Classification of Grus monacha’s wintering habitats based on their number and activity time

Chongming Dongtan is an important stopover point and wintering habitat for the nationally protected water bird Grus monacha. Due to the influence of intensive human activities and exotic species Spartina alterniflora, the suitable wintering habitats have changed substantially, which brings serious challenge to the protection of G. monacha and many other species. Four variables were used to analyze the habitat for the G. monacha: cover type, vegetation coverage, tidal flooding depth and distance from the levee. We investigated the influence of the above environmental variables on the activities of G. monacha, and used the number and activity time of crane population as a parameter to quantify the suitability of these variables. We calculated the suitability index of G. monacha’ s habitat in Chongming Dongtan, and mapped the spatial distribution of the index values. The results indicated that the suitable, moderately suitable, marginally suitable and unsuitable wintering habitat areas were 697, 469, 282, and 352 hm², respectively. The suitable and unsuitable habitats occupied 38.7% and 19.6% of the total area, respectively. Moderately and marginally suitable habitats covered more than 40% of the total area, which can be improved to become suitable for G. monacha potentially. We provided some suggestions about how to protect the G. moncha population and enlarge the suitable habitat area such as providing food in the moderately and marginally suitable habitats to enlarge the suitable wintering habitat, and take measures to recover the native species Scirpus mariqueter.