this issue by an approach that makes use of both census and habitat suitability data and integrates them into a spatially explicit model of colonization dynamics (cellular automaton). Data analysis allowed us to quantify the positive effects of habitat quality on the probability of colonization, and to uncover both positive and negative density-dependent colony settlement processes. Projective simulations then allowed us to determine an inflection point in global colonization dynamics and predict a significant reduction in the colonization rate during the next 50 years. This makes it possible to project the spatial distribution of the species at different timescales, and to estimate the carrying capacity of France for the species (Lorrillière et al., 2010 ).